Willard Van Orman Quine

Quine and Logical Positivism 239
known not on an ultimate basis of sensory experience, in particular
mathematics and logic, is analytic. The result of Carnap’s investigations
was The Logical Syntax of Language. This second attempt to
establish a logical positivism – that is, to use logic to uphold a modified
form of positivism – had been necessitated by the realization
that key axioms of Principia Mathematica could not be defended as
logically true (see Carnap 1931) and by the impact of Gödel’s incompleteness
theorems. Carnap’s solution was to employ a conventionalist
notion of logic and analyticity, relativized to the choice of language
according to his principle of logical tolerance, and it was also
dependent on using a broader notion of logical consequence, going
beyond formal deduction, to overcome the limitations on deductive
systems revealed by the incompleteness theorems.
Quine was greatly taken by this means of upholding empiricism,
though he soon had misgivings, which focused on the issue of
whether the distinction between analytic and synthetic, on which it
depended, could itself be drawn on an empiricist basis. It is a striking
fact that for all Quine’s initial enthusiasm for The Logical Syntax of
Language, he never published anything about it that he later had occasion
to retract. Thus the Harvard lectures, which expounded and
endorsed logical syntax, were never published (by him), and his review
of The Logical Syntax of Language, which he published in 1935,
did not endorse those key claims of Carnap’s. Here is a sentence from
the first of the three lectures on Carnap: “All such sentences, in
other words all mathematics and logic, become analytic: direct consequences
of our definitions, or conventions as to the use of words”
(Creath 1990, 60). And consider this ringing declaration of faith in
the analytic-synthetic distinction:
When we adopt such a syntax, in which the a priori is confined to the analytic,
every true proposition then falls into one of two classes: either it is
a synthetic empirical proposition, belonging within one or another of the
natural sciences, or it is an a priori analytic proposition, in which case it
derives its validity from the conventional structure, or syntax, of the language
itself – “syntax” being broadly enough construed to cover all linguistic
conventions. (p. 66)
This passage leads immediately to an endorsement of Carnap’s conception
of philosophy as separate from science, another point Quine
would later repudiate:
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