Paul Boghossian

Paul Boghossian
Christopher Peacocke
1. Identifying the A Priori

An a priori proposition is one which can be known to be true without any justification from the character of the subject's experience.

A specification of the way in which something comes to be known will include at least a tree-structure of events and states which are causes of the knowledge, together with some specification of why the thinker makes the transitions it involves.

The proof itself provides an entitlement to belief in its last line.

Perception of the written proof gives access to that entitlement, but is not itself part of that entitlement.

On this approach, an a priori proposition is one such that there is a way of coming to know it under which the thinker's entitlement to accept the proposition does not involve the character of the thinker's experience.

An a posteriori proposition is one such that any way of coming to know it will involve an entitlement which does concern the character of the thinker's experience.

some rationalists, including Frege, have distinguished certain ways as philosophically more fundamental, or canonical, in an account of justification. Some ways of coming to know may be a priori, but rather indirect, as in certain proofs by reductio ad absurdum.

The distinction between canonical and non-canonical ways of coming to know is not, however, employed by everyone who has used the notion of the a priori.

In the case of a priori propositions, much experience, perhaps of a specific character, may be required to grasp the concepts implicated in the proposition or to access the entitlement to believe it; but conditions of grasp and of access remain distinct from the nature of the entitlement.