ABSTRACT
I ONCE gave a series of talks to a group of psycho-analysts who had trained together and was rather struck by the statement made by one of them that, psychologically speaking, 'reason' means saying 'no' to oneself. Plato, of course, introduced the concept of 'reason' in a similar way in The Republic with the case of the thirsty man who is checked in the satisfaction of his thirst by the thought that the water may be poisoned. But Plato was also so impressed by man's ability to construct mathematical systems by reasoning that he called it the divine element of the soul. What has this ability to do with that of saying 'no' to oneself? And what have either of these abilities to do with the disposition to be impartial which is intimately connected with our notion of a reasonable man, or with what David Hume called a 'wonderful and unintelligible instinct' in our souls by means of which men are able to make inferences from past to future?
