ABSTRACT
The notion that our cognitive activities can be sharply divided into kinds which are fundamentally different from each other, knowing on the one hand and believing on the other, has a long philosophical history, and has endured a less chequered career than most philosophical notions of its antiquity. Knowing and believing are not properly to be called acts at all, but are dispositional in character. The traditional insistence on a difference in kind between all knowing and all believing is closely connected with the traditional distinction between a priori and empirical propositions, the first being held to be knowable, but the second only believable. The distinction between a priori and empirical propositions, and its relevance to the supposed difference in kind between knowledge and belief, can be pointed out in two ways, both emphasising the necessity of a priori propositions and the contingency of empirical propositions. Knowing and being sure are different and can be shown by quite simple considerations.
