Abstract

Man is a rational animal, or so says Aristotle.1 But what is rationality? It is the use of reason to reach a certain level of reasonableness or unreasonableness. To be rational is to be extremely reasonable as to be irrational is to be extremely unreasonable. The varieties of rationality and distinctions about rationality are many. First of all, there is a distinction between practical and theoretical rationality. Secondly, there is a distinction between synchronic or static rationality and diachronic or dynamic rationality. Thirdly, there is a distinction between personal rationality and interpersonal rationality. Combinations of these kinds of rationality yield eight kinds of rationality.