Harris Hatziioannou

I first examine and reject a prominent rationalist approach to knowledge of metaphysical modality, advocated by philosophers such as Yablo and Chalmers, who rely on the notion of conceivability to explain how we can achieve such knowledge. The focus of my criticism concerns a particular requirement of these accounts, namely that the content of modally reliable conceivability intuitions, which is in the first instance a simple imaginary situation, can be extended to completeness and thus considered to be verifiable by a range of possible worlds. I thus argue that the notions these philosophers employ cannot provide the criteria by which we could understand how such an operation could be understood in a purely epistemic way. This is because they rely on substantial metaphysical assumptions, for instance the assumption that all aspects of reality can in principle be represented and grasped by the human mind as a unified whole. These assumptions render their notion of conceivability inadequate to be used as an epistemic guide to possibility. Finally, I outline the broad epistemological principles that pertain to a specific Kripkean understanding of metaphysical necessity that I favor, which construes it as a kind of natural necessity.