Willard Van Orman Quine

238 daniel isaacson
differences but saw them as bridgeable. As for the accidental reasons,
the debate between Carnap and Quine is confused by the fact that
Carnap was moving to embrace modal logic, which Quine abhorred
(and, as noted, had done from before his contact with Carnap), at the
same time that Quine was coming to realize that he had fundamental
disagreements with Carnap’s philosophy of logical syntax, which
initially he had thought he accepted wholeheartedly.
This last point reflects a characteristic difference between Quine
and Carnap. Quine is a systematic philosopher and his philosophy is
nearly all of a piece. As noted, his first philosophical essay, “Truth
by Convention,” contains in germ many of the main elements of
his later philosophy, and there is nothing in that paper he later abandoned
or even significantly modified. Carnap’s thinking, by contrast,
while remaining true to some key aspirations, underwent more or
less substantial shifts, if not of content then of emphasis. Quine
engaged with three successive phases of Carnap’s philosophical development:
the logical construction of the world, the logical syntax
of language, and semantics. 26
What first attracted Quine to Carnap was Carnap’s contribution,
in his Logical Structure of the World, to the empiricist reduction of
knowledge of the external world to sensory data. In the end, Carnap’s
reduction did not live up to Quine’s or Carnap’s hopes for it. As Quine
describes the situation, “[T]he construction which Carnap outlined
in Der logische Aufbau der Welt does not give translational reduction....Wemust
despair of any such reduction. Carnap had despaired
of it by 1936, when, in ‘Testability and meaning,’ he introduced socalled
reduction forms of a type weaker than definition” (EN 76–7).
Quine’s doctoral student, and later colleague, Nelson Goodman devoted
his dissertation to the project, which gave rise to his book The
Structure of Appearance (1951). Quine’s own treatment focused on
characterizing a class of observation sentences and analyzing their
role in the edifice of what is known. Major treatments of it by Quine
occur in Word and Object, “Epistemology Naturalized,” Roots of
Reference, and From Stimulus to Science. This work of Quine’s carries
on from debates in the early 1930s within the Vienna Circle,
mostly between Carnap and Neurath, over protocol sentences. 27
By the time Quine came into personal contact with Carnap, Carnap’s
attention had moved on from the problem of the sensory basis of
empirical knowledge to the issue of how to show that all knowledge
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