Critique of Rationalism in the Epistemology of Modality

Book excerpt: In this thesis, I critically discuss rationalism in epistemology of modality. Rationalism claims that our a priori intuition or conceivability gives us knowledge about metaphysical possibility. I examine this claim by considering Bealer's moderate rationalism and Chalmers's modal rationalism. In particular, I argue that Bealer's moderate rationalism is not successful in responding to Kripke's and Putnam's counterexamples which sever the link between a priori intuition and modal knowledge. Also, it is argued that given Chalmers's modal rationalism, our a priori conceivability entails more than metaphysical possibility from the perspective of our world. After providing some preliminary points in Introduction, I assess Bealer's moderate rationalism in Chapter 2. Specifically, I argue that our a priori intuition about epistemic possibility concerning property-identities does not give us knowledge about metaphysical possibility. In arguing this point, Russellian and Fregean theories of phenomenal content are discussed. Also, a priori unknowability of necessary properties of a substance is examined. In Chapter 3, I discuss an issue untouched by Bealer's moderate rationalism: a priori knowability of metaphysical possibility concerning property-possession of a substance. I argue that given Bealer's moderate rationalism, our a priori intuition does not give us knowledge about metaphysical possibility concerning that. In arguing this point, categoricalism and dispositionalism about the nature of properties are discussed. I examine Chalmers's modal rationalism in Chapter 4 and argue that our a priori conceivability can entail metaphysical possibility from perspectives of other worlds. Then, I derive a claim that we must be cautious not to commit a modal error of regarding what is not metaphysically possible from the perspective of our world as possible when we depend on a priori conceivability to know metaphysical possibility.