Abstract

What makes us epistemically justified in believing the truths of logic and mathematics. What is the source, or nature, of that justification? Is it in some way ultimately grounded in sensory experiences? Or can it be grounded on reason and understanding alone? ;My aim in this dissertation is to develop a conception of non-perceptual intellection-based justification for belief and to argue that much knowledge of mathematics and logic has an intellection-based epistemic ground. The second objective is divided into three broad tasks. The first task is to argue that one can have a justification grounded on reason alone for believing propositions one takes to be obvious, i.e., propositions one holds as true just in virtue of understanding the proposition. Some of the arithmetical and logical beliefs justified on this basis may serve as premises for proofs of other propositions. The second task is to show that the lengthiness of a proof does not normally alter the epistemic character of the prover's justification for believing the derived proposition. The increased susceptibility to error due to length in performing the proof does not necessitate the introduction of empirical elements into the justification. Some of the arguments given to fulfill these first two tasks assume that agents have knowledge of their own thoughts and beliefs. The third task is therefore to explicate why the epistemic ground of knowledge of one's own thought is itself dependent upon reason and understanding, not on sensation or perception. This rationalist project sharpens the significance of the distinctive types of justificatory procedures used in mathematics and logic; and it may contribute to showing wherein our ability to have such knowledge marks something distinctive about being reflective reasoners