Aquinas on Self-Knowledge

Aquinas distinguishes two kinds of self-knowledge. The intellect, he says, knows itself in two ways: In the first place, singularly, as when Socrates or Plato perceives that he has an intellectual soul because he perceives that he understands. In the second place, universally, as when we consider the nature of the human mind from knowledge of the intellectual act. (ST I, 87, 1) Although the second kind of knowledge about the nature or essence of man raises interesting issues, in this paper I want to consider just one thesis ascribed to Aquinas as concerns the first kind of self-knowledge in which the intellect knows its own mental states (hereafter self-knowledge simpliciter). This is the thesis that what distinguishes human beings from animals is 'a selfreflexive power that allows them to have not only cognitions but also cognition of the truth of their cognitions'. (MacDonald 1993, 186) Call this the M-thesis. One interpretation of the M-thesis might seem trivial: what distinguishes humans from non-rational animals is not merely the fact that they are able to have concepts and produce thoughts on the basis of the concepts that they possess but also that the indispensable precondition of being a person is precisely the fact of human selfknowledge. For what use would our concepts and thinking be if we did not know what concepts we are having or what thoughts we are entertaining