Logical%20Positivism

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Logical Positivism

• Ayer on The A Priori

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Language, Truth and Logic
LOGICAL POSITIVISM

• Ayers report on what the Vienna Circle was
  doing, for English-speaking folk.

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What Im going to do

• The Vienna Circle and its historical antecedents,
  its influence on analytic philosophy
• The Logical Positivist program, including
• The Verification Principle and anti-metaphysical
  agenda
• Philosophy as analysis the quest for an ideal
  language
• Commitment to phenomenalism
• Ayer on the A Priori
• The analytic/synthetic distinction
• Math and logic as tautologous

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Logical Positivism is a form of Empiricism
Thought is an independent source of knowledge.
No! All factual knowledge comes from experience

• It is characteristic of an empiricist to eschew
  metaphysics, on the ground that every factual
  proposition must refer to sense experience.
• Problem how to account for necessary truths,
  including notably truths of mathematics and logic
  since its always possible in principle to
  falsify empirical generalizations.
• Ayer needs an account that will get rid of bad
  metaphysics without throwing out good
  mathematics.

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The Elimination of Metaphysics

• The Metaphysical Thesis philosophy affords us
  knowledge of a reality transcending the world of
  science and common sense.
• The Absolute enters into but is itself incapable
  of evolution and progress. (Bradley)
• Nothing noths (Heidegger)
• Ayers Thesis talk about such a transcendent
  reality is, literally, meaningless.
• The function of philosophy is wholly critical
• Philosophy leaves everything as it is.
• The business of philosophy is analysis the
  propositions of philosophy arelinguistic in
  character.

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Were deluded by language

• E.g. the Fido-Fido theory of meaning every noun
  names an object
• The Winos Paradox
• Nothing is better than champagne
• Thunderbird is better than nothing
• Therefore Thunderbird is better than champagne
• Challenge translate this argument into
  thelanguage of predicate logic!
• Russell showed that the correct analysisof the
  logical form of these claims blocksthe inference.

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Not your grandmothers empiricism!

• The old Kantian attack on metaphysics was
  epistemological
• Starting from experience all we can validly infer
  are further facts about experience.
• But the metaphysician can just claim access
  totranscendent reality via intellectual
  intuition
• Even if intellectual intuition is baloney,
  thisdoesnt show his conclusions are falsejust
  that we cant know whether theyretrue or false.
• Logical positivists hold that metaphysicalclaims
  are neither true nor false but literallymeaningle
  ssi.e. nonsense.

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The Business of Philosophy is Analysis

• Paraphrasing away Russells On Denoting as the
  paradigm of analysis
• Nothing is better than champagne (?x) (x is
  better than champagne)
• Artificial languages as means to accomplish
  analysis
• Logical constructions and inferred entities
• We are all phenomenalists now.
• Analysis is concerned with cognitive content
  understood in terms of equivalence and entailment
  relations.
• Goal the elimination of metaphysics

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Is denying metaphysics is just more metaphysics?

• Wittgenstein says, "in order to draw a limit to
  thinking, we should have to think both sides of
  this limit," a truth to which Bradley gives a
  special twist in maintaining that the man who is
  ready to prove that metaphysics is impossible is
  a brother metaphysician with a rival theory of
  his own.
• So we cant adopt Kants strategy of arguing that
  metaphysics is psychologically impossible since
  that would mean showing that there are
  metaphysical truths that we couldnt
  understandwhich is itself a metaphysical claim
• To avoid just doing more metaphysics we have to
  show that metaphysical claims are meaningless.
• So we adopt the Verification Principle as a
  criterion for meaningfulness.

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The Verification Principle

• To state the circumstances under which a
  proposition is true is the same as stating its
  meaning. (Schlick)
• A sentence is factually significant to any given
  person, if and only if, he knows how to verify
  the proposition which it purports to express.
• Example Theres a skunk living in the crawl
  space under my house.
• I know what experiences would verify the
  proposition this sentence purports to expressfor
  example
• Every few days I experience a characteristic
  smell.
• My dog was barking like crazy, then ran into the
  house yelping and whiningand stinking.
• I saw a black and white animal in my driveway.

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Bad Metaphysics flunks the Verification Test

• Challenge what experiences would verifyor
  falsifythe following metaphysical claims?
• The Absolute enters into but is itself incapable
  of evolution and progress. (Bradley)
• Nothing noths (Heidegger)
• Problem what experiences would verify
• claims about laws of nature
• claims about the past e.g. Lucy had exactlyfour
  children

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Practical Verifiability Verifiability in
Principle

• Propositions about the past cant now be
  conclusively verified or falsified but we can say
  what sorts of experiences would verify or falsify
  them.
• Verifiability doesnt have to be feasible--only
  possible in principle
• There are mountains on the other side of the moon
• Lucy had exactly four children
• We require only verification in principle we
  have to be able to say what sort of experience
  would verify of falsify.
• So propositions about the past are ok.

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Strong and Weak Verification

• A proposition is verifiable in the strong sense
  iff its truth could be conclusively established
  in experience.
• A proposition is verifiable in the weak sense iff
  it is possible to render it probable.
• All we require for meaningfulness is weak
  verifiability
• So laws of nature, which are merely very, very,
  very, very, very highly probable are ok.
• Only a tautology, a claim which has no factual
  content and conveys no information about the
  world, can be anything more than a probable
  hypothesis.
• Example Either today is Tuesday or today is not
  Tuesday.

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Whats hot and whats not

• Sense
• Ordinary empirical claims, e.g. theres a skunk
  living in my crawlspace.
• Claims about remote times and places, e.g. Lucy
  had 4 children.
• Laws of nature, e.g. under conditions found on
  earth, water freezes at 32 F.

• Nonsense
• Metaphysics, e.g. nothing noths.
• Theology, e.g. God exists.
• Ethics, e.g. Torturing young children for fun is
  wrong.
• Aesthetics, e.g. St. Pauls, London, is one of
  the 10 most beautiful buildings in Europe.

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Throwing out the baby with the bathwater?

• The elimination of metaphysics mission
  accomplished.
• Theology as nonsense no problem.
• Ethics (and aesthetics) can be reconstructed as
  expressive or prescriptive.
• But with math and logicwe have a serious
  problem.

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The Empiricists Math Dilemma

• The empiricist must deal with the truths of logic
  and mathematics in one of the two following ways
  he must say either that they are not necessary
  truths, in which case he must account for the
  universal conviction that they are or he must
  say that they have no factual content, and then
  he must explain how a proposition which is empty
  of all factual content can be true and useful and
  surprising.

Not necessary truths!
No factual content!
J. S. Mill
David Hume
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Mills view rejected
2 2 4

• The course of maintaining that the truths of
  logic and mathematics are not necessary or
  certain was adopted by Mill. He maintained that
  these propositions were inductive generalizations
  based on an extremely large number of instances.

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Ayer goes with Humes Fork
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
first kind are the sciences of Geometry, Algebra
and Arithmetic... which are discoverable by the
mere operation of thought ... Matters of fact,
which are the second object 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. Hume, Enquiry
Concerning Human Understanding
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. Commit it then to the flames
for it can contain nothing but sophistry and
illusion. Hume, Enquiry Concerning Human
Understanding
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Language, Truth and Logic

• Metaphilosophy the function of philosophy and
  how it accomplishes its results
• Humes Fork Tautologies and factual claims
• The a priori math and logic
• Factual claims science and everything else
• Nonsense ethics and theology
• (Dis)solutions of traditional philosophical
  problems

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Kant The Analytic/Synthetic Distinction

• In all judgments in which the relation of a
  subject to the predicate is thought this
  relation is possible in two different ways.
  Either the predicate B belongs to the subject A
  as something that is (covertly) contained in this
  concept A or B lies entirely outside the concept
  A In the first case, I call the judgment
  analytic, in the second syntheticI merely draw
  out the predicate in accordance with the
  principle of contradiction, and can thereby at
  the same time become conscious of the necessity
  of the judgment (Kant)
• Analytic sentences are true in virtue of language
  alone
• Theyre a priori (knowable independent of
  experience) because theyre empty of factual
  content.
• Theyre necessary because we dont allow them to
  be false, e.g.
• if the angles of a figure dont add up to 180
  degrees we dont count it as a Euclidean triangle.

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A meaningful sentence is one or the other

• Math and Logic
• analytic true in virtue of language alone.
  Its validity depends solely on the definitions
  of the symbols it contains.
• a priori knowable prior to experience
• necessary not logically possible that they be
  false

• Everything else
• synthetic not analytic. Its validity is
  determined by the facts of experience.
• a posteriori (empirical) can only be known
  after (on the basis of) experience
• contingent not necessary

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Some Hard Questions

• Does anything (respectable) escape Humes Fork?

Water is H20
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The truths of logic and math are analytic

• Objection If all the assertions which
  mathematics puts forward can be derived from one
  another by formal logic, mathematicians cannot
  amount to anything more than an immense
  tautologyCan we really allow that these
  theorems which fill so many books serve no other
  purpose than to say in a roundabout fashion A
  A?

You betcha!
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Tautologous doesnt mean obvious

• The power of logic and mathematics to surprise
  us dependson the limitations of our reason. A
  being whose intellect was infinitely powerful
  would take no interest in logic and mathematics.
• We reject truths of reason which purport to
  establish facts about the world outside of
  language by a priori reasoning.
• And we reject Kants synthetic a priori
• There is a sense in which analytic propositions
  do give us new knowledge. They call attention to
  linguistic usages, of which we might otherwise
  not be conscious and they reveal unsuspected
  implications in our assertions and beliefs.
• The business of philosophy is analysis to elicit
  those features linguistic usage and reveal
  entailment relations.

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A paradigmatic philosophical question

• A bear walks a mile south, a mile east and a
  mile northand ends up where he started. How is
  that possible?
• We know the answer of course
• But how come it only works near the North Pole???

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Its a question about linguistic conventions!

• North and south trace along longitude lines
  which converge at the North and South poles.
• East and west trace along latitude lines
  which are concentric and dont converge

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Who cares what games we choose

• Whether a geometry can be applied to the actual
  physical world or not, is an empirical question
  which falls outside the scope of the geometry
  itself. There is no sense, therefore, in asking
  which of the various geometries known to us are
  false and which are true. In so far as they are
  all free from contradictions, they are all
  trueThe propositions of pure geometry are
  analyticthe reason why they cannot be confuted
  in experience is that they do not make any
  assertion about the empirical world. They simply
  record our determination to use words in a
  certain fashion.

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Summing up

• All factually significant propositions are a
  posteriori (empirical)
• Sentences which purport to be factually
  significant but fail the Verification Principle
  are nonsense.
• A priori propositions are devoid of factual
  content.
• Theyre meaningful only if theyre tautologies,
  i.e. analytic.
• A priori propositions that arent tautologies are
  metaphysical junka result of our
  misunderstanding of language
• Substance comes from our primitive
  superstition that subject-predicate form
  reflects the structure of reality.
• Being comes from the surface grammatical quirk
  that we express existential sentences with is
  which also does the job of predication. Existence
  is not a predicate!

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Some questions

• What is the status of the Verification Principle
  itself?
• Is it an empirical claim made probable by
  experience?
• Is it a tautology true just in virtue of the
  meanings of words?
• Do analytic, a priori, necessary and synthetic,
  empirical, contingent line up neatly in the way
  suggested?
• analytic and synthetic are semantic notions
• a priori and a posteriori concern the way in
  which propositions are known
• necessary and contingent are metaphysical notions
  concerning the conditions with which propositions
  are compatible

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More questions

• Suppose the Verification Principle is a
  methodological prescription has Ayer fiddled it
  to let in what he likes but exclude what he
  doesnt like, i.e. metaphysics and theology?
• Does Ayer have an adequate account of mathematics
  given Gödels proof that in any system rich
  enough to formalize arithmetic there are
  propositions which are true within the system
  that arent derivable within the system?
• Can the distinction between analytic and
  synthetic propositions be made in a
  non-question-begging way?

No!