ABSTRACT
In 1963 Prior proved a theorem that places surprising constraints on the logic of intentional attitudes, like ‘thinks that’, ‘hopes that’, ‘says that’ and ‘fears that’. Paraphrasing it in English, and applying it to ‘thinks’, it states: If, at t, I thought that I didn’t think a truth at t, then there is both a truth and a falsehood I thought at t.
This chapter explores a response to this paradox that exploits the opacity of attitude verbs, exemplified in this case by the operator ‘I thought at t that’, to block Prior’s derivation. According to this picture, both Leibniz’s law and existential generalization fail in opaque contexts. In particular, one cannot infer from the fact that I’m thinking at t that I’m not thinking a truth at t, that there is a particular proposition such that I am thinking it at t. Moreover, unlike some approaches to this paradox (see Bacon et al., 2016) the failure of existential generalization is not motivated by the idea that certain paradoxical propositions do not exist, for this view maintains that there is a proposition that I’m not thinking a truth at t. Several advantages of this approach over the non-existence approach are discussed, and models demonstrating the consistency of this theory are provided. Finally, the resulting considerations are applied to the liar paradox, and are used to provide a non-standard justification of a classical gap theory of truth. One of the main challenges for this sort of theory—to explain the point of assertion, if not to assert truths—can be met within this framework.
