ABSTRACT
This chapter explores the connection between the principle of contrariety and Aristotle's theory of the soul. The activities of the soul are special cases of natural processes and as they involve the principle of contrariety. Soul is both the first actuality of living organisms and the final cause of all behaviour; and equally so the source of the self-moving capacity of life. Considering the vagueness that characterized the entirety of pre-Aristotelian theories on the nature of the soul and its processes, the contribution of Aristotle in this field of knowledge is without exaggeration a scientific revolution. Aristotle's conception of psychology also points to the other direction, that of the formal and social sciences. The picture of Aristotle's criticism becomes complete only when one considers the additional fact that it is done from the particular standpoint of his own theory, and he reformulated these theories in order to give them the appearance of plausible psychological hypotheses.
