Climbing the hyperintensional mountain : an essay on impossible worlds, subject matters and truthmakers

Starting with considerations on why one would want hyperintensional theories of content, this thesis engages in an exploration of three main strands in contemporary hyperintensional semantics and metaphysics: impossible worlds semantics, subject matter theory and truthmaker semantics. Its central claim is that the best hyperintensional theories for various purposes use important insights from these three ways of doing semantics. Starting with a space of possible worlds and expanding it, as Berto and Jago (2019) do, to a space of ‘open’ impossible worlds, we get too anarchic a space of worlds, however closing it under any logical consequence relation, like FDE, we idealize too much if our goal is to model realistic epistemic agents. Adding subject matters (Silva, 2024a) helps to find a happy middle ground. This leaves open the question of how to characterize subject matters, and here the notion of exact verification, I argue, helps in defining a new notion of what we may call `topical truthmaking' which in turn helps define the notion of a subject matter. Closing the circle, recently Berto and Jago (2023) have argued that truthmaker semantics and impossible worlds semantics are notational variants of one another, save for the former’s emphasis on exact verification. I myself argue for this equivalence (Silva, 2024c) by showing that the ontology presupposed by standard truthmaker semantics, as presented in (Fine, 2017a), is the same as the one employed by Berto and Jago (2019). Having developed the aforementioned theoretical background in the first part of the thesis, I then apply the hyperintensional framework in the second part. Namely, I do so to: epistemic logic; the demarcation of the logical vocabulary; and transfeminist philosophy. Longer proofs were saved for a formal appendix.