Revising a system of beliefs › Logical truth and the problem of synonymy

In §1, Quine separates two kinds of examples commonly called analytic. A logical truth remains true when its nonlogical vocabulary is reinterpreted while the logical structure is held fixed. For a simple illustration, "If a visitor is early, that visitor is early" retains its form whatever property replaces being early. The repeated predicate does the relevant work.

Other apparent analytic truths depend on vocabulary with substantive meanings. To treat the vixen example as a logical truth, we first replace "vixen" with "female fox." That replacement depends on synonymy, or sameness of meaning. The logical structure alone does not license exchanging arbitrary predicates. If the proposed account of analyticity uses synonyms, it still owes us an explanation of the relevant sameness.

The difficulty is easy to miss because competent speakers can already make many of the intended judgments. Quine is asking for an explanation of their status, not an admission that ordinary speakers are helpless with dictionaries. Knowing how to use a distinction and explaining why it supports a philosophical theory are different achievements.

Reference does not settle the question. Two descriptions can pick out the same object through different information. For an invented example, "the owner of this bicycle" and "the person who rented the upstairs flat" might identify the same person. Discovering that identity could require investigation. Substituting one description for the other would then preserve reference without making the discovery a consequence of vocabulary alone.