The Empirical Untenability of Sentient Artificial

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Honors Theses
5-22-2011
The Empirical Untenability of Sentient Artificial
Intelligence
Andrew Joseph Barron
Dickinson College
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"If you gotta ask, you ain't never gonna know"
THE EMPIRICAL UNTENABILITY
OF SENTIENT ARTIFICIAL INTELLIGENCE
By:
Andrew Barron
Submitted in partial fulfillment of Honors Requirements
for the Department of Philosophy
Professor Jessica Wahman, Supervisor
Professor Crispin Sartwell, Reader
Professor Susan Feldman, Reader
Professor Chauncey Maher, Reader
May 22, 2011
"All sentience is mere appearance - even sentience capable of passing the Turing test."
Tuvok
Star Trek: Voyager
"The key distinction
here is between duplication and simulation.
ever constitutes duplication."
John Searle
tvunds, Brains, and Science
And no simulation by itself
TABLE OF CONTENTS
INTRODUCTION
1
CHAPTER ONE: MINDS AND/OR COMPUTERS
WHAT IS COMPUTATION?
4
IS A MIND A COMPUTER?
9
IS A COMPUTER A MIND?
13
CHAPTER TWO: THE ENIGMA OF FAMILIARITY
THE HARD PROBLEM
23
ARGUMENTS
28
FROM INEFFABILITY
CHAPTER THREE: DO ANDROIDS DREAM OF ELECTRIC SHEEP? WE'LL NEVER KNOW FOR SURE
THE EXPLANATORY GAP
39
MCGINN'S THEORY OF COGNITIVE CLOSURE
43
CRITICISM AND RESPONSE
52
Al, CONSCIOUSNESS, AND BLADE RUNNER: TYING EVERYTHING TOGETHER
56
CONCLUSION
62
WORKS CITED
63
INTRODUCTION
The ultimate goal of Artificial Intelligence
ascribe it to a computer.1
{Al) is to model the human mind and
Since the 1950s, astounding progress has been made in the field,
leading some to defend "strong Al," John Searle's term for the theory that it is possible
to
write a computer program equivalent to a mind. As a result, a common trope in science
fiction from Isaac Asimov to James Cameron is the idea of sapient and sentient robots living
amongst humans, sometimes peacefully, but more commonly not. In Ridley Scott's Blade
Runner, androids indistinguishably
humanlike in appearance and behavior live as outlaws
among human beings, hiding in plain sight.
entertainment,
The idea of the strong Al makes for good
but is it actually possible? Is it within the realm of human capability to
synthesize consciousness?
To many scholars and researchers, the answer is a resounding
science, the interdisciplinary
amalgamation
"yes!"
of neuroscience, computer science, philosophy,
linguistics, and psychology, has churned out increasingly advanced instances
than half a century.
Cognitive
of Al for more
This paper is an attempt to restrain the mounting excitement.
There is
no doubt that Al is an incredible idea with far reaching implications already in effect today.
The marketplace is already saturated with "smart" cars, calculators, wristwatches,
and
dishwashers, but the average consumer generally avoids thinking about what that really
means. Does the luxury car that parallel parks itself know that it is parallel parking?
1
'Mind' is a controversial
term.
Intelligence does not presuppose mentality,
1
Simply
as we shall
because a device is touted by advertisers as "intelligent" does not entail the existence of a
conscious mind.
The purpose of my argument is not to prove the impossibility
computer,
of a conscious
but to prove the empirical untenability of ever knowing whether or not we have
succeeded in producing one. Consciousness is not something we can detect by observing
behavior-including
brain behavior - alone; just because something seems sentient does
not necessarily mean that it is. There is an explanatory gap between brain behavior and the
phenomenon
of conscious experience that cannot be solved using any extant philosophical
or scientific paradigms.
Hypothetically,
if we were to ever fully grasp the nature of what
consciousness is and how it arises and express it in the form of a coherent theory, it might
be possible to ascribe such a theory to an artifact.
transcend the explanatory gap and definitively
My thesis is a three-pronged
Even so, no conceivable test can
prove the existence of a sentient mind.
argument against the possibility of ever knowing for
sure whether or not we succeed in building a self-aware, sentient, conscious computer.
first tier is an explanatory discussion of computation
and the Turing test. Here I address
various arguments for computer minds and the theoretical
artificial intelligence.
continuously
experiment
The
I also discuss the counterarguments
underpinnings for Strong
that cognitive science
fails to rebut. I place special emphasis on Searle's Chinese Room thought
and its implications for the possibility of machine sentience. The second tier is a
discussion of what it means to be a conscious agent. I reject reductionism
in any form as
acceptable solutions to the mind-body problem because of the explanatory gap fatally
separating first-person
introspective
accounts of consciousness and third-person observable
2
neuro-behavioral
correlates.
In the final section
I support Colin McGinn's cognitive closure
hypothesis by defending his view that the mind-body problem is inherently
because a full understanding
of consciousness
Blade Runner and its antecedent
the impossibility
is beyond our epistemic
insoluble
limits.
Using the film
novel Do Androids Dream of Electric Sheep?, I aim to prove
of ever differentiating between a conscious,
"strong" Al and one that
behaves as if it were conscious, but has no inner life whatsoever,
3
also known as "weak" Al.
CHAPTER ONE
MINDS AND/OR COMPUTERS
WHAT IS COMPUTATION?
Throughout
definitions
the course of my research, I have encountered
of the word 'computer'.
a bevy of disparate
The Oxford Dictionary of Philosophy defines it as "any
device capable of carrying out a sequence of operations in a defined manner" (Blackburn
2008). Computers permeate every aspect of modern society, from the microchips in
hearing aids to massive parallel-processing
supercomputer
supercomputers.
Recently, IBM built one such
called Watson that competed on Jeopardy! against the two most successful
contestants in the show's history.
Watson seemed to have no problem comprehending
the
complex linguistic puzzles posed by Trebek, answering them in record time. As impressive
IBM's creation may be, does it function at all like a human brain? Are these electronic
operations equivalent to whatever phenomena are responsible for human thought?
Numerous cognitive scientists, philosophers, computer scientists, and neuroscientists
say yes (Carter 2007). Computationalism
the functional
representation
would
is a cognitive theory that posits that the mind is
of the external world through the manipulation
symbols; the mind is software within brain hardware.
4
of digital
Before I discuss
computationalism
look at what a computer is. John Haugeland
automatic formal system" (Haugeland
in greater detail, it is important
defines a computer as "an interpreted
1989, 48). To understand
first decipher what each of its component terms signifies.
tokens to be manipulated
Take chess, for instance.
to take a closer
this definition, we must
A formal system is comprised
according to a set of predetermined
of
rules, not unlike a game.
Before the game starts and regardless of who is playing, it is
decided that a pawn can only move one (or two) spaces forward, and one space diagonally
when attacking.
Unless different rules are decided on before the game starts, these rules
are set in stone.
Instead of physical pieces, computer tokens are electronic
and invisible to
the eye.
Formal systems like chess and checkers are necessarily digital. 'Digital'
means
discrete and precise while its opposite, 'analogue' means variable or nebulous.
The
alphabet is digital - A, B, C, D ... are static and discrete with no middle ground between A
and B. The station preset buttons on car radios are digital, while an "old fashioned"
analogue.
frequency.
dial is
If button '1' is set to 98.5 MHz, pushing the button will reliably set that exact
But when the driver of a 1983 Ford Bronco turns the tuner knob, it is effectively
impossible to tune the exact same frequency every time.
To my knowledge, all existing
digital computers are binary, using strings of ls and Os as tokens.
Formal systems are completely self-contained,
meaning that the rules only apply to
tokens within the system itself; 'black knight' seldom means 'movement
restricted
to two
spaces by one space' outside a the realm of a chess match. As a result, the "outside world"
is irrelevant.
Chess can be played indoors, outdoors, on the moon, or underwater
5
with
pieces made from plastic, gold, or elephant meat; the medium is irrelevant.
All that
matters is that the symbols pertain to the same system of rules, or syntax.
As we shall see
later, the idea of medium independence is extremely relevant to the field of artificial
intelligence.2
So far we have learned that computers are digital, self-contained,
and are syntactic.
A formal system is automatic if it works or runs devoid of any external influence.
In his
discussion of automatic systems, Haugeland imagines a fanciful example: "a set of chess
pieces that hop around the board, abiding by the rules, all by themselves"
pencil that writes out formally correct mathematical
any mathematicians"
or "a magical
derivations without the guidance of
(Haugeland 1989, 76). A computer becomes automated when its legal
moves are predetermined
and carried through algorithmically.
An algorithm
works like a
flowchart, a "step-by step recipe for obtaining a prespecified result" (Haugeland
1989, 65).
Algorithms are designed to work indefinitely in finite time. For example, a programmer can
design a procedure that alphabetizes a set of data. The algorithm used for this program can
be used reliably with new sets of data ad infinitum.
In the 1930s, computer pioneer Alan Turing theorized that a device could be built
that manipulates symbols written on spools of tape into different states according to an
algorithm.
The Turing machine was not designed to be practical but to lay out the
theoretical
framework behind computation,
"a mathematically
(Penrose 1994, 65). Turing and mathematician
idealized computer"
Alonzo Church realized that, in principle, any
algorithm could be iterated on a properly programmed Turing machine.
2
This concept will arise again in my later discussion of functionalism
realizability.
6
Turing later
and multiple
conceived of the Universal Turing machine (hereafter referred to as UTM), which can
simulate any arbitrary Turing machine. He wrote:
The special property of digital computers, that they can mimic any discrete
state machine, is described by saying that they are universal machines.
The
existence of machines with this property has the important consequence
that, considerations of speed apart, it is unnecessary to design various new
machines to do various computing processes. They can all be done with one
digital computer, suitably programmed for each case. It will be seen that as a
consequence of this all digital computers are in a sense equivalent. [Turing,
quoted in Dreyfus 1994, 72]
A UTM "can implement any algorithm whatever," which means that any modern computer
is a UTM (Searle 2008, 88). The laptop in front of me is designed to implement
software,
cohesive sets of algorithms written by programmers. It can implement any software
plugged into it.3
As we all know, UTMs are greatly useful and extremely versatile.
Deep Blue, a chess playing supercomputer,
In 1997, IBM's
competed against world champion Garry
Kasparov. In a thrilling upset, the advanced programming
machine defeated Kasparov,
showing the world how far computer intelligence had come. The two competitors played
very different chess, however. Deep Blue used brute force processing - multiple computers
running in parallel in order to power through the 1050 possible moves on the chessboard.
Kasparov is a human, and as Hubert Dreyfus explained to me in a personal
correspondence
"[A chess program] needs to look at millions and millions of connections per second to do
something that human beings do in an obviously entirely
different
way, that's true of the
chess thing already[ ... ] Grandmasters look at two or three hundred at most" (Dreyfus
3
My MacBook Pro cannot run any program (i.e .. exe files), but it can surely implement any
program in that it can be inputted and cause some sort of output.
7
2011).
Granted, a grandmaster's chess abilities far surpass the average human,
extremely unlikely that he "computes" such an astronomical
but it is
number of possibilities every
turn.
Is Kasparov's mind nothing more than a slow computer?
Many theorists believe
this
to be so, as we shall soon see. But a crucial barrier separating Kasparov's mind from a UTM
is consciousness, the poorly understood phenomenon that makes us sentient and sapient.
Humans are conscious, no doubt, but there is no definitive proof that computers can or will
ever achieve sentience. For starters, Kasparov has perceptual faculties: sight, touch, taste,
etc., while Deep Blue does not (the mainframes weren't even in the room). However,
apparatuses like electronic eyes, acoustic receivers, and pressure-sensitive tactile devices
have existed for years. Hypothetically, the series of parallel processing computers
comprising Deep Blue could be significantly shrunk and placed inside a humanoid robot,
along with high-tech perceptual devices (call it DB2). It seems that the only thing separating
Kasparov and DB2 is the latter's one-track mind, so to speak; its only function is playing
chess. On the other hand, as Steven Hamad argues in Minds and Machines, "It is unlikely
that our chess-playing capacity constitutes an autonomous functional module, independent
of our capacity to see, move, manipulate, reason, and perhaps even to speak.
The [Turing
test] itself is based on the pre-emptive assumption that our linguistic communication
capacity is functionally isolable" (Hamad 1992). DB2 might not even know that it's playing.
Kasparov probably plays because he enjoys chess and has the desire to win, while DB/s
8
actions are dictated and bounded by its pre-programmed
software. We cannot assume that
the robot, despite its technological excellence, does anything because it wants to.4
Moreover, even though DB2 has perceptual
capabilities,
it does not necessarily
have
any phenomenal experience of anything it senses, since the input is nothing more than
formal data.
In short, is it right to say DB2 is conscious? If a mind
is nothing more than
computation,
then there is no reason to believe DB2 doesn't have the potential to be. The
next section explores the concept and plausibility of the computational
nature of the mind.
IS A MIND A COMPUTER?
John Searle famously lectured:
Because we do not understand the brain very well we are constantly
tempted to use the latest technology as a model for trying to understand it.
In my childhood we were always assured that the brain was a telephone
switchboard. ("What else could it be?") I was amused to see that Sherrington,
the great British neuroscientist, thought that the brain worked like a
telegraph system. Freud often compared the brain to hydraulic and
electromagnetic systems. Leibniz compared it to a mill, and I am told some of
the ancient Greeks thought the brain functions like a catapult. At present,
obviously, the metaphor is the digital computer. [Quoted in Kurzweil 2005]
The way we understand the brain is correlated with the high-tech paradigm of the day, but
the idea of the computational
mind is nothing new. Thomas Hobbes contended that the
mind is the brain's function as a calculating machine:
"REASON ...
is nothing but Reckoning
(that is, Adding and Subtracting) of the Consequences of general
the marking and signifying of our thoughts" (Hobbes 1904/1651).
names agreed upon, for
Our mind is a mechanical
thinking machine, an infinitely complex flowchart of inputs and outputs.
4
This is a crucial theme in Blade Runner, which I will discuss later.
9
In mid-201h
century
Britain, Alan Turing set out to show that Hobbes was on to something.
imitation game," an original thought experiment
He designed "the
that attempted to solve the puzzle. The
game is simple. Three participants, a man, a woman, and an irrelevantly gendered
interrogator
participant
(A, B, and C, respectively) are placed in three rooms. The identity of each
is unknown.
They can communicate with each other freely through Teletype,
keeping revealing factors like tone of voice or handwriting
a mystery.
The object of the
game is for C to determine the sexes of A and B by asking each of them questions.
catch is that A attempts to mislead C by providing false information.
The
At the same time, B
attempts to convince C of the truth. If A successfully fools C, then A "passes" the test. Next,
replace A with a computer.
Band C remain human and don't know that A is a machine.
If A,
a computer, manages to convince C, a human, that it is in fact a human female, then Chas
met the criteria for intelligence (Turing 1950).
TURING TEST EXTPA CREDIT:
Turing held that if a human cannot distinguish a computer
from a person, then that computer can think and thus has a mind.
His
CONVINCE THE EXAMINER
THAT ti_CT; A COMPUTER.
conclusion helped give rise to computationalism, or the
computational
theory of the mind (henceforth CTM), the idea that
the brain is a computer, and mental states and consciousness
somehow arise from the formal processing. According to Turing and
Church, "anything that can be given a precise enough characterization
as a set of steps can be simulated on a digital computer,"
algorithmically,
a computer can implement
(Searle 2008, 87).
Figure 1 From xkcd.com
so if a mind can be transcribed
it, thus giving rise to machine
consciousness
If this is possible, the brain is just a biological UTM, or "wetware."
10
The computational
theory of mind is built on a theoretical framework called
functionalism, the idea that a mental state is defined by its function.
As an analogy, a
carburetor is a device whose primary function is to mix fuel and air in order to cause
combustion.
A carburetor can be made of any materials, just as long as that as it fulfills that
function; it is solely defined by its function.5
to this theory.
Mental states would be no different according
The functionalist argues that a mental state is nothing more than "its
function in mediating relations between inputs, outputs and other mental states" (Carter
2007, 45). For instance, a pain is defined by the role it plays. Some would argue that pain is
nothing more than tissue damage and C-fiber stimulation.6
To the functionalist,
a mind is a
Turing machine. Accordingly, a pain is an input (tissue damage), a mental state (discomfort,
anxiety, etc.), and an output (behavior).
The functionalist
holds that any system that can
iterate these conditions is in pain, regardless of composition.
biologically
The token example is the
and chemically different Martian who is in a pain state when it meets the
requisite pain conditions.
inputs, pain-alleviating
this functional
Pain "mediates relations between characteristic pain-inducing
reasoning and behaviour" (Carter 2007, 45). Anything that serves
role is a pain ex vi termini.
Computationalism's
aim is "fleshing out these mediating relations
question are held to be computations"
- the relations
in
(Carter 2007, 95). This is not to say, however, that
the mere operation of formal systems is sufficient for consciousness.
If this was the case, a
simple tape-based Turing machine is itself a thinking thing, an unsettling thought indeed.
5
The carburetor example is an adaptation of an argument used by Jerry Fodor
(Psychological Examinations, Random House 1968).
6
Also known as type-physicalism, as we shall see.
11
(Although some argue that there is "something
it is like" to be an inert artifact, as will be
discussed later, for now we shall assume the falsity of this claim).
sentience arises from the interplay between our computational
If CTM is true, however,
brains and our sensory
organs; the mind is the result of the operation of software while the brain and body are the
various pieces of hardware.
Granted, CTM proponents realize that there might be more to
cognition than just syntactic manipulation.
Just as long as "mental
states are
at least
computational states," CTM holds (Searle 2008, 87, my emphasis).
Functionalism7 and CTM turn on multiple realizability, the understanding that 11a
single mental kind (property, state, event) can be realized by many distinct physical kinds"
(Bickle 2008). If every minute detail of the brain, down to the very last neuron, was
reenacted with, say, beer cans, would a mind emerge? Douglas Hofstadter {2000) wrote "A
Conversation With Einstein's Brain," a thought experiment that explores this idea. Lets say
that one microsecond before his death, every detail of Albert Einstein's
brain was copied
exactly as it was into a book. Each of the hundreds of billions of pages corresponds to a
single neuron and information about its connections (synapses). When the real life Einstein
heard someone ask a question, he perceived the vocal utterances with his ears, which then
affects the auditory neuron structure in the brain.Theoretically, one could ask the
disembodied Einstein a question by correlating relevant information about how his brain
registers each particular tone and trace consequent chain reaction of synapses, which
eventually lead to Einstein uttering a response to the question. Perhaps a machine could
act as a middleman, speeding up the page turning. Is the brain-book a mind?: "I'm losing a
7
Here I refer to certain variations of functionalism, but not all. See Lewis 1991.
12
clear sight of who 'I' is. Is 'I' a person? A process? A structure in my brain? Or is 'I' some
uncapturable
essence thatfeels what goes on in my brain?" {Hofstadter 2000, 445)
Hofstadter's point is that the 'I' all of us are intimately familiar with is perfectly conceivable
as a set of algorithms, realizable in any implementing medium, inasmuch as the
unfathomably
complex programming is good enough.
If functionalism is correct, the mind-body problem is solvable with enough time and
energy spent on computational models of the brain. The ultimate goal of artificial
intelligence is to fully comprehend the human mind and create a unified theory of
consciousness. If such a theory is ascribed to an artifact, consciousness could presumably
arise. I do not believe that consciousness is or is not multiple realizable. My point is an
agnostic one; there is no test conceivable that can definitively prove whether consciousness
has been achieved. The Turing test, "though essential for machine modeling the mind, can
really only yield an explanation of the body" (Hamad 1992). Behavior alone is not sufficient
for mentality.
IS A COMPUTER A MIND?
If CTM is true, any UTM can implement a syntactic mind. Turing believed that the
mind is syntactic, and that the imitation game was an indicator of the presence of mind.
But what if CTM is false? If the human mind is not computational, is it still possible for a
computer to be conscious? Before we delve into the million-dollar question, I must first
clarify some key concepts and assumptions. Various writers across the gamut of philosophy
and science have different definitions of words like 'mind', 'consciousness', 'thinking', and
13
'intelligence'.
Let me clarify my own usage. I hold that the possibility for consciousness is a
necessary for mentality. For example, in a deep sleep one is decidedly unconscious, but
dream states are a form of consciousnesssince there is still some sort of phenomenal
experience taking place. But one cannot dream or think in the first place if there was never
any conscious experience to begin with. Thinking, or introspecting, is the active process of
exploring the contents of one's mind. Dreaming" is not thinking because it occurs passively.
Intelligence, on the other hand, does not presuppose mindedness. Cognitive
scientist Steven Pinker defines intelligence as "the ability to attain goals in the face of
obstacles by means of decisions based on rational (truth-obeying) rules" (Pinker 1997, 62,
my emphasis). The term 'Artificial Intelligence' is then, according to his definition, a
synthetic entity capable of following rules in order to attain goals. When I attempt to
control my car over an icy stretch, the anti-lock breaks automatically engage, helping me
avoid danger. In this case, the ice is an obstacle and the braking system follows a set of
rules in order to decide when to engage, accomplishing the ultimate goal of car and driver
protection. By Pinker's lights, the brakes on my car are intelligent. To say that my brakes
are conscious or have a mind, on the other hand, is a much stronger, and tenuous, assertion.
So what kind of artifact, if any, can think?
In 1956, computer scientist Allen Newell, economist Herbert Simon, and systems
programmer J.C. Shaw shocked the scientific community with what is considered the first
artificial intelligence program. "Logic Theorist," as it was called, managed to prove 38 of the
first 52 theorems from Whitehead and Russell's Principia Mathematica (Copeland 1993, 7).
8
Barring lucid dreaming, in which the dreamer is in active control of his or her situation.
14
This may not sound as impressive as "I am C-3PO, human cyborg relations,"
enough for Al researchers that a thinking machine might be possible.
but it was proof
Two years later,
Simon claimed that within ten years, computers will defeat the world champion chess
player {he was off by about thirty years), discover and prove a new mathematical theorem,
and, most importantly,
that "most theories in psychology will take the form of computer
programs," advocating CTM {Simon and Newell 1958, 6). By 1961, Newell and Simon were
ecstatically optimistic,
writing:
It can be seen that this approach makes no assumption that the 'hardware'
of computers and brains are similar, beyond the assumptions that both are
general-purpose symbol-manipulating devices, and that the computer can be
programed to execute elementary information processes functionally quite
like those executed by the brain. [Newell and Simon 1961, 9]
Al innovator Marvin Minsky concurred with Newell and Simon not long after, arguing that
brains are "meat machines" capable of duplication
(Dreyfus 1994, 252). The search for the
synthetic mind was well underway.
Fast-forward
to present day. There are no sentient robots roaming the streets or
running businesses. Critics of CTM and functionalism
argue that Al research has been
barking up the wrong tree. John Searle leads the attack on computational
arguments against "strong Al," the concept that an "appropriately
Al with his
programmed computer
really is a mind, in the sense that computers given the right programs can be literally said to
understand and have other cognitive states" {Searle 1980).
If strong Al holds, mental states
are invoked at least in part through syntactic computation.
Strong Al assumes the truth of CTM, but CTM does not necessarily assume strong Al.
"Weak Al" proponents hold that the brain is not necessarily computational,
15
but the study of
computationalism
as a psychological paradigm is scientifically useful.
The big difference
between strong and weak Al proponents is that while the former is convinced that the right
series of computations
invokes an actual mind, the latter holds that minds can be simulated,
but not duplicated. This distinction is crucial. If strong Al is correct, it is theoretically
possible to synthesize a mind. Any UTM could potentially
instantiate the unimaginably
complex array of naturally occurring algorithms resulting in a sentient artifact.
But is syntax
enough for a mind? Searle famously argued in the negative with the Chinese Room thought
experiment:
Imagine a native English speaker who knows no Chinese locked in a room full
of boxes of Chinese symbols (a data base) together with a book of
instructions for manipulating the symbols (the program). Imagine that people
outside the room send in other Chinese symbols which, unknown to the
person in the room, are questions in Chinese (the input). And imagine that by
following the instructions in the program the man in the room is able to pass
out Chinese symbols which are correct answers to the questions (the output).
The program enables the person in the room to pass the Turing Test for
understanding Chinese but he does not understand a word of Chinese. [Cole
2009]
The Chinese speaker outside the room (call her Mei) assumes that the person inside (call
him John) is fluent, and for good reason. John is so adept at using the manual and shuffling
through the boxes that he could quickly respond to any of Mei's input, regardless of
complexity.
For all intents and purposes, Mei is communicating
with a fellow fluent Chinese
speaker. But John is not fluent; "Chinese writing is just so many meaningless squiggles"
(Searle 1980). All he does is manipulate those squiggles according to a set of
predetermined
rules, or a "script."
16
It is contradictory
to say John understands Chinese when he doesn't actually
understand a word of it. Searle comes to a profound conclusion:
mental states have
semantic (meaningful) content, and syntax alone is not sufficient for semantics, so mental
states cannot be syntactical. The purely syntactical computer can emulate the mind, but not
duplicate it. He writes:
You can simulate the cognitive processes of the human mind as you can
simulate rain storms, five alarm fires, digestion, or anything else that you can
describe precisely. But it is just as ridiculous to think that a system that had a
simulation of consciousness and other mental processes thereby had the
mental processes as it would be to think that the simulation of digestion on a
computer could thereby actually digest beer and pizza. [Searle 2008, 68]
Searle finds it absurd to think a mind can be caused in this sense. Simulation
duplication.
is not
It might be possible in practice to simulate human intelligence on a computer,
"just as scientists routinely simulate everything from hurricanes and protein synthesis to
traffic jams and the black market of Albania," but the result is only an illusion of the original
(Haugeland 1985, 112).
Searle's point, that syntax is not sufficient for semantics, has become a mantra
amongst opponents of strong Al and CTM. The man in the room passes the Turing test,9 but
he lacks any semblance of semantic understanding.
meaningfulness.
'Understanding' is contingent
upon
When I understand a concept ('democracy', for example), the idea
becomes an object of my conscious experience.
9
I know what democracy means once I
Some might argue that the man in the Chinese Room cannot actually pass the Turing test if
asked questions like "What is time?" (see Ben-Yami 1993). I don't see the value in such
claims. There is no good reason to presume that the Chinese-English manual can't be
programmed to provide a conversationally acceptable answer like "the unextended
dimension of existence that determines the sequential nature of events."
17
attach to it some semantic content.
representation
thereof.
John has no intentional
To
understand something requires mental
This power of representation
is generally known as intentionality.
states about the actual meanings of the characters.
for him to think about the semantic content of the "conversation"
It is impossible
with the Chinese-
speaker. Of course, he can think, "well, maybe I'm talking about kittens," but such a
thought is a complete shot in the dark with no basis in understanding.
a Turing machine with the manual as its program.
The Chinese Room is
The argument shows that the Turing test
does not test for a mind, but simply for the existence of computational
processes.
The Chinese Room represents the syntactic processes by which computers "think."
Computers as we know them are programmed to do exactly what John does (albeit at
lightning fast speeds), devoid of intentionality,
understanding,
and semantic content.
A
computer may be able to simulate a mind, but not duplicate it. DB2, our perceptually
equipped, chess-playing robot does not have mental content at all, only brute-force
As might be expected, Searle's argument has garnered an enormous
criticism.
data.
amount of
Here I will address a few of the strongest instances. The response typically known
as the "Systems Reply" admits that the person in the room (John) in fact does not
understand Chinese, but that the entire system of inputs and outputs does understand.
John acts like the central processing unit of a computer; only one part of a larger whole.
The room itself, so to speak, is the fluent Chinese speaker with whom Mei communicates.
Searle rebuts by claiming that there is no reason to claim that John can't just memorize the
entire manual and learn to write and recognize every symbol, all while working outside.
18
The whole system is now completely internalized,
but John remains completely ignorant of
any semantic understanding.
The "Robot Reply" admits the validity of the Chinese Room but suggests an
alternative thought experiment.
Instead of manipulating
formal inputs and outputs
according to a script, we place a computer inside a mobile robot who, like our 082, is
equipped with perceptual apparatuses like microphones, cameras, touch sensors, etc. The
robot uses its senses to learn the world around it, just like a chlld.:" The robot is free to
learn Chinese independently
by forming a causal connection with the world.
Searle writes
in response:
Suppose that instead of the computer inside the robot, you put me inside the
room and, as in the original Chinese case, you give me more Chinese symbols
with more instructions in English for matching Chinese symbols to Chinese
symbols and feeding back Chinese symbols to the outside. Suppose, unknown
to me, some of the Chinese symbols that come to me come from a television
camera attached to the robot and other Chinese symbols that I am giving out
serve to make the motors inside the robot move the robot's legs or arms. It is
important to emphasize that all I am doing is manipulating formal symbols: I
know none of these other facts. I am receiving 'Information' from the robot's
'perceptual' apparatus and I am giving out instructions' to its motor apparatus
without knowing either of these facts. [Searle 1980]
Even though the external world is invoked in this situation, no semantics
the totality of the data is still formal.
can arise because
It only adds complexity to the man-in-the-room's task.
Although the Chinese Room argument has profound implications across the
spectrum, ultimately Searle begs his own question about the nature of the mind. He
10
This method of information processing is known as bottom-up Al, in contrast with topdown cognition, in which "it has been constructed according to some well-defined and
clearly understood fixed computational procedure ... where this procedure specifically
provides a clear-cut solution to some problem at hand" (Penrose 1994, 18).
19
contends that syntax is not sufficient for semantics and that the best computers can is
simulate consciousness {weak Al). However, he fails to address exactly what makes our
minds so special that they have semantics while computers cannot.
mind is fundamentally
He assumes that the
different than a symbol processing machine but never elaborates on
the nature of that difference.
His argument is based on three premises:
Pl: Programs {software) are syntactic and are thus self-contained
P2: Minds have semantics and are thus not self-contained
P3: Syntax is a not a sufficient condition for semantics
What's missing missing is the second half of P2. It isn't enough to simply say that
our thoughts have meaning and thus cannot be syntactical. What gives our thoughts
meaning in the first place? How does visible light detected by the eye or vibrations
of air in the ear canal mean anything to a mind? Perhaps meaning and intentionality
are just illusions caused by our brains but are really semantically empty (see Dennett
1991a). Or perhaps we aren't conscious at all, as some persistent eliminativists
contend.
Searle's argument is poignent but inconclusive.
The ultimate aim of this paper is to show that the Searl e's semantics will never be
fully understood.
The missing ingredient, why our mental states are meaningful, is beyond
the scope of human comprehension
for reasons I will address in the next two chapters.
Before we proceed, it is important to address one final criticism.
The Other Minds response
asks how it is possible to know if anybody understands anything besides judging by their
behavior.
doesn't?
If an android can fool anyone into thinking it understands, who's to say it
Searle's response goes as follows:
20
The problem in this discussion is not about how I know that other people
have cognitive states, but rather what it is that I am attributing to them
when I attribute cognitive states to them. The thrust of the argument is that
it couldn't be just computational processes and their output because the
computational processes and their output can exist without the cognitive
state. It is no answer to this argument to feign anesthesia. In 'cognitive
sciences' one presupposes the reality and knowability of the mental in the
same way that in physical sciences one has to presuppose the reality and
knowability of physical objects. [Searle 1980]
As sentient beings, it is impossible to deny the fact that we directly experience our own
consciousness (although the eliminativists
and others have tried). We also know that
computation
Using our own consciousness as a reference, we
can exist without cognition.
assume that other people have minds and phenomenal experience of the world but have no
reason to assume that they are computers.
This approach to the problem of other minds is
known as the argument from analogy.
However, the argument from analogy falls short. Just because something
acts like a
sentient being by no means necessitates consciousness. We
anthropomorphize
unconscious objects and nonhuman animals all the
time, sometimes attributing complex thoughts and emotions to entities
that are obviously incapable of them.
We think cats are happy when
they grin because that's what humans do (figure 2). In reality, the cat
Figure 2 Who are we to say this cat
is happy?
might be miserable or scared, but the tendency to humanity or sentience by analogy leads
us astray. My point is that analogy alone is not enough for the presence of other minds.
This plays a major role in the advancement of artificial intelligence theory and development.
A major barrier standing in its way is the inability to ever know, with full certainty, whether
21
or not a nonhuman entity is sentient.
In the next section, I will discuss this uncertainty
problem and its implications in philosophy, cognitive science, and Al research.
22
CHAPTER 2
THE ENIGMA OF FAMILIARITY
THE HARD PROBLEM
At this moment, I am sitting in a cafe typing on my laptop. I hear the distinctive
sound of fingers striking a keyboard over chatter of other customers and ambient piano
music. I shiver when the door opens, sending a chill through my body. The pastry in front of
me smells of butter and cinnamon, and I can feel myself salivating as I write about it. I feel
cheerful and jovial because yesterday I received an offer for a wonderful
job for next year.
have these experiences because I am sentient and aware, two defining characteristics of
consciousness, a barely understood but ubiquitous psychological phenomenon
immediately
familiar to all of us. As far as I know, humans have always been conscious and always will
be. Death and coma notwithstanding,
consciousness is a necessary
part of human
existence.
For this reason, consciousness as a concept is ironic.
It's been around for at least as
long as we have and without it, scientific study and epistemic
progression could never
happen. But in spite of countless hours spent in laboratories
and classrooms, a cohesive
theory of consciousness is yet to be discovered.
In fact, so little is actually known about it
that The International Dictionary of Psychology defines conscious as such:
23
Consciousness.
The having of perceptions, thoughts, and feelings;
awareness. The term is impossible to define except in terms that are
unintelligible without a grasp of what consciousness means. Many fall into
the trap of equating consciousness with self-consciousness - to be conscious
it is only necessary to be aware of the external world. Consciousness is a
fascinating but elusive phenomenon: it is impossible to specify what it is,
what it does, or why it evolved. Nothing worth reading has been written on
it. [Sutherland 1996, 95, emphasis added]
It is rare to find such candid language in a reference book. But how could it be true?
Bertrand Russell agrees: "The sciences have developed in an order the reverse of what
might have been expected.
What was most remote from ourselves was first brought under
the domain of law, and then, gradually, what was nearer: first the heavens, next the earth,
then animal and vegetable life, then the human body, and last of all (as of yet imperfectly)
the human mind" (Russell 1961). The boundaries of human knowledge are expanding at an
exponential rate, but the nature of what is most familiar to all of us remains vague and
misunderstood.
That is not to say that volumes worth of literature have not been written about it.
Cognitive science is devoted to the subject, synthesizing psychology, neuroscience,
philosophy, linguistics, anthropology,
interdisciplinary
and computer science into one contiguous,
area of study. Theories of consciousness abound from every field, and
great progress has certainly been made. In particular, the systematic mapping of brain
function and behavioral correlation
before. But the
has allowed us to know more about the brain than ever
mind still eludes us. Although science can explain how the senses function,
why this cinnamon bun
smells so damn good is a complete mystery. The inner experience
of the mind is private and subjective, knowable only by the knower and impossible to
describe in purely objective terms.
I can describe how I'm feeling to the best of my ability,
24
and you can try to relate using your own experience, but the two sets of data are
irreconcilable;
we can't know if they are the same. Individual conscious experience is so
distinct and accessible to us, yet so unbelievably opaque and foreign to another.
This is a crucial aspect of the mind-body problem in philosophy.
Descartes famously
contended cogito ergo sum, I think therefore I am, demonstrating the perspicuous,
undeniable existence of his own mind. He held that the physical world and mental world
were dualistic, comprised of two discrete substances, physical matter (res extensa) and the
non-extended, material soul or mind (res cogitans). Despite the currency of his words, the
cogito argument has become the butt of countless philosophy jokes, offered to freshman as
an exercise in argument analysis and refutation. Philosophy and science have become
inextricable, and there are no reputable empirical theories of the soul. Theology aside,
modern thought favors a naturalistic materialism, the idea that all that exists is matter and
all phenomena including consciousness can be reducible to phvsics.i! Materialism has been
successful in explaining the natural world, but inevitably fails to adequately account for
subjective conscious experience. A vast amount has been written both in defense of and in
opposition to materialistic consciousness,but the solution to the problem remains largely
unsolved.
Typically, the problems of consciousnessare split into two issues.12 The Easy
Problem is well under control by empirical science. It considers topics involving brain
behavior, the integration of information, and stimulus response, all within the realm of
11
Of course this is a very narrow and underdeveloped view of materialism. My own
position is in favor of a materialism in which consciousness is irreducible.
12
This is David Chalmers' idea, but it is widely accepted as a useful way to characterize
consciousnesstheory.
25
empirical study. The hard problem, as it is known, is much more of a challenge.
David
Chalmers describes it as
the problem
is something
sense - or is
something it
is something
of experience. Human beings have subjective experience: there
it is like to be them. We can say that a being is conscious in this
phenomenally conscious, as it is sometimes put - when there is
is like to be that being. A mental state is conscious when there
it is like to be in that state. [Chalmers 2002a]
What gives 'red' the quality of redness? After all, 'red' is nothing more than
electromagnetic
radiation of a particular wavelength and frequency, detected by the eye
and perceived by the brain. If everything in the universe is reducible to physics, then the
experience of 'red' is nothing more than that.
But this response is terribly
unsatisfying.
Our
senses have a phenomenal quality experienced by the mysterious "inner life" that frustrates
scientists to no end. Some choose to ignore the problem altogether, dismissing
consciousness as a trivial intuition:
The "intuition" at work here is the very raison d'etre of the problem of
consciousness. The only consistent way to get around the intuitions is to
deny the problem and the phenomenon altogether. One can always, at least
when speaking "philosophically," deny the intuitions altogether, and deny
that there is anything (apart from the performance of various functions) that
needs explaining. [Chalmers 1996, 110]
This approach is a mistake, of course, because every normally functioning human has an
inner life and disregarding it will lead us nowhere. This mysterious quality is at the core of
the hard problem of consciousness,and it is the modern day expression of the mind-body
problem.
Those who take a purely scientific approach may claim that consciousness is
reducible to its constituent physical properties. Emergentism, championed by Samuel
26
Alexander13
and C. Lloyd Morgan14 in the early
zo"
century, is the idea that consciousness
emerges from fundamentally simple brain processes. To illustrate, take water and break it
down to its constituent parts, oxygen and hydrogen. Without these two elements, water
cannot be. However, water is not an inherent property of oxygen or hydrogen. If there was
a world where oxygen and hydrogen exist as discrete elements but can never interact, that
world is necessarily devoid of H20. So oxygen and hydrogen are inherent to water, but not
vice versa. Similarly, consciousness emerges from neural processes even though
consciousnessis not an inherent property thereof:
To apply emergentism theory to a universal scale is to accept physical ism. Type
physicalism (aka identity theory of mind) is a materialistic position that holds that all mental
states and processes are equivalent to brain behavior and, as a result, consciousness is
reducible to physics. U.T. Place argued that consciousness might be a pattern of brain
activity that could be correlated with certain brain processesand that the elusiveness of
introspective observations could just be a "phenomenological fallacy." Introspection is just
brain behavior, just like lightening is just a high voltage, short duration electric charge (Place
2002). Herbert Feigl, another leading identity theorist, concurred, claiming "the states of
direct experience which conscious human beings 'live through,' and those which we
confidently ascribe to some of the higher animals, are identical with certain (presumably
configurational) aspects of the neural processes in those organisms" (Feigl 2002, 69).
13
See Alexander's Space, Time, and Deity (London: Macmillan, 1927)
See Morgan's Introduction to Comparative Psychology, 2nd ed., rev. (London: Walter Scott,
1903)
14
27
Mental states are contingent
upon specific brain states. In other words, "there is no mental
difference without a physical difference"
Is consciousness
reducible?
(Nagel 1998).
Many materialists of different stripes argue in the
affirmative. After all, if mental states aren't physical, what could they possibly be? Dualistic
philosophy allows for a mental "stuff" separate from physical substance,
fallen out of fashion in the face of scientific development.
but dualism has
Most contemporary
philosophers
of mind rely on physics and neuroscience for empirically proven evidence to support
argumentation.
As a result, the study of consciousness has become inextricably
science. However, I reject dualism but deny the validity of physicalism
about consciousness.
Subjective conscious experience is knowable only to the subject, and reduction
public data is impossible.
linked to
to objective,
The best we can do is correlate between brain states and
behavior. The next section analyzes some major arguments against physicalism
in order to
show its inadequacy as a coherent theory of consciousness.
ARGUMENTS FROM INEFFABILITY
In 1866, Thomas Huxley wrote: "What consciousness is, we know not; and how it is
that anything so remarkable as a state of consciousness comes about as a result of irritating
nervous tissue is just as unaccountable
his lamp" (Huxley 1866, 193).
philosophical
investigation,
as the appearance of the Djinn when Aladdin rubbed
Despite 150 more years of rigorous scientific
and
we still have no idea. Even Einstein is reputed to have admitted,
"Science could not give us the
taste of soup (Dennett 2002, 230). At the forefront of the
28
hard problem is the concept of qualia,
15
the technical term for the phenomenal,
felt
qualities we experience through the senses. Qualia like the taste of an apple, the roughness
of sandpaper, the rumbling of a basstone from a subwoofer, and the smell of a musty attic
can be experienced by anybody with normal perceptive abilities, but the mystery lies in
their subjective character. A piece by Stravinsky might sound like heaven to Jones and
cacophony to Smith. Both have normally functioning ears and a deep appreciation for
classical music. There is the matter of personal taste, of course, but it also must be
considered that Jones and Smith have different experiences of the same tones. Middle C is
always 262 Hz, but only I know what middle C sounds like to me.16
The problem is that our explanatory capacity is limited by the boundaries of natural
language.
!.SHt t•; ·.:>>Rr>..W.>t. \'tOW,
SM\;U .."'S ~\:: 00 \o'lc::.<:1'\ l~E..
11\J'I Y\'i::. crw.i:
THrc..~?
I '3~L1;> llt>.~t.
"-"IM.,t...'S
~'<{ti
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G~SC.\l',~.£
H"-~£.
' ·~o-;
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Figure 3 Borrowed from Chalmers
15
115 A. \.lliL'i:.
811\JHI<.'{. S\l~
THE \.OW
~\l!l,\\)'1\'f
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1996
As Chalmers 1996 notes, qualia, experience, phenomenology, phenomenal, what it is like,
subjective experience all refer to the phenomena privy to the conscious mind. Only
grammatical differences set them apart.
16
The inherent differences between Smith and Jones return later in my discussion of
inverted qualia.
29
In figure 3, Hobbes the tiger describes his olfactory experience of fire with words like
snorky, brambish, and brunky. To his friend Calvin, such terms are as meaningless as the
squiggles and squoggles in the Chinese Room. Only Hobbes knows precisely
what they
mean because only he has direct access to the contents of his inner experience.
Even
another verbal, sentient tiger with the same sensory faculties cannot know if its experience
of "snorky" is the same as Hobbes' because verbal explanation is inadequate.
concepts like 'green' through ostensive definition,
the repeated pointing to green objects by
others and labeling them such. I can identify green objects because
instilled in me through ostensive definition.
We learn
'green' has been
Hobbes thinks fire smells snorky because he
taught himself to identify a particular odor with that term.
No one, even his best friend
Calvin, can ever know exactly what Hobbes means when he calls something
'snorky' or
'green' or anything for that matter because of the private, enclosed, and ineffable nature of
conscious experience.
Or, to use a literary example, take the following dialogue from Brideshead Revisited
between the narrator Charles Ryder and his friend Sebastian Flyte as they drunkenly
describe the taste of a wine.
"It is a little, shy wine like a gazelle."
"Like a leprechaun."
"Dappled, in a tapestry meadow."
"Like a flute by still water."
" A wise old wine."
" A prophet in a cave"
" A necklace of pearls on a white neck."
"Like a swan."
"Like the last Unicorn." [Quoted in Lanchester 2008]
30
Boozy shenanigans aside, Ryder and Flyte certainly experience something that compels
them to describe the wine in such comically distinctive ways. However, even if I do know
what pearls on a white neck actually tastes like (assuredly, I do not), I will never know what
it is like for Ryder to experience such a sensation.
Much of Wittgenstein's philosophy is couched in the limitations of natural language.
In §293 in Philosophical Investigations he writes:
Suppose everyone had a box with something in it: we call it a 'beetle'. No
one can look into anyone else's box, and everyone says he knows what a
beetle is by looking at his beetle. Here it would be quite possible for
everyone to have something different in his box. One might even imagine
such a thing constantly changing. But sup- pose the word 'beetle' had a use
in these people's language? If so, it would not be used as the name of a thing.
The thing in the box has no place in the language-game at all; not even as a
something: for the box might even be empty. No one can 'divide through' by
the thing in the box; it cancels out, whatever it is. [Wittgenstein 1974]
"Wittgenstein's Beetle," as this thought experiment is commonly referred, shows that our
explanatory capacity is limited by natural language. The beetle represents the picture we
form in our minds when we think about or perceive something. Everybody's beetle might
be completely different, or they might all be the same. The point is that no one will ever
know for sure. Simply describing what it is to someone else is insufficient for intelligibility
because the only reference point available is my own beetle. I have a beetle and you have a
beetle, but mere linguistic congruence alone does not give rise semantic equivalence.17
Another treatment of this issue is known as the inverted spectrum argument, dating
back to John Locke's18 1ih century empiricism. If two people with normally functioning
17
It should be noted that Wittgenstein's philosophy of mind is not in line with my own.
However, his Beetle example is still pertinent to my argument.
18
See Locke 1689/1996, 169.
31
visual faculties observe a fresh strawberry,
both inevitably describe it as red.
there is the distinct possibility of the qualia of both observers to be completely
in this case, inverted.
Who is to say Smith's red is not Jones' green?
entire life perceiving red qualia as green qualia, for him, green
However,
different, or
If Jones spends his
is red. In theory, remapping
whatever neurological apparatus pertain to color perception can stimulate this situation,
but for the sake of argument, the logical possibility of inverted qualia is sufficient. The
question is whether it is empirically possible to prove veracity of the situation.
I argue later
that it is not.
In same vein as the inverted spectrum, Frank Jackson and Thomas Nagel argue for
the necessity of qualia and dispute physicalism with what is known as the knowledge
argument. In his famous thought experiment, Jackson supposes that Mary, the world's
foremost expert on neuroscience, spends her entire life in a monochrome room and has
never been exposed to any color other than black, white, and shades of gray. She has
always worn opaque, black stockings, a white lab coat, and black gloves. Even though she
knows more than anyone else about the physical processes behind color perception, there
is nothing Mary can do (short of taking drugs) to experience what color is like.
'Blue' means
nothing more than a 475nm wavelength, and will always mean that unless she ever leaves
the room. The physical facts behind a particular aspect of subjective experience are not the
same as the experience itself. When Mary is released and actually sees the blue sky for the
first time in her life, she learns what subjective color experience is. Even though she knew
every physical fact there is to know about color and human perception, her knowledge was
incomplete. Mary learns something an objective physical fact could not teach her. Jackson
32
shows that "physicalism leaves something out" something unaccounted for by objective
data (Jackson 1982).
A real-life take on Jackson's conclusions comes from a 2008 article in The New
Yorker. Here are two molecules, identical in every way except that they are inverted on the
y-axis:
0
0
Figure 5
Figure 4
Any competent chemist can fully understand the molecular structure of both examples, and
modern science can tell us everything else we could possibly know about them. Well,
everything except for the fact that Figure 4 smells like spearmint, while Figure 5 smells like
caraway, two completely disparate and distinct odors. When it comes to phenomenal
experience, we are baffled: "When scientists create new molecules in the laboratory,
they
may know every detail of a molecule's structure yet have no clue about what it will smell
like." Physical ism falls flat when it comes to the hard problem; it "risks missing the
fundamental
truth of all smells and tastes, which that they are, by definition,
experiences"
(Lanchester 2008, 121).
Coming to the same conclusion, Thomas Nagel's take on the knowledge argument
tries to imagine what it is like to be a bat. As we know, the sensory faculties of bats and
33
humans are much different.
Bats rely on echolocation
or sonar, emitting high-frequency
shrieks and perceiving the world around them through the reflection
of the sound.
Echolocation is incomparable to any human faculties and is thus unimaginable;
"though
clearly a form of perception, it is not similar in its operation to any sense that we possess,
and there is no reason to suppose it is subjectively like anything we can experience or
imagine" (Nagel 1979). I suppose I could blindfold myself and try to find my way by yelling
and carefully listening for an echo, but it still wouldn't be the same since bats don't hear like
we do. Furthermore, to imagine having webbed arms, eating insects, having poor vision, or
spending the daytime sleeping upside down is to imagine bat behavior from the point of
view of a human, not bat experience, and these concepts are surely not the same. In short,
it is impossible to conceive of what the inner life of a bat might be like.
Nagel chose bats because they are mammals and are thus relatively close to humans
phylogenetically.
19
He assumes, controversially,
that, like humans, bats are
on some level conscious and aware of their own being.20 However, while it
isn't difficult to imagine what it might be like to be another person,21
are strange enough to be utterly unfathomable.
bats
I know what it feels like to
hear Bohemian Rhapsody, so it is within my realm of imagination to think
Figure 6
about what it might be like for someone else to hear the same song. Humans are
19
See Janzen 2006; Hacker 2002
Nagel does not mean to say that bats fly around soliloquizing, of course. He merely
means that there must be something it is like to be a bat in a comparable sense that there is
something it is like to be a person.
21
Of course such a feat is impossible to perform accurately; subjective conscious experience
is private and inaccessible. But considering how all (normally functioning) humans share
the same perceptual and cognitive capacities, imagining what it might be like to be
20
someone else is possible.
34
cognitively closed to the possibility of imagining sonar perception. Thus, we are inextricably
tied to our own experiences and utterly incapable of conceiving of anything beyond our
perceptual horizon.
Unless the Batboy story in the Weekly World News (Figure 6) is true, no
human can imagine the experience of bat qualia.
The bat brain, on the other hand, is perfectly understandable,
"a domain of
objective facts par excellence - the kind that can be observed and understood"
within the
limitations of our own perceptual horizon (Nagel 1979, 172). Science informs us about our
own brains and bat brains in the same ways. We can analyze brain states by correlating
brain activity with patterns of observable behavior; such methodology is the backbone of
neuroscience.
experience.
However, neural correlation ignores qualia, the hallmark of conscious
Exactly what it is like to be a bat is an ineffable property knowable only by a
bat, and no amount of raw data about brains and behavior can change that.
Nagel
contends:
Without consciousness the mind-body problem would be much less
interesting. With consciousness it seems hopeless. The most important and
characteristic feature of conscious mental phenomena is very poorly
understood. Most reductionist theories do not even try to explain it. And
careful examination will show that no currently available concept of
reduction is applicable to it. Perhaps a new theoretical form can be devised
for the purpose, but such a solution, if it exists, lies in the distant intellectual
future. [Nagel 1979, 166]
In short, the subjective character of consciousness is an unavoidable obstacle for any
discipline involving the study of the mind. He challenges physical ism to stop skirting the
qualia issue by conceding ignorance or giving up entirely.
Nagel's point is that the peculiar and ineffable nature of first-person
incompatible with any sort of objective standpoint.
35
experience is
Nagel blames these disharmonious
standpoints for causing "many of the basic problems of philosophy: we are torn between
these two ways of seeing the world and cannot satisfactorily
conception of things," and current cognitive-philosophical
integrate them into a coherent
theories are inadequate means of
reconciliation {McGinn 1997b, 89}.
Another way to think about how to explain qualia and consciousness is by imagining
a being completely devoid of phenomenal experience. David Chalmers does so by talking
about zombies. Not Hollywood zombies, per se, but philosophical
zombies (p-zombies) who
have no appetite for brains and look just like regular people. P-zombies are exact physical
copies of people, down to every last atom, neuron, and synapse. My p-zombie twin is
indistinguishable
from me not only in appearance but also in behavior.
My own mother
wouldn't be able to tell us apart. The key difference between us is that my p-zombie twin is
completely devoid of conscious experience.
Even though he (it?) displays what seems to be
conscious behavior, there is an utter lack of phenomenology.
When my p-zombie twin
enjoys a freshly baked chocolate chip cookie (my favorite}, all the same physical processes
occur when I eat the same cookie. But there is no actual taste experience occurring, only
overt behavior.
There is nothing it is like to be a p-zombie.
This is a difficult position to defend, however, and there are compelling
counterarguments
standing in the way. For starters, any molecule-for-molecule
conscious person would surely be conscious. Unless some sort of panpsychism22
Cartesian dualism is correct, it is undeniable that the configuration
molecules comprising a person must have some determining
22See
Nagel 1979.
36
replica of a
or
and quantity of
effect on the existence of
conscious experience.
If consciousness is contingent on the physical, then the x number of
molecules in orientation y must cause awareness in my p-zombie twin because it does so
for me. Chalmers skirts this issue by simply positing a p-zombie world parallel to ours; "the
question is not whether it is plausible that p-zombies could exist in our world, or even
whether the idea of a p-zombie replica is a natural one; the question is whether the notion
of a p-zombie is conceptually coherent"
actually having a phenomenologically
(Chalmers 1996, 98). Of course the chances of me
absent p-zombie twin are extremely
Chalmers argues that its existence is logically possible.
unlikely, but
If the logical possibility of p-zombies
is true, then consciousness cannot be broached from a third-person viewpoint,
strengthening the knowledge argument and frustrating cognitive scientists
thus
even further.23
The logical possibility of zombies illustrates the point I aim to advance. There is no
way for me (or my mother) to know that my zombie twin is actually a zombie.
physically, functionally,
Because he is
and behaviorally identical to me, no test could definitively
apart. Now lets assume that computationalism
tell us
is false and that consciousness cannot arise
from formal processing. Android Andrew has a computer brain and looks, functions, and
behaves just like me. In short, Android Andrew is my zombie twin. If we both took the
Turing test, both of us would perform equivalently,
purposes, identical.
because we are, for all intents and
As we shall see, consciousness falls outside the realm of human
explanatory capacity and as a result, no test devised by humans could be comprehensive
enough to verify the existence of a sentient mind.
23
See Chalmers 2002b.
37
On a related and more lighthearted
note, when I was very young I climbed out of
bed, made my way down the hall to the master bedroom, and awakened
my mother.
"What's wrong?" she asked, to which I responded, "I think I have a finger infection." Since I
was still at the age when curiosity and ignorance often leads to personal injury, my
concerned mother turned on the light and examined my finger. "Nothing seems wrong,
dear. Are you sure it's your finger?"
"Maybe it's my hand, or maybe my ... " Before I could
finish my sentence I proceeded to vomit all over my parents' bed. Torn between laughter
and frustration, my mother informed me, "The word is 'nauseous'.
you are nauseous, honey."
When you feel that way
But remember, just because I didn't have a word for it, I was still
nauseous. There is a disconnection
between verbal description and phenomenal
experience. As we shall see later, this division is known as the explanatory
crucial aspect to consciousness theories across various fields.
38
gap and is a
CHAPTER THREE
DO ANDROIDS
DREAM OF ELECTRIC SHEEP? WE'LL NEVER
KNOW FOR SURE
THE EXPLANATORY GAP
In quantum physics, the Heisenberg uncertainty principle states that it is impossible
to know with precision the simultaneous position and momentum of a physical system. We
can know one or the other, but run into problems when we try to put them together.
Consciousnesstheory falls victim to a similar problem. Introspection gives us accessto the
brilliant world of qualia and phenomenal experience but tells us nothing about our internal
processesunderlying our inner life. Conversely, external observation has provided us a
wealth of information about how the brain works and interacts with the body. But it tells us
nothing about what it is like to be the test subject.
This fundamental divide is known as the explanatory gap. Joseph Levine coined this
term in support of Nagel and the knowledge argument. Take three propositions: (1) 'Pain is
the firing of C-fibers', (2) 'Heat is the motion of molecules', and (3) 'To be in pain is to be in
state F'. (2) is true by necessity; there is "no possible world in which [it is] false" (Levine
2002, 354). Heat is, by definition, the motion of molecules, so any other definition simply
wouldn't be heat. However, there is a "felt contingency" about statements (1) and (3); it is
conceivable to imagine pain without C-fiber firing and pain without being in a particular
39
functional state.
The sensation
of pain is the pain, so we can imagine a world with no C-
fibers but a phenomenon equivalent to what we know as pain. Unlike the heat example, no
distinction between the appearance of a phenomenon and the phenomenon itself can be
drawn. The reason why heat and pain cannot be explained in the same way comes down to
identity.
If what it's particularly like to have one's C-fibers fire is not explained, or
made intelligible, by understanding the physical or functional properties of Cfiber firings - it immediately becomes imaginable that there be (-fiber firings
without the feeling of pain, and vice versa. We don't have the corresponding
intuition in the case of heat and the motion of molecules - once we get clear
about the right way to characterize what we imagine24 - because whatever
there is to explain about heat is explained by its being the motion of
molecules. So, how could it be anything else? [Levine 2002, 358, footnote
added]
The proposition "heat is the motion of molecules" and its contingent corollary express a
particular identity that is fully explainable, leaving out nothing of importance.
Our scientific
knowledge can perspicuously explain how molecular motion causes the phenomenon
known as heat. The pain statement, on the other hand, leaves an explanatory gap between
the causal role of C-fiber firing and the way pain feels.
Both physicalism and functionalism fail to account for this gap. And since the gap is
left unexplained, consciousness is not intelligible in the same sense that 'heat is the motion
of molecules' is. For a proposition to be intelligible, "demand for further intelligibility
24
is
One might ask, "What about how heat feels? Isn't that just as unexplainable as pain
sensation? The answer to this question is yes, but the ineffability of heat experience is not
what Levine was driving at. His point is that the science behind the transfer of heat is fully
understood and is taken as a "primitive, brute fact about the universe," much like that value
of the gravitational constant G is fully understood to be 6.67428x10-11 N (rn/kg]". In both
cases, "there is nothing more we need to understand" (Levine 2002, 356).
40
inappropriate"
in that there is nothing left to be explained about it (Levine 2002, 357). 'Pain
is the firing of C-fibers' is not intelligible because of the necessity of further
explanation.
As shown in the previous chapter, physicalism only accounts for third-person
observable behavior.
We can induce pain in test subjects and observe the physiological,
neurological, and behavioral responses. But such experiments tell us nothing about the
first-person experience of consciousness: "Even hi-tech
us the physical basis of consciousness,
instruments
like PET scans only give
not consciousness as it exists for the person whose
consciousness it is" (McGinn 1999, 48). Heat caused by molecular motion is fully
explainable in physical terms alone; there is no explanatory gap dividing the proposition
'Heat is the motion of molecules'.
As for pain, the best we can do is correlation between C-
fiber firing and pain behavior, while the intermediate
phenomenological
experience is left
unexplained.
Functionalism, the basis for the computational
theory of mind, fails to explain
consciousness as well. Instead of identifying consciousness as physical processes,
functionalists
identify it by its causal roles. Pain, explained by functionalism,
is "a higher-
order property of physical states which consists in having a certain pattern of causes and
effects, as it might be mediating bodily injury and avoidance behaviour" (McGinn 1991,
209).
By these lights, the brain is just a UTM, so pain is the brain state mediating
inputs and outputs.
configuration.
relevant
Pain is thus realizable in any medium insofar as it is in the correct
A robot that implements the causal properties of pain is in pain according to
the functionalist model.
41
Functionalist definitions of mental states are not necessarily false, but they are
insufficient for a comprehensive
vital to a full understanding,
back to Chalmers' P-zombies.
explanation of consciousness. The causal role pain plays is
but the phenomenological
aspect is left gaping open. Think
They are functionally equivalent to humans; when they stub a
toe they cringe just like the rest of us. But in the end, all that occurs is pain behavior.
there is nothing it is like to be a zombie, under no circumstances
anything.
does the zombie
Since
feel
We know what pain is because we experience it intimately within our inner lives,
but "because the qualitative character itself is left
functionalist
unexplained by the physicalist or
theory that it remains conceivable that a creature should occupy the relevant
physical or functional state and yet not experience qualitative character" (Levine 2002,
359). Accordingly, pain is more than just the functioning of input and output mechanisms.
As Irving Krakow argues, functionalists
"talk about pain, but they ignore the reality that the
felt quality of pain is conceptually independent
of the empirical possibility
that the
neurological correlate of pain qualia might play the 'causal role' they want to attribute to
those qualia" (Krakow 2002, 97). The unmistakable feeling of pain is what mediates input
(tissue damage) and output (pain behavior), and that phenomenological aspect is
completely ignored.
Krakow quotes Wesley Salmon's explanation of causal interaction:
Let Pl and P2 be two processes that intersect with one another at the spacetime point S, which belongs to the history of both. Let Q be a characteristic
that Pl would exhibit throughout an interval (which includes subintervals on
both sides of Sin the history of Pl) if the intersection with P2 did not occur;
let R be a characteristic that process P2 would exhibit throughout an interval
(which includes subintervals on both sides of Sin the history of P2) if the
s
intersection with Pl did not occur. Then the intersection of Pl and P2 at
constitutes a causal interaction if: (1) Pl exhibits the characteristic Q before
42
S, but it exhibits a modified characteristic Q' throughout an interval
immediately following S; and (2) P2 exhibits a modified characteristic
throughout an interval immediately following S. [Krakow 2002, 76]
R'
In the case of pain caused by a stubbed toe, Pl is my brain as it functions normally, say,
while walking through a doorway and P2 is the act of my bare toe unexpectedly
doorframe.
striking the
Pl and P2 intersect at time S, and their intersection causes Q (characteristics
the brain while not in pain) to switch to Q' (characteristics of the brain while
of
in pain), as
well as R (my toe not striking the doorframe) to switch to R' (my toe striking the
doorframe).
This functionalist
explanation of pain accounts for all observable
involved in pain function, but still fails to account for first-person
experience.
behavior
The pain itself
(as opposed to its causal or behavioral correlates) cannot be treated as Pl or P2 because it
cannot be pinpointed
spatially. It is an unobservable, non-spatial property that exists solely
within the mind. As we shall see in the proceeding section, in addition to the problems of
irreducibility
and ineffability,
the issue of spatiality is major barrier to closing the
explanatory gap because human knowledge is bounded by space-time.
MCGINN'S THEORY OF COGNITIVE CLOSURE
According to legend, when Louis Armstrong was asked to explain what jazz is, he
responded, "If you gotta ask, you ain't never gonna know." A musicologist could give a
textbook definition of jazz and Mr. Armstrong himself could do his best to describe it. But in
the end, jazz is intelligible only after it is experienced first-hand.
Much to the chagrin of
cognitive scientists, the same principle applies to consciousness.
Levine argued for the
existence of an explanatory gap dividing first-person
43
subjective experience
and objective
scientific facts about cognition and Nagel pointed out that such a schism will forever
alienate proponents of both sides: "Absurdity comes with the territory, and what we need is
the will to put up with it" (Nagel 1986, 11). Only recently have some maverick philosophers
come out and flatly admitted that mind-body problem is an unsolvable
endeavor.
Arguments from every imaginable angle abound, but we are no closer to solving the hard
problem then we ever have.
Such a viewpoint, typically called New Mysterianism
(henceforth
NM), can easily be
dismissed as meager defeatism and that the problem will eventually be solved with enough
time and energy devoted to its solution.
Steven Pinker,
a recently converted mysterian,
explains the core tenets:
And then there is the theory put forward by philosopher Colin McGinn that
our vertigo when pondering the hard problem is itself a quirk of our brains.
The brain is a product of evolution, and just as animal brains have their
limitations, we have ours. Our brains can't hold a hundred numbers in
memory, can't visualize seven-dimensional space and perhaps can't
intuitively grasp why neural information processing observed from the
outside should give rise to subjective experience on the inside. This is where I
place my bet, though I admit that the theory could be demolished when an
unborn genius--a Darwin or Einstein of consciousness--comes up with a
flabbergasting new idea that suddenly makes it all clear to us. [Pinker 2007]
NM is potentially the most realistic prognosis around;
materialism is an eminently
philosophy except for its treatment of consciousness and functionalism
Colin McGinnis
defeatist.
agreeable
is a non-starter.
at the forefront of the NM movement, and he defends his view as non-
His goal is to figure out precisely why it is that we can't understand
consciousness,
not give up on it entirely:
Consciousness depends upon an unknowable natural property of the brain.
What this means is that I am not going to try to reduce consciousness to
those mundane known properties of neurons that materialists hope to get by
44
with. But neither am I going to conceive of consciousness as something apart
from the brain, something with no further analysis or explanation.
Consciousness is rooted in the brain via some natural property of brain
tissue, but it is not explicable in terms of electrochemical processes of the
familiar kind. [McGinn 1999, 43]
We can't deny the possibility that we are cognitively incapable of fully understanding
consciousness. Perhaps the solution we seek is part of the problem; the hard problem
might be beyond the realm of what is humanly possible.
I do not reject materialism, but simply ignoring or attempting to eliminate qualia is
insufficient.
Qualia are an undeniable aspect of conscious experience and are crucial to any
discussion about the hard problem.
materialism"
Chalmers calls my position "Don't-have-a-clue
since I believe qualia are caused by physical processes, but cannot be
explained as such. The mind-body problem is unsolvable, qualia will never fully be
understood, and we will never know if an artificial intelligence ever achieves sentience.
In short, there is no conceivable bridge for the explanatory
is correlation.
PET scans can measure brain activity, allowing
brain states with exhibited behavior.
gap. The best we can do
scientists to match particular
For instance, a 2001 study measured the brain
function of twelve members of the Free Evangelical Fundamentalist Community, a religious
group in Germany.
Each subject reports to have experienced transcendent experiences
during religious recitation.
Brain activity was measured during an intense prayer session,
and the results showed that religious experience "activated a frontal-parietal
composed of the dorsolateral
circuit,
prefrontal, dorsomedial frontal and medial parietal cortex"
(Azari, et al. 2001). The neural data is then correlated with the subjects' verbal descriptions
of their own experiences in order to understand exactly what happens in the brain during
45
prayer activity. There is no doubt that this sort of experiment
properties of brain function. To physicalists and functionalists,
full understanding of consciousness.
helps explain certain
correlation
I disagree because, as discussed
of natural language restrict us from comprehensively
is sufficient
for a
earlier, the limitations
explaining first-person
experience.
Neural correlates to verbal descriptions plus observable behavior is not comprehensive;
results of such studies fail to explain why we have phenomenal experience.
explanatory gap remains in between objective data and first-person
the
The
experience.
But what exactly is the limiting factor that restricts us from a materialistic
understanding of the mind? McGinn argues that human understanding is cognitively closed
to certain aspects of the universe, consciousness being the prime example:
The materialists are right to think that it is some property of the brain that is
responsible for consciousness, but they are wrong in the kind of brain
property they select. The dualists are right to doubt that the brain as
currently conceived can explain the mind, but they are wrong to infer that no
brain property can do the job. Both views overestimate our knowledge of
mind, and brain, presupposing that our current conceptions are rich enough
to capture the essence of the mind-brain link. I maintain that we need a
qualitative leap in our understanding of mind and brain, but I also hold that
this is not a leap our intellectual legs can take. [McGinn 1993, 28-29]
Our "intellectual
legs" can only stretch so far. The notion that humans possess the capacity
to know everything there is about the universe is a wild assumption that should not be
accepted out of blind anthropocentric
arrogance.
Since technology progressed at such an
alarming rate over the last century, this assumption is widespread.
on the moon, high-tech communication
After all, we put a man
computers (read: mobile phones) in our pockets,
and artificial organs in our bodies. What can possibly limit our epistemic growth?
46
In 1965, Intel co-founder
technological achievement
Gordon Moore charted
the progression of human
over time, leading him to conclude,
incorporated in a chip will approximately
"The number of transistors
double every 24 months" (Intel.com).
Recent
studies show that Moore's predicted rate of progression is actually slower than reality;
according to University of Washington professor Edward Lazowska, "The ingenuity that
computer scientists have put into algorithms have yielded performance
improvements that
make even the exponential gains of Moore's Law look trivial" (Lohr 2011). Arguably the
most optimistic technologist
around is Al innovator Ray Kurzweil.
book The Singularity is Near, by 2023 one thousand dollars
According to his recent
will buy the processing
capacity25 of a human brain. By 2059, one cent will buy the computational capacity of the
entire human race (Kurzweil 2005). He contends that every aspect of consciousness
well understood by science and completely explainable
advances in computational
technology.
will be
in objective terms, all because of
We shouldn't worry about the hard problem for
much longer; computers will eventually close the explanatory
gap.
What Kurzweil and his supporters must realize is that human cognition is not
unlimited.26 There are certain concepts we might never grasp simply because of an
epistemic horizon. To illustrate, look at the graph of the mathematical
(Figure 7). The function is asymptotic, meaning it will grow indefinitely,
function/(x)
= 1/x
but will never cross
25
The key word is 'processing'.
His claims only have merit insofar as CTM holds and the
brain is a computational entity.
26
Actually, Kurzweil would not disagree with this point. He claims that computers and Al
will eventually augment human knowledge. Without the aid of technology, " ... the
architecture of the human brain is ... profoundly limited. For example, there is only room for
about one hundred trillion interneuronal connections in each of our skulls ... Machines will be
able to reformulate their own designs and augment their capacities without limit" (Kurzweil
2005, Amazon Kindle Location 692)
47
either axis. The progression of human knowledge is asymptotic
this horizon, in that there are naturally
capacity that cannot be breached.
about
imposed limits on our cognitive
"No finite mind could encompass all of
space and time," McGinn writes; accordingly so, a solution
to the mindFigure 7
body problem lies out of reach beyond the axis (McGinn 1999, 33).
Human cognitive understanding is limited to concepts that are explainable in terms
of space and time. Our universe is multidimensional; space has three dimensions and time
has one. Conceiving of a dimension other than space-time is only possible through
theoretical physics, but introspectively imagining such a world is impossible.
This is because
the entirety of our experience is spent interacting within these dimensional boundaries,
barring certain accounts of certain psychotropic drug experiences, of course.
Perception
occurs when our sensory faculties register stimuli in the world around us, and transmit
them as electrical impulses to the brain, thereby giving rise to a particular
phenomenological sensation. What is perceived is immediately apprehensible through
introspection, or as it is commonly called, the mind's eye. When I perceive a chair sitting
five feet in front of me, the image of the chair and whatever else is immediately perceivable
are the objects of my consciousness. The same applies to when I am imagining a chair even
when there isn't one present, or when I am dreaming, or hallucinating. Regardless of
circumstance, the locus of attention is the object of consciousness.
The object of consciousness is non-spatial; the chair I am looking at is extended in
space but my mental projection is not. We can say that the concurrent brain activity occurs
in a physical space (i.e. in the visual cortex, an inch from the back of the head, in three
48
dimensions, etc.), but the felt experience itself has no measurable volume, location,
mass,
or shape; "It falls
under temporal predicates and it can obviously be described in other ways - by specifying
its owner, its intentional
content, its phenomenal character," but there is no spatial
dimension to consciousness (McGinn 1997a, 98).
The unembodied
nature of consciousness is what causes problems for empirical
science. There is a disconnect between the non-spatiality
nature of the external world.
of consciousness and the spatial
The property distinctions between the extended world with
the unextended mind has been at the root of the mind-body problem since Descartes.
McGinn seeks to revitalize and update the Cartesian dilemma:
nonspatial phenomenon,
human thought is fundmamentally
"While consciousness is a
governed by spatial modes of
representing the world, so that our ways of thinking tend to force consciousness onto a
Procrustean bed of broadly Euclidean design" (McGinn 1997b, 108). The objects of
consciousness are perceptually
experience.
inaccessible; observing the brain says nothing
about
Consciousness is thus perceptually closed, meaning we expound it in terms of
the physical.
It is safe to say that the object of consciousness is perceptually closed and is only
accessible through introspection.
However, perceptual closure does not entail cognitive
closure. Electrons exist, surely, even though it is impossible
very act of observation
to measure them because the
alters the electron's path. We can't observe genes, quarks, or atoms
either but we can postulate them because the explanability of other observable phenomena
depends on their existence.
For example, trait inheritence can be observed but cannot be
49
explained without genes. There is enough observable evidence {like DNA molecules) to
confirm the legitimacy of genetics without ever actually perceiving
a gene; "We can infer
hidden structure to explain what overtly appears" {McGinn 1999, 141).
But consciousness is a different story. Inference is not a sufficient condition for a
comprehensive explanation of first-person experience.
Define Pas the set of empirically
evident brain properties that clarifies the hard problem and fully explains consciousness.
McGinn contends that P cannot be infered like genes and electrons because of the
homogeneity that constrains sets of data:
Inference to the best explanation of purely physical data will never take us
outside the realm of the physical, forcing us to introduce concepts of
consciousness. Everything physical has a purely physical explanation. So the
property of consciousness is cognitively closed with respect to the
introduction of concepts by means of inference to the best explanation of
perceptual data about the brain. [McGinn 1991, 13]
Attempting to explain phenomenal consciousness with observable data is like
comparing apples and oranges; the two sets of information are inherently
incompatible.
Physical concepts cannot describe psychological concepts and vice
versa. Neural correlation
experiments show us nothing but patterns of behavior
and
concurrent brain states.
As Levine argued, observable data is fully explainable in physical terms, constrained
homogenously.
It is a brute, empircally provenfact that the gravitational contant G is
6.67428x10-11 N (rn/kg}"
However, attempting to explain Gin phenomenological terms is
scientifically meaningless. Yes, I can feel the affects of gravity upon my body and the
objects I interact with, and sure, I can do my best to verbally describe how it feels to
50
not be
floating above the ground." but the explanation is incomplete without physical
proof.
Consciousness is homogenously constrained in the same way: "Our modes of concept
formation, which operate from a base in perception and introspection,
cannot bridge the
chasm that separates the mind from the brain: They are tied to the mental
terms
and physical
of the relation, not to the relation itself" {McGinn 1997b, 106).
Since we can't explain conscious phenomena in terms of the physical, and
introspective analysis is unexplainable
because of the limits of natural language, it follows
that humans are cognitively closed to the complete apprehension of consciousness.
Consciousness is closed off by the same epistemic boundaries that forbid us from ever
knowing what bat echolocation feels like and that limits blind people from the concept of
sight: "our concepts of consciousness just are inherently constrained by our own form of
consciousness, so that any theory the understanding
these constraints
would
ipso facto be inaccessible to us" {McGinn 1991, 9). Consciousness is
only accessible through introspection,
function.
of which required us to transcend
but introspection
can tell us nothing about brain
Perceptive analysis, on the other hand, can access brain function
consciousness. Since there is no intermediate
but not
method to speak of, Pon the whole is
unexplaninable.
That is not to say P does not exist, however.
NM is not substance dualism;
materialism holds but it simply cannot account for consciousness.
not entail nonexistence.
Cognitive
closure does
Perhaps "Martians or demigods might have better luck"
27
I'm sure such a description is possible. It would sound ridiculous, but it is surely possible.
But in the end, verbal descriptions are understood fully only by the utterer (see figure 2 in
the second chapter of this paper).
51
understanding P, as Dennett writes in his criticism (Dennett
1991b). Something explains the
phenomenon of consciousness, but we can't grasp it. There
is still much to learn from the
study of consciousness, and neuroscience might bring us closer to solving the mind-body
problem than ever before, but the hopes for a unified theory of consciousness
are slim to
none.
CRITICISM AND RESPONSE
Criticism for McGinn's work is far reaching.
Opponents tend to boil down cognitive
closure to a simple syllogism:
Pl.
P2.
P3.
Cl:
Introspection alone cannot fully explain P
External perception of the brain cannot fully explain P
Appeals to inference do not hold because of homogeneity constraints
Therefore, Pis humanly unexplainable by any extant means of
apprehension
C2: P can only be apprehended from a "God's-eye point of view" (Flanagan
1992)
Pl is uncontroversially
true.
My own first-person experience tells me nothing about
neurons or synapses or anything else relevant to a unified theory of consciousness.
If I
never learned that there is lumpy gray matter inside my head, I would have no reason to
ever assume that there is!28 P2 is the problem. McGinn is frequently condemned
defeatist or even Luddite, accusing him of discounting
technology and knowledge.
Simply because a solution
the rapid progression
as
of human
has not yet been found, "the
solution may be just around the corner" (McGinn 1997b, 108). Continued research in
cognitive science and related fields will eventually solve the mind-body problem
28
The point about not knowing about the brain is borrowed from Flanagan
52
and
1992.
provide us with a unified theory of consciousness, allowing us to create sentient
may or may not enslave humanity.
attempts to make.
robots that
In response, such criticism clearly misses the point NM
McGinn's contention
is that the mind-body problem will never be solved
for sure because there is no definitive way of knowing if the solution is in fact correct. There
is no test comprehensive
Furthermore,
enough to test for true sentience, only observable
behavior.
some argue that the truth or falsity of P2 depends on interpretation.
By McGinn's lights, P2 is unequivocally true because direct observation of a brain indeed
tells us nothing about conscious experience.
controversial because the "'unobservability'
On the other hand, the premise is
of the link between P and consciousness
prevents us from inferring that Pis in fact where the link resides" (Flanagan 1992, 112).
is invoked in this point; Flanagan calls into question why inference from unobservable
is insufficient for a theory of consciousness.
P3
data
McGinn invokes Nagel's claim that "it will
never be legitimate to infer, as a theoretical explanation of physical phenomena
alone, a
property that includes or implies the consciousness of its subject" because consciousness
and observable brain states are intrinsically different properties that cannot be used to
explain each other (Nagel 1979, 183).
To Flanagan, however, neural correlation
is sufficient for a complete
explanation:
We are not looking for an explanation of 'physical phenomena alone', at least
not physical phenomena narrowly understood. There is a prior commitment
to the existence of consciousness. Thus both brain facts and facts about
consciousness are on the table to be explained. We then infer that the
constellation of a certain set of phenomenological reports of restricted range
('tastes sweet') correlate with certain sorts of brain activity (activation in the
relevant pathways), and we infer, given an overall commitment to
naturalism, that the latter explains the former. [Flanagan 1992, 113)
53
What makes consciousness so exceptional that the rules of inference
used for electrons,
genes, etc. no longer apply? Electrons, for example, are never actually observed in
experiments that invoke them (i.e. cloud chambers), but we postulate their existence
because other observable data rides on their existence. Similarly, we don't see
consciousness during brain experiments
but consciousness is postulated because the
evidence derived from observed brain activity and overt behavior are incoherent
without
the existence of consciousness. Therefore, Pis explanable through inference.
Flanagan fails to account for what I call the behavior barrier. The behavior barrier is
an updated appeal to the classical philosophical dilemma of other minds combined
Chalmers' argument for the logical possibility of p-zombies.
with
How can we be certain that
something that behaves as if it is conscious is actually in posession of any sort of
phenomenal experience?
While arguments for NM and cognitive closure are admittedly
inductive, postulating the existence of an inner life is inductive as well.
Neural correlation
studies show that the subject is probably in some conscious state, but the only real proof
the experimenters
have is an analogy to their own experience.
Researcher Brown knows he
is a conscious, sentient agent because he can introspect, the same way everybody else
knows that they are not mindless automata.
of introspection
Test subjects Black and Gray are also capable
as well and is thus conscious. Black and Grey are hooked up to a device
that provides a thorough analysis of all brain activity. The device is small
to not cause nervousness or discomfort and distort test results.
and uninvasive,
as
Brown injects a dose of the
little known chemical 11 that causes them both to scream in agony that the area of injection
feels like its on fire. Brown correlates the neural scan data and the subjects'
54
behavior in
order to postulate that chemical 11 causes a painful and localized burning feeling, and this
feeling is concurrent with certain brain patterns.
Is this test conclusive?
As Chalmers 1996 and 2002b show, there is a logical possibility for the existence of
p-zombies who feel nothing at all, but are compositionally
equivalent
to humans who do
feel a burning sensation from chemical 11. Black and Gray show equivalent
neural and
behavioral activity during the test, but while Black feels burning pain, Gray feels nothing at
all because he is a cybernetic organism (cyborg) functionally
humans but entirely devoid of phenomenal experience.
and behaviorally equivalent to
What's most interesting
that Dr. Brown will never know this revealing fact. Gray is so ingeniously
is the fact
designed that he is
capable of passing the even the most trying Turing test questions because he is
programmed with a full life's worth of memories and emotional response behavior.
Indeed,
Gray is unaware that he is a cyborg because he is not actually aware of anything at all. If
Brown is somehow compelled to ask whether Gray is a cyborg, Gray's behavioral
software is
programmed to brush off such questions as ridiculous, just as any other human would do.
My point is that even if the world's foremost neuroscientists
claim to find a unified
theory of consciousness P, there is no definitive way to test its veracity. When I asked
about possibility of the ascription of consciousness onto an artifact, Dreyfus told me:
Once you've got to the point where you have a theory of consciousness and
you're implementing it and its behaving just like human being, then whether
its actually conscious or not will have exactly the same structure as whether
you are actually conscious or not when I'm dealing with you. If that can't be
settled, then maybe it's a p-zombie. [Dreyfus 2011]
His point agrees with mine; the explanatory gap remains indefinitely
unclosed because it is
impossible to "climb in" to someone else's consciousness and find out for sure.
55
In the film
Being John Malkovich, Schwartz, the protagonist, discovers a secret portal that can
transport him into the mind of actor John Malkovich, allowing him to simultaneously
experience Malkovich's inner world as well as his own. Schwartz exclaims,
"Do you know
what a metaphysical can of worms this portal is?" and rightly so; he transcended
idea of first-personality.
the very
But unless a real-life Schwartz really manages to discover such a
portal, the minds of others are indefinitely inaccessible and can never be confirmed
for sure
because of the behavior barrier.
Al, CONSCIOUSNESS, AND BLADE RUNNER: TYING EVERYTHING TOGETHER
If McGinn is right, humanity is cognitively closed to the full understanding
of
consciousness. If a unified theory of consciousness is ever proposed, its truth can only be
postulated but never known for sure. Strong Al proponents disagree. As I discussed earlier,
some theorists believe that the brain is wetware, a biological digital computer.
hardware and the mind is the software it implements,
personal computer.
The brain is
not unlike a video game running on a
And also like a video game, conscious experience is an illusion
by the physical processes "behind the scenes." Computationalists
(or functionalists,
like) claim that conscious states are just functional states of the brain and "feelings
conscious awareness are evoked merely by the carrying out of appropriate
(Penrose 1994). It follows that a complete understanding
caused
if you'd
of
computations"
of how the brain physically works
will eventually give rise to an explanation of consciousness.
In this section I will demonstrate
that like physicalism, a computational
explanation
of consciousness fails to close the explanatory gap and solve the hard problem for sure
56
because of the behavior barrier. Through introspection we can access consciousness
directly, but only through physical experimentation
can we understand
the physical
processes. Unification is futile, and CTM can bring us no closer to an answer
than anything
else.
In order to advance my argument, I will elaborate on themes from Phillip K. Dick's
classic novel Do Androids Dream of Electric Sheep and its film adaptation,
Ridley Scott's
Blade Runner. Both texts have deep philosophical implications ranging from the meaning of
love to the ethics of animal treatment, but I will be primarily focusing on its treatment of
the metaphysical issue of person hood in order to strengthen my argument for the
untenability of solving the hard problem.
The book and the film have similar themes and the same backstory, but significant
variations in plot development.29 Both stories take place in the not-so-distant future in a
dystopian, pollution-riddled Los Angeles. World War Terminus decimated
the human
population and the vast majority of animals are extinct. As a result, empathy towards
animals is revered to an almost religious level and owning a real animal (as opposed to the
more common synthetic replacements) is the highest symbol of status."
The turmoil on
Earth caused the colonization of nearby planets, and the arduous job of construction and
development was assigned to anthropomorphic robots called replicants. Because they are
dangerous to humans, replicants are outlawed on Earth. Protagonist Rick Deckard is a blade
29
For the sake of clarity and continuity, I will use names and terminology from the film
instead of the book. It should be noted that the lifelike Al characters in the film are called
'replicants' while the novel calls them 'androids'. The two terms refer to the same
conceptual construction.
30
The theme of animal ownership and its social implications is a main theme in the novel
but less so in the film. Needless to say, empathy towards animals is crucial to both texts.
57
runner, a bounty hunter who specializes in the "retirement"
of replicants.
around Deckard's hunt for Pris, Zhora, Leon, and Roy, advanced
The plot revolves
Nexus-6 class replicants
who returned to Earth in order to pressure their creator Tyrell to extend their four-year
limited lifespan.
What gives blade runners the right to kill? Replicants
seem to feel
pains and emotions just like their human creators. Among the most
disturbing scenes in the film is when Deckard shoots Zhora, causing her
to fall through multiple panes of glass while she screams and grimaces in
utter agony (Figure 8}. Dick wrote in his essay "Man, Android, and
Figure 8 Warner
Machine" that an android is "a thing somehow generated to deceive us in
a cruel way, to cause us to think it to be one of ourselves" (Dick 1976, 202}. Zhora
seems
human in every way; accordingly so, watching her die so brutally evokes empathy from the
audience. But does she actually feel anything at all, or just
her programming?
behave as if she does because of
Lets assume that replicant "minds" are syntactical computers running
advanced software that causes their overt and physiological behavior to function identically
to humans, "capable of selecting within a field of two trillion constituents, or ten million
separate neural pathways" (Dick 1968, 28}.31
Lets also assume that a computer
mind is not
a mind at all, and no conscious experience arises from it. In this case, replicants are be pzombies, "identical...functiona//y
... reacting in a similar way to inputs ... with indistinguishable
behavior resulting" (Chalmers 1996, 95}. Moreover, they are not conscious,
and have no experience in the same sense that you and I have experience
31
feel no qualia,
of the world.
This entails that Kurzweil's prediction that a comprehensive computational
human brain function is true in 2019 Los Angeles.
58
model of
As
Brothers
Daniel Robinson points out "It is conceivable that a device
could be made in such a way as
to change its appearance and make loud sounds when one or another
component is
destroyed. [ ... ] Here, then, we have a device that replaces 'pain behavior'
with 'pain
language.' We have, in a word, everything but pain!" Behavior, despite
its apparent
authenticity,
is not sufficient for confirmed consciousness.
In this case,there
like to be a replicant, "Chitinous reflex-machines who aren't really alive"
is nothing it is
(Dick 1968, 194).
Regardless, it is natural to feel bad about Zhora's painful and unceremonious
execution.
Accordingly, a central theme in Blade Runner is uncertainty.
litmus test for replicancy/humanity
The only reliable
is the Voight-Kampff (V-K) test that measures
physiological responses to emotionally jarring questions.
Most questions
are about animal
mutilation, a topic that every human cares about deeply; although some replicants
"had
been equipped with an intelligence greater than that of many human beings," they
"possessed no regard for animals ... [and] no ability to feel empathic joy for another life
form's success or grief at its own defeat (Dick 1968, 32). Rachael is a replicant but, unlike
the others, she had real human memories implanted into her neural
"believes" that she is a real human and acts convincingly
not) is up to interpretation.32
Most importantly,
32
network.
so. Even Deckard's
there is a patent uncertainty
She
humanity (or
about
"An android," [Deckard] said, "doesn't care what happens to another android. That's one
of the indications we look for."
'Then," Miss Luft [Zhora's novel analogue] said, "you must be an android." She then asks
whether or not Deckard has taken the V-K test himself.
"Yes." He nodded. "A long, long time ago; when I first started with the department."
"Maybe that's a false memory. Don't androids sometime go around with false memories?"
(Dick 1968, 101-102).
59
mistakenly retiring "authentic
humans with underdeveloped empathic
ability" who fail the
V-K test (Dick 1968, 54).
The V-K test is a reimagined variation on the Turing test.
Remember
that a
computer that passes Turing's imitation game by behaving as a human would is, on some
views, intelligent and conscious. Anti-computationalists like Searle and Dreyfus disagree:
"I'm not enough of a behaviorist to think that if it just behaves like people it shows that it's
intelligent"
(Dreyfus 2011). I agree, to an extent. As Searle made clear in the Chinese Room
argument, simulation is not, in and of itself, proof of duplication.
that an artifact simulates
Judging solely on the basis
consciousness behavior is insufficient evidence for knowing
whether or not it has an inner life at all.
Strangely enough, Dennett, a staunch opponent of Searle's claims,
seems to agree.
A simulation of a hurricane, for instance, is hardly equivalent to a real one. A
comprehensive theory of hurricane behavior can be implemented
simulation.
through a computer
Certain measurable inputs (i.e. barometric and temperature
appropriate outputs (i.e. 150 mph winds blowing westward accompanied
but one should "not expect to get wet or windblown
data) yield
by heavy rain),
in its presence" (Dennett 1981, 191).
By the same lights, an Al can simulate consciousness but be just as lifeless as hurricane
software.
Android S might respond to an anvil dropped on its foot as follows:
S's (-fibers are stimulated, ... a pain memory is laid down; S's attention is
distracted; S's heart-rate increases .. ; S jumps about on right foot, a tear in
the eye, screaming. [Dennett 1981, 192]
S certainly passes the Turing test for pain. Zhora does too. In the novel, replicant Pris acts
like the timid and scared young woman she is meant to resemble:
60
"Fear made her seem ill;
it distorted her body lines, made her appear as if someone had broken her and then, with
malice, patched her together badly" (Dick 1968, 62). Behavior may be convincing but it is
not definitive proof for the existence of mental states.
Roy and his Nexus-6 brethren are programmed with a bottom-up
response mechanism.
Like humans, they are "born" with no emotional
develop them naturally through experience.33
emotional
attachments
but
Dreyfus writes:
Generally, in acquiring a skill - in learning to drive, dance, or pronounce a
foreign, for example - at first we must slowly, awkwardly, and consciously
follow the rules. But then there comes a moment when we finally can
perform automatically. At this point, we do not seem to be simply dropping
these same rigid rules into unconsciousness; rather we seem to have picked
up the muscular gestalt which gives our behavior a new flexibility and
smoothness. [Dreyfus 1994, 248-249]
Emotions are no different.
We gradually learn through experience how to identify specific
emotions and behave appropriately.
Unlike humans, however, the Nexus-6s only have four
years to learn a lifetime of emotions, and there is a clear discrepancy
between their
emotional immaturity and superhuman strength and/or intelligence.
Towards the end of
the film, Roy is distraught to find the lifeless and bloodied
body of his lover Pris, killed by
the blade runner in an earlier scene. His underdeveloped
emotions become evident when
he begins to act oddly, smearing her blood on his lips and howling like a wounded animal.
Earlier on he attempts to inform Pris about the deaths of their allies Leon and Zhora, but his
inability to process emotional depth leads him to convulse and stiffen robotically,
inhumanly.
33
The imbalance of Roy's physical prowess and calculating
Excluding Rachael, who has emotions from her implanted
61
memories.
rationality
with his
emotional handicaps stands in stark contrast with Tyrell Corporation's motto "More human
than human," reminding the audience that replicants are fundamentally
On the other hand, the penultimate
a climactic cat-and-mouse
different than us.
scene adds to the complexity of this issue. After
chase between Deckard and the physically superior Roy, Deckard
finds himself facing his death, clinging to a roof beam for dear life. In a beautiful display of
what appears to be humanity, Roy chooses to save Deckard. Throughout the film, Roy is
obsessed with extending his limited lifespan but in the end, he finally seems to understand
the value and transience of life:
Rov: I've seen things you people wouldn't believe. Attack ships on fire off the
shoulder of Orion. I watched C-beams glitter in the darkness at Tannhai..iser
Gate. All those moments will be lost in time like tears in rain. [Fancher and
Peoples 1982]
Deckard can only sit back in awe as his savior perishes. It certainly appears that Roy
feels something, judging by his actions. In his essay on postmodernism in Blade
Runner, Nick Lacey writes, "In [Roy's] final moments, when he saves Deckard, he
becomes human because of his behavior and his realisation that his life was worth
living (Lacey 2005, 190}. Marilyn Gwaltney adds that movie audiences
with Roy because, "Our understanding
sympathize
of his cruelty changes as we come to
understand it as a very human reaction to his existential situation: the imminence of
his death and that of those he loves; the feeling of betrayal by the beings that
brought him into existence" (Gwaltney 1997, 33}. But can we safely assume that this
sort of demonstrated
self-realization
implies phenomenal first-person experience?
Gwaltney later writes, "Computers may be thought to act rationally,
in the sense of
acting logically, but they do not act to any purpose of their own, only to the purposes of
62
others. To act with purpose requires consciousness of self"
(Gwaltney 1997, 35).
Roy
certainly appears conscious and self-aware, but in the end, he could very well still be a pzombie. If technology in the Blade Runner universe is advanced enough
Nexus-6, software for this sort of humanlike behavior is surely plausible.
to create the
It thus follows that
Roy's epiphany, despite its personal impact, might not feel like anything at all to him.
This is
a hard concept to swallow, considering how dramatic an effect it appears to have. Indeed,
actor Rutger Hauer completely improvised the "tears in rain" speech,
own felt experiences.
no doubt drawn his
But if the assumption that replicants are p-zombies is correct, Roy
feels nothing at all while his artificial brain implements the program
SELF _REALIZATION_EPIPHANY.EXE
in the background, no different from my laptop not feeling the
word processer currently running. As Rachael laments in the novel, "We are machines,
stamped out like bottle caps. It's an illusion that 1-1 personallyrepresentative
of a type ... I'm not alive." (Dick 1968, 189, 198}.
But remember, none of this can be definitively
otherwise.
really exist; I'm just
proven by any test, Turing, V-K, or
Both claims in support and against machine consciousness
reasoning that cannot be verified for sure. On the possibility
are based on
of a conscious artifact of
human creation, McGinn contends, "I should say the matter is entirely
an empirical one: it
concerns whether human beings ever in fact achieve enough in the way of scientific and
technological knowledge" to close the explanatory gap and physically observe the existence
of conscious experience.
"It is like asking whether we shall ever travel to another galaxy"
(McGinn 1991, 203}. Since replicants are human creations, as of now it is an empirical
impossibility of ever confirming if it there is anything it is like to be one. On the other hand,
63
the possibility of a conscious artifact
in general is a matter of principle.
If hyper intelligent
Martians (the philosophers' favorite species) were to abduct a human and reproduce it
molecule for molecule, there is no reason to say the clone isn't conscious. Of course, it may
very well be a p-zombie, devoid of any experience at all, but only Martians who understand
the explanatory gap can know for sure. Whether or not replicants are anything more than
lifeless "skinjobs," as they are disparagingly called, is ultimately beyond our epistemic
boundaries.
Figure 9 Dilbert.com
64
CONCLUSION
In this work I make the claim that sentient artificial intelligence may be possible, but
it is beyond the epistemic limits of human understanding
to ever devise a test
comprehensive enough to prove it for sure. Neither functionalism
and CTM nor physical ism
account for the explanatory gap dividing first-person conscious experience
and externally
observable neural and behavioral correlates.
accessible to an
Mental states are exclusively
individual mind and any attempts to describe them verbally
are limited
by ostensive
definition and the boundaries of natural language. There is no conceivable means of
knowing whether or not 'sadness' feels the same to me as it does to you; observable
behavior can be simulated but not conclusively duplicated.
only assess behavioral equivalence.
Accordingly, the Turing test can
As we see in Blade Runner, simply because something
looks and acts sentient does not necessarily entail sentience.
mysterians about consciousness.
I contend that we should be
Neuroscience and related fields continue to make
remarkable progress in the study of both consciousness and Al and should certainly
continue to do so. However, it is beyond the cognitive capacity
fully explain consciousness in a testable and provable theory.
for human
beings to ever
If Terminator is an accurate
prediction of the future, whether or not Skynet is sentient is forever unknown.
65
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