That certain metaphysical discussions may be mere verbal disputes is a hotly debated topic in meta-metaphysics. Sometimes one has the impression that, while discussing the merits of their respective theories, philosophers are making the same claims about the world but phrased in different terminologies. It may be that everything that one philosopher says in their language can be translated to what the other philosopher says in their language. If so, wouldn’t they be making the same claims and having a moot discussion?
But when are then two metaphysical theories equivalent? Can we find specific criteria that would allow us to decide whether two given theories are metaphysically equivalent? I have worked on this topic with Bruno Jacinto (CFCUL):
- Jacinto, B.; Belastegui, J. (2023): Quineanism, Noneism and Metaphysical Equivalence. Studia Logica, 112, 1019–1090. DOI: 10.1007/s11225-023-10085-y
In this paper we propose some conditions under which metaphysical theories are equivalent, by taking the debate between quineans and noneists as a case study.
Noneists claim that there are some things that do not exist. Quineans claim that every thing exists. Whereas quineans think that noneists make non-sensical claims about existence, noneists think that quineans are missing an important distinction about the nature of existence.
One way to study this dispute is by providing an account of metaphysical equivalence between their theories that is based on intertranslatability. If quineans can express everything that noneists can express by using their own linguistic resources and vice versa, it means that their theories are equivalent. Under our account, for example, there are some distinctions that noneists can express that quineans cannot, and so their theories turn out not to be metaphysically equivalent.
In the process, we argue for specific conditions of intertranslatibility by considering the entailment structure of theories in terms of Agustín Rayo’s idea of how theories ‘carve up’ logical space. We also defend our view against other theories of metaphysical equivalence from the literature.