Hume recap - Jason Grossman

Contents (this week and next week)
EMPIRICISM
PHIL3072, ANU, 2015
Jason Grossman
http://empiricism.xeny.net
Recap
Hume's fork
Logical positivism: a very brief ahistorical introduction
Bertrand Russell: reductionism in mathematics and logic
More on logic and (if time) principles of rationality
Bertrand Russell: empiricism and logical atomism
lecture 7: 25 August
Hume's fork
Betrand Russell and reductionism
Hume recap
This week and next week:
Everyone gets to introduce a question or a small topic to discuss.
Recap — Hume's methodology
“Let us x our attention out of ourselves as much as possible; let us
chace our imagination to the heavens, or to the utmost limits of the
universe; we never really advance a step beyond ourselves, nor can
conceive any kind of existence, but those perceptions, which have
appear'd in that narrow compass. This is the universe of the
imagination, nor have we any idea but what is there produced.”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, , 1.2.6.
Recall that Locke's radical empiricism wanted the mind to start as a
tabula rasa, which caused him problems.
In contrast, Hume comes down on the side of built-in principles by
which the mind functions
following scientists' (especially Newton's) success in nding
underlying regularities, e.g. the equations of gravity.
Recap — Impressions and ideas
Hume's perceptions = Locke's ideas. Hume subdivides perceptions
into impressions and ideas.
Hume's impressions are feelings (roughly Berkeley's ideas):
sensations and passions (desires and emotions)
Hume's ideas are thoughts: “the faint images of [impressions]
in thinking and reasoning”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.1.1.1.
Note the importance of introspection.
Why is introspection particularly important to empiricists?
What will empiricists do when introspection goes out of
fashion? (Guess!)
“Simple perceptions or impressions and ideas are such as admit of no
distinction nor separation.”
These will later become Russell's logical atoms.
— Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.1.1 (my emphasis)
Recap — The copy principle
“all our simple ideas in their rst appearance are deriv'd from simple
impressions, which are correspondent to them, and which they exactly
represent.”
Roughly, simple thoughts are produced (at rst) by simple
sensations.
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.1.1 (his emphasis)
Hume believes the copy principle is important because it subsumes the
whole debate about innateness: people (Locke etc.) have shown that
ideas are not innate by showing that they are preceded by impressions,
which they copy and combine.
Recap — Why is causation special?
Hume's copy principle only applies to simple ideas (unlike Locke's).
How do we get complex ideas?
Typically in 3 ways:
resemblance
contiguity in time or place
cause and effect
but this is just an observation, not a rule.
Recap — Why is necessary connection special?
Hume's priority (unlike Berkeley's) is to decide between de nite
knowledge of causation and mere belief.
He argues for mere belief.
Hume says his goal is to show that causation is not necessary
connection.
The point of that is that if causation is not necessary then we can't have
deductive (“demonstrative”) knowledge of it
so it must be a relation between ideas.
Note the empiricism, and the lack of dogmatism.
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.1.4
Of these, causation is special because
“of those three relations . . . the only one, that can be traced
beyond our senses and informs us of existences and objects,
which we do not see or feel, is causation”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.3.2
Recap — Hume's argument against using induction to demonstrate causes
Recap — Hume's argument against using induction to demonstrate caus
“It may, perhaps, be said, that after experience of the constant
conjunction of certain objects, we reason in the following manner. Such
an object is always found to produce another. 'Tis impossible it cou'd
have this effect, if it was not endow'd with a power of production.
The [causal] power necessarily implies the effect; and therefore there is
a just foundation for drawing a conclusion from the existence of one
object to that of its usual attendant.
The past production implies a [causal] power: The [causal] power
implies a new production: And the new production is what we infer
from the [causal] power and the past production.”
Hume disposes of this argument with his famous argument on induction
(sort of).
“But it having been already prov'd, that the [causal] power lies not in
the sensible qualities of the cause; and there being nothing but the
sensible qualities present to us; I ask, why in other instances you
presume that the same [causal] power still exists, merely upon the
appearance of these qualities? Your appeal to past experience decides
nothing in the present case; and at the utmost can only prove, that that
very object, which produc'd any other, was at that very instant endow'd
with such a [causal] power; but can never prove, that the same [causal]
power must continue in the same object or collection of sensible
qualities; much less, that a like [causal] power is always conjoin'd with
like sensible qualities.
Shou'd it be said, that we have experience, that the same [causal]
power continues united with the same object, and that like objects are
endow'd with like [causal] powers, I wou'd renew my question, why
from this experience we form any conclusion beyond those past
instances, of which we have had experience. If you answer this
question in the same manner as the preceding, your answer gives still
occasion to a new question of the same kind, even in in nitum”
“Hume's problem of induction”
causation
conclusions
Note that Hume's conclusion here is that using induction to assign
necessary connection to causal powers is circular.
“Hume's problem of induction” is usually used to refer to the conclusion
that using induction to justify induction is circular.
Not the same conclusion at all! But essentially the same argument works
for both.
“Hume's problem” of the justi cation of induction is not actually found
anywhere in Hume. (But it is found in plenty of other places,
e.g. Sextus Empiricus — see rationalism lecture notes.)
What IS causation then?
“A Treatise of HUMAN Nature”?
Since causation is not a necessary connection, but since nevertheless it's
a concept we use, it must be a mere custom or habit.
“men are not astonish'd at the operations of their own reason, at the
same time, that they admire the instinct of animals, and nd a dif culty
in explaining it”*
And the tendency of people to have this habit is unexplained.
This illustrates the sense in which Hume's theory is a theory of “human
nature”.
(Hume named his main work “A Treatise of Human Nature”,
but see below.)
“To consider the matter aright, reason is nothing but a wonderful and
unintelligible instinct”
“This instinct, 'tis true, arises from past observation and experience; but
can any one give the ultimate reason, why past experience and
observation produces such an effect . . . ? . . . Nay, habit is nothing but
one of the principles of nature”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 1.3.16
Hume's fork
Hume's fork: Treatise version, 1739
“Truth or falshood consists in an agreement or disagreement either to
the real relations of ideas, or to real existence and matter of fact.
Whatever, therefore, is not susceptible of this agreement or
disagreement, is incapable of being true or false, and can never be an
object of our reason.”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, 3.1.1
As used in his analysis of causation:
“real relations of ideas” = “understanding” and “reason” =
mathematics or logic
“real existence and matters of fact” = “association . . . of
perceptions” = empirical facts
Hume's fork: Enquiries version, 1748
“All the objects of human reason or enquiry may naturally be divided
into two kinds, to wit, Relations of Ideas, and Matters of Fact.
Of the rst kind are the sciences of Geometry, Algebra, and Arithmetic;
and in short, every af rmation which is either intuitively or
demonstratively certain.
That the square of the hypothenuse is equal to the square of the two
sides, is a proposition which expresses a relation between these gures.
That three times ve is equal to the half of thirty, expresses a relation
between these numbers. Propositions of this kind are discoverable by
the mere operation of thought, without dependence on what is
anywhere existent in the universe. Though there never were a circle or
triangle in nature, the truths demonstrated by Euclid would for ever
retain their certainty and evidence.”
Hume's fork: Enquiries version
“Matters of fact, which are the second objects of human reason, are not
ascertained in the same manner; nor is our evidence of their truth,
however great, of a like nature with the foregoing.
The contrary of every matter of fact is still possible; because it can never
imply a contradiction, and is conceived by the mind with the same
facility and distinctness, as if ever so conformable to reality.
That the sun will not rise to-morrow is no less intelligible a proposition,
and implies no more contradiction than the af rmation, that it will rise.
We should in vain, therefore, attempt to demonstrate its falsehood.
Were it demonstratively false, it would imply a contradiction, and could
never be distinctly conceived by the mind.”
— David Hume,
An Enquiry Concerning Human Understanding, Part I, 1748/1909–14. The Harvard Classics, http://www.bartleby.com/37/3/4.html, viewed
12/2/2008
— David Hume,
An Enquiry Concerning Human Understanding, Part I, 1748/1909–14. The Harvard Classics, http://www.bartleby.com/37/3/4.html, viewed
12/2/2008
But recall that Hume was very tight about what counted as
“demonstratively certain”, so . . .
Hume's fork: Enquiries version, conclusion
“When we run over libraries, persuaded of these principles, what havoc
must we make? If we take in our hand any volume; of divinity or school
metaphysics, for instance; let us ask,
Does it contain any abstract reasoning concerning quantity or
number?
No.
Does it contain any experimental reasoning concerning matter
of fact and existence?
Empiricist terminology
Subsequent empiricists mostly follow Hume's de nition of
“metaphysics”, especially later empiricists.
Logical positivism, especially, is a detailed attempt to do without
metaphysics in this sense . . .
But some later philosophers (e.g. Huw Price) use a much broader
de nition, so they can agree with Hume's empiricism but still think of
themselves as doing metaphysics.
This is why I mostly talk about “ontology” rather than “metaphysics”.
No.
Commit it then to the ames: for it can contain nothing but
sophistry and illusion.”
— David Hume, An
Enquiry Concerning Human Understanding, Part III, 1748/1909–14. The Harvard Classics, http://www.bartleby.com/37/3/19.html, viewed
12/2/2008
This is often taken as a repudiation of metaphysics, but Hume
speci cally restricts his criticism to “school metaphysics”, i.e. the roughly
Aristotelian Scholasticism still being taught in the universities at the time.
And . . .
Hume's fork: my conclusion
“When we run over libraries, persuaded of these principles, what havoc
must we make? If we take in our hand any volume; of divinity or school
metaphysics, for instance; let us ask,
Does it contain any abstract reasoning concerning quantity or
number?
No.
Does it contain any experimental reasoning concerning matter
of fact and existence?
No.
Hume's opposition to metaphysics — a problem?
“Let us x our attention out of ourselves as much as possible; let us
chace our imagination to the heavens, or to the utmost limits of the
universe; we never really advance a step beyond ourselves, nor can
conceive any kind of existence, but those perceptions, which have
appear'd in that narrow compass. This is the universe of the
imagination, nor have we any idea but what is there produced.”
— David Hume, “A Treatise of Human Nature”, http://www.davidhume.org/texts/thn.html, viewed 2015-08-01, , 1.2.6.
How is Hume's opposition to “metaphysics” compatible with Hume's
opposition to the tabula rasa theory of radical empirisism?
To avoid the tabula rasa, doesn't he need rationalist principles?
Commit it then to the ames: for it can contain nothing but
sophistry and illusion.”
Hume exempts logic from radical empiricism because he agrees with my
(type of) argument about needing principles of rationality
but he gives no argument for why principles of rationality are restricted
to “quantity and number”
or for why there should be no other exceptions to radical empiricism
but he does discuss how he thinks ethics can be empiricist.
Hume's opposition to metaphysics — a problem?
How is Hume's opposition to “metaphysics” compatible with Hume's
opposition to the tabula rasa theory of radical empirisism?
To avoid the tabula rasa, doesn't he need rationalist principles?
This is Hume's great (and original?) contribution to empiricism:
We can't know what is outside ourselves
which means we can't know what produces the regularities that
form our nature (e.g. principles of rationality)
but we can talk about these regularities anyway, exactly as
we can talk about the regularities in Newton's physics.
So Hume has principles which are effectively a priori but which we
infer only tentatively through our observations.
Michael Friedman calls this (retrospectively) the relativized a priori.
Yes, this is very similar to Kant's synthetic a priori. (Differences?)
Hume's relativized a priori had a very direct in uence on 20th-century
scientists and on the logical positivists.
.
logical positivism
What is logical positivism?
A philosophical movement co-founded by a number of people with
different views.
sort of (precursors): Ernst Mach, Albert Einstein, Bertrand
Russell, Ludwig Wittgenstein
de nitely: (Vienna Circle:) Hans Hahn, Otto Neurath, Philipp
Frank, Moritz Schlick, Rudolf Carnap, Kurt G•
odel, Herbert
Feigl, Richard von Mises, Karl Menger, Friedrich Waismann,
Felix Kaufmann, Viktor Kraft, Edgar Zilsel, Gustav Bergmann,
Olga Hahn-Neurath, Bela Juhos, Felix Kaufmann, Victor Kraft,
Karl Menger, Rose Rand, Josef Sch•achter, Edgar Zilsel;
(Berlin Circle:) Hans Reichenbach, Kurt Grelling, Walter
Dubislav, Carl Hempel, David Hilbert, Richard von Mises;
(Oxford:) A. J. Ayer.
sort of: Willard van Orman Quine
Relationship to the cutting edge of science
The rise of empiricism among scientists came after early modern science
but before 20th century science:
1687: Newton's Principia (action at a distance)
1739–1748: Hume
19th century: Mach and other Humeans;
Poincare's empiricist conventionalism
1905: Einstein's very empiricist Special Relativity, and his early
contributions to quantum theory
1911–1924: Russell's logical atomism
— First appearance of logical atomism: “Le Réalisme analytique” (1911), translated as “Analytic Realism,” in Collected Papers of Bertrand
Russell, vol. 6, Logical and Philosophical Papers, 1909–1913, ed. J. G. Slater. London: Allen & Unwin, 1992, pp. 133–46
1915: Einstein's General Relativity
1921: Wittgenstein's logical atomism (Tractatus Logico-Philosophicus)
Also called logical empiricism.
1925–1932: Quantum mechanics
An attempt to combine empiricism (roughly, Hume's) with 20th century
science . . . but . . .
1928–1936: The Vienna Circle and the Berlin Circle
Positivist doctrines
1. We should not do metaphysics.
But what is metaphysics?
For positivists (following Hume), it's anything which is not based on
either:
experience, or
Positivist doctrines
3. veri cationism: The meaning of a (scienti c) statement consists of
the difference it makes to our experiences.
But:
“The number of stars in the Andromeda galaxy is prime.”
“The last Tyrannosaurus to die had a cute nose.”
logic.
Logic was greatly expanded though; Carnap even included
inductive logic.
These sentences are meaningful, but they don't make any difference to
our experiences.
(This list of doctrines is from Anthony O'Hear, An Introduction to the
Philosophy of Science, Oxford: Oxford University Press, 1989.)
2. “sensory observation founds all genuine knowledge”.
— Anthony O'Hear, An Introduction to the Philosophy of Science, Oxford: Oxford University Press, 1989, p. 107
Positivist doctrines
3. veri cationism: The meaning of a (scienti c) statement consists of
the difference it makes to our experiences.
Weaker (and therefore more useful) forms of veri cationism:
“the meaning of a term is given by the circumstances which would verify
its application”
— David Braddon-Mitchell and Frank Jackson, “Philosophy of Mind and Cognition”, Malden: Blackwell, 2007, p. 309
Positivist doctrines
4. Laws of nature are just our preferred way of describing regularities.
Possible counter-claim: The success of science suggests that our laws of
nature are a particularly good way of describing regularities.
I don't know any way to make that counter-claim precise.
(And the logical positivists didn't like it anyway.)
or
“the meaning of a sentence is the method you should use to determine
if it is true”
— David Braddon-Mitchell and Frank Jackson, “Philosophy of Mind and Cognition”, Malden: Blackwell, 2007, p. 43
or
The meaning of a statement is given by our grasp on what it would take
to verify it in principle.
The logical positivists generally moved from the strict form of
veri cationism to a weaker form, and then gave up on veri cationism
altogether but kept their other doctrines.
5. Since laws of nature are not fundamental, nor are explanations.
This doesn't mean that our explanations are wrong, or that any
explanation will do.
Maybe our explanations are likely to be right,
whereas many other possible explanations are worse.
The suggestion is that there is more than one explanation of
anything, and no fundamental way to choose between them.
Positivist doctrines
6. The existence or non-existence of unobservable entities
doesn't matter, although we should still use unobservable entities in
our theories whenever we nd them helpful.
This follows from the previous doctrine.
This is a type of quietism.
Popularised by logical atomism (both Russell's and
Wittgenstein's).
Russell:
reductionism
Recall similar positions with other names:
Arthur Fine (1996) calls it the Natural Ontological Attitude; Stephen
Yablo (1998) calls it the quizzical attitude: “the one that doubts there
is anything to nd” about existence questions “and is inclined to shrug
the question off”.
Russell's life and writing
Important in philosophy from 1903 to 1948. (Lived from 1872 to
1970.)
Brother introduces him to maths when he's 11. Bertie nds the
experience “as dazzling as rst love”.
Australia (1950)
A newspaper wrote that Russell looked like “a sophisticated koala bear
who has just thought of a funny story”.
— Alan Wood, Bertrand Russell, The Passionate Sceptic, p. 212.
Russell went to see a koala and decided it was a compliment.
— Bertrand Russell, The Autobiography of Bertrand Russell, 2nd Edition, London: George Allen and Unwin, 1971 [cited below as
“Autobiography”] Volume 1, p. 11
Goes to Cambridge. Studies maths then philosophy.
“I derived no bene ts from lectures, and I made a vow to myself that
when in due course I became a lecturer I would not suppose that
lecturing did any good. I have kept this vow.”
— Autobiography, Volume 1, p. 67
Imprisoned for 5 months during World War I for writing an article
mentioning the use of the American Army to break strikes.
1916: Fired from Trinity College, Cambridge (eventually re-employed
1945–1950).
Consequently had to write a lot!
— picture: Alan Wood, Bertrand Russell, The Passionate Sceptic, p. 224f.
Also ran a primary school, and worked as a casual lecturer —
toured America 7 times and Australia once.
Russell's various reductionist theories
de nite descriptions: a theory of the word “the”
“Whereas it used to be said that philosophy is about, for example,
Goodness or Existence or Reality or How the Mind Works, or whether
there is a Cat on the Mat, it appears, in retrospect, that that was just a
loose way of talking. Strictly speaking, philosophy consists (or consists
largely, or ought to consist largely) of the analysis of our concepts
and/or of the analysis of the `ordinary language' locutions that we use to
express them.
Still, there was felt to be trouble pretty early on. For one thing, no
concepts ever actually did get analysed, however hard philosophers
tried. (Early in the century there was detectable optimism about the
prospects for analysing `the', but it faded).”
— Jerry Fodor, London Review of Books, Vol. 26 No. 20, 21 October 2004, pages 17-19
logical analysis of language more generally: translation of sentences into
more logical forms
“Principia Mathematica”, 1903 to 1910–1913
The methodology of logical analysis: “The method of `postulating' what
we want has many advantages; they are the same as the advantages of
theft over honest toil.”
— Bertrand Russell, Introduction to Mathematical Philosophy, p. 71
So, instead, de ne what we want.
A lot of major mathematics and philosophy was done along the way
Logicism: “The primary aim of Principia Mathematica was to show that
all pure mathematics follows from purely logical premisses and uses only
concepts de nable in logical terms.”
— Bertrand Russell, My Philosophical Development, London: George Allen and Unwin, 1959, p. 74
“The supreme maxim in scienti c philosophizing is this:
Wherever possible, logical constructions are to be substituted
for inferred entities.”
— Bertrand Russell, “The Relation of Sense-data to Physics”, in “Mysticism and Logic”, London: George Allen & Unwin, 1917; reprinted in
Totowa, New Jersey: Barnes & Noble Books, 1951, pp. 108-131. p. 115
logical atomism: the world is made up of atomic facts (roughly,
sensations) which can be analysed logically
neutral monism: the world is made of stuff which is neither mental nor
physical
Russell's Parodox was bypassed by his new theory of types.
Further reductionism: the Sheffer stroke
The kind of thing that made logical reductionism seem exciting:
p | q is de ned as meaning that p and q are not both true.
¬p
≡
if p then q
p or q
p and q
p|p
≡
≡
≡
p | (q | q)
(the material conditional)
(p | p) | (q | q)
(p | q) | (p | q)
The Sheffer stroke is named after Henry M. Sheffer, but it was invented
by Charles Sanders Peirce around 1880.
“Stigler's Law ... No scienti c discovery is named after its original
discoverer.”
— Stephen M. Stigler, Statistics on the Table, Cambridge MA and London: Harvard UP, 1999, p. 277
Problems with truth functional logic
The problem of the material conditional
The material conditional is the truth-functional version of “if
. . . then”
the extended liar (Epimenides) paradox
despite which Russell's logic is still orthodox in most circles
perhaps because there's no agreement on the best solution to these
problems.