The nature and sources of a priori justification

The dissertation maintains that a priori justification requires a non-experiential source of justification. Further, it is argued that a non-experiential source of justification involves only cognitive seemings as evidence to justify a belief.; Chapter one considers the question, in what sense is a priori justification independent of experience? Three theses are considered, each expresses a sense of independence allegedly necessary for a priori justification: source independence, defeasibility independence, and causal independence. I argue that defeasibility independence is not a necessary condition for a priori justification. I argue that source independence is a necessary condition for a priori justification. A priori justification must have a non-experiential source. Finally, I suggest that the issue of causal independence be deferred until the notion of a non-experiential source of justification has been clarified.; Chapter 2 deals with several recent accounts of the nature of non-experiential sources of justification. The views of Philip Kitcher, John Pollock, and Laurence BonJour are presented and evaluated in an attempt clarify the notion of a non-experiential source of justification.; Chapter three concerns the task of adequately distinguishing between experiential and non-experiential sources of epistemic justification. An argument against such a distinction is considered and rejected. Several proposals for distinguishing non-experiential sources of justification are considered. I put forth and defend the view that experiential sources of justification require sensory seemings while non-experiential sources of justification require only cognitive seemings. In light of this proposal, I suggest that a priori justification is independent in the sense required for the causal independence requirement introduced in Chapter one.; Chapter four examines Laurence BonJour's recent claims that a priori justification is indispensable to reasoning and that only a rationalist epistemology successfully accounts for a priori justification. I argue that neither conclusion is adequately supported by BonJour's arguments.; Finally, a concluding section summarizes the dissertation.