  Quine is often thought to accept underdetermination. But in fact he holds that there is considerable difficulty in making non-trivial sense of the doctrine. He identifies theories with sets of sentences, not with sets of sentence-meanings (propositions). So we can quite trivially obtain an empirically equivalent alternative to any theory: simply spell one of the theoretical terms differently at every occurrence. Strictly speaking, the result is a different set of sentences which implies all the same observation categoricals (1975a, 319). The difference from the original theory, however, is merely orthographic; this possibility is clearly not of any philosophical significance.