A comprehensive defence of the rationalist view that insight independent of experience is a genuine basis for knowledge.

The topic of a priori knowledge has been central to analytic philosophy for the past two centuries. Casullo's book, based on previously published and unpublished work, systematically addresses questions that have, since Kant, formed the core of the debate.

This book deals with questions about the nature of a priori knowledge and its relation to empirical knowledge. Until the twentieth century, it was more or less taken for granted that there was such a thing as a priori knowledge, that is, knowledge whose source is in reason and reflection rather than sensory experience. With a few notable exceptions, philosophers believed that mathematics, logic and philosophy were all a priori. Although the seeds of doubt were planted earlier on, by the early twentieth century, philosophers were widely skeptical of the idea that there was any nontrivial existence of a priori knowledge. By the mid to late twentieth century, it became fashionable to doubt the existence of any kind of a priori knowledge at all. Since many think that philosophy is an a priori discipline if it is any kind of discipline at all, the questions about a priori knowledge are fundamental to our understanding of philosophy itself.

This book is a collection of essays concerning the concept and existence of a priori knowledge, and the relationship between a priori knowledge and the related concepts of necessary truth and analytic truth.

For centuries philosophers have attached much importance to a priori knowledge, but recent work in epistemology and experimental philosophy has questioned this. Leading philosophers discuss explanations of the a priori, challenges to its existence, the status of intuition, and the justification of belief—topics at the centre of current debate.

Richard Swinburne offers an original treatment of a question at the heart of epistemology: what makes a belief a rational one, or one which the believer is justified in holding? He maps the various totally different and purportedly rival accounts that philosophers give of epistemic justification ('internalist' and 'externalist'), and argues that they are really accounts of different concepts. He distinguishes (as most epistemologists do not) between synchronic justification (justification at a time) and diachronic justification (synchronic justification resulting from adequate investigation) — both internalist and externalist. He argus that most kinds of justification are worth having because (for different reasons) indicative of truth. However, it is only justification of intermalist kinds that can guide a believer's actions. Swinburne goes on to show the usefulness of the probability calculus in elucidating how empirical evidence makes beliefs probably true: every proposition has an intrinsic probability (an a priori probability independent of empirical evidence) which may be increased or decreased by empirical evidence. This innovative and challenging book will refresh epistemology and rewrite its agenda.

Provides an accessible guide to the central questions and most recent areas of debate within the field of a priori knowledge by defending the idea that there is a priori knowledge and that this knowledge is important both in it own right and also for other areas of philosophy, such as metaethics, metaphysics, and philosophy of science.