The second dogma of Empiricism is the view that language is reducible to sense experiences. The original dogma was that the meaning of a term is the copy of a sense impression associated with that term. Thus, one sees a shoe. That is an impression. Then one remembers what they saw, calling it to mind. That is a copy of an impression. The word 'shoe' then means the image called to mind when we think of a shoe.
This fell out of use when Frege convinced everyone that meaning is tied not to terms, but to sentences. The logical positivists then argue that the meaning of any sentence other than a tautology is the method used to verify the truth of that sentence, and that method will come to the occurrence of specific sense impressions. But can all non-tautologies be reduced to sense experiences? Most Logical Positivists assume the answer to be 'yes.' Carnap actually tries to show what such a view would look like, and Quine focuses his critique on Carnap's attempt.
Carnap's view was also a sketch, but a more thorough sketch than any so far. That is, most people assumed the dogma to be true, but Carnap actually tries to do the reduction. His working insight? Using space-time points, the backbone of science, where "quadruples of real numbers"were assigned to sense qualities according to preset rules. The most basic statement forms to which all other sentences were either reducible or nonsensical were "Quality q is at point instant x, y, z, t." If that sensible quality were not there, the basic sentence is false, and more complex sentences were to be built from those basic sentences. Quine argues, however, that "Carnap did not seem to recognize, however, that his treatment of physical objects fell short of reduction not merely through sketchiness, but in principle." Indeed, Quine writes, "... it provides no indication, not even the sketchiest, of how a statement of the form 'Quality q is at point instant x, y, z, t' could ever be translated into Carnap's original language of sense data and logic. The connective 'is at' remains an added undefined connective; the canons counsel us in its use, but not in its elimination." Simply put, we cannot understand the final reduction in the terms the Logical Positivist requires. Their standards of meaningfulness are so high, the best attempt to actually reduce language to sense data, to sense impression, fails, too. Reduction to sense data and logic cannot be the final word in meaningfulness. the only way to do so uses words that are not reducible to either.All the handwaving 'there must be a way to reduce language to experience!' turns out to be just dogma, unsupported beliefs assumed to be true.
Carnap, Quine writes, seems to have accepted this as well. In Carnap's later writings, the whole reductionist project is gone.
What does Empiricism look like without the Dogma? If individual sentences are not the bearer of meaning, what is? How can we understand all knowledge being tied to experience if reductionism is false? That and more next time.