Abstract

This article argues for the thesis that there is only one basic form of rationality, which is applied in different areas. First of all, there is one meaning of the term "rational" which applies to all situations in which the term is used: "justified." If "rational" means simply "justified", then rationality can be broken down into as many types as there are kinds of justification. Two distinctions between kinds of justification seem particularly plausible: 1. relative vs. absolute justifications and 2. theoretical justifications of opinions vs. practical justifications of actions. Taken together, these two distinctions yield a division into four types of rationality. I maintain, however, that these two distinctions collapse upon more careful examination. In this article I will simply assume that no form of ultimate justification is convincing; thus, the first distinction does not apply. Against the second distinction I try to argue in this paper that theoretical rationality represents a form of practical rationality. The idea of an optimal choice of aims, actions, and opinions, which nonetheless differs from the orthodox model of practical rationality, thus proves to be the comprehensive central ingredient of the concept of rationality.