From time to time I’ve had occasion to make use of examples where someone says different things to two different interlocutors in a single utterance. My favorite examples were pointing to a bottle and saying “Gift!”, which would mean a very different thing to a German speaker and to an English speaker, or using coded language while speaking to someone while knowing a spy is overhearing. Such examples illustrate the interesting fact that we cannot identify propositions with equivalence classes of utterance tokens, because a single utterance token can express different propositions.
But arguments based on such contrived cases have a tendency to be less than convincing. However, it has just occurred to me that dog whistles in politics are a real-life example of the same phenomenon, and one technically within a single language.
By the way, if we’re looking for equivalence classes that function like propositions, I guess instead of looking at equivalence classes of tokens utterances, we should look at equivalence classes of context-token pairs, where a context includes the language and dialect as well as the (actual? intended?) audience.
