Invariantist ‘might’ and modal meaning change

Invariantism proposed by [Braun, 2013] aims to maintain full identity of semantic content between all uses of ‘might’. I invoke well-known facts regarding diachronic change in meanings of modals to argue that invariantism commits us to implausible duplication of familiar processes of lexical semantic change on the level of “lexical pragmatics”, with no obvious payoff. [Braun, 2013] proposes an invariantist theory of ‘might’, which analyzes the literal semantic content of ‘might’ as extremely weak: according to Braun, ‘might p’ is semantically true iff p is possible on any possible notion of possibility. Those notions include epistemic possibility, metaphysical possibility, deontic possibility, and so forth. Under this semantics, ‘might p’ will be true for practically every imaginable p in practically every imaginable context: for example, if p is metaphysically impossible, but somebody doesn’t know that, ‘might p’ would still be true on the literal meaning. Obviously, speakers usually use ‘might p’ statements to convey something much stronger. Braun argues that it is because in addition to literally conveying (locuting, in Braun’s terms, which I accept for the purposes of this paper) a very weak proposition by uttering ‘might p’, speakers also express (in Braun’s terms, assert) a much stronger one. Thus Mrs. Hudson uttering Holmes might be in Paris would normally assert by that utterance a claim much stronger than the weak literal meaning of the sentence — for instance, the assertion may be “It is compatible with Mrs. Hudson’s knowledge that Holmes is in Paris”. [Braun, 2013]’s invariantism is supposed to apply not only to ‘might’, but to many, or perhaps all, modal words (Braun explicitly mentions ‘must’, ‘possible’ and ‘necessary’). Invariationism may seem a crazy theory, but it is not. Once we consider sentences like I graded a million exams yesterday, it becomes apparent that the proposition the speaker intends to assert may be plausibly taken to be quite different from the one literally expressed by the uttered sentence. Thus there is no reason to reject the invariantist explanation out of hand. I refer the reader to [Braun, 2013] for a fuller justification. What I argue in this note is that despite being a reasonable theory, invariantism commits us to a quite implausible duplication of familiar mechanisms of semantic diachronic change