Rationality

by

Patrick Rysiew

• LAST REVIEWED: 24 July 2018
• LAST MODIFIED: 21 November 2012
• DOI: 10.1093/obo/9780195396577-0175

Introduction

“Rationality” is among our central and most widely used evaluative notions. That humans are “rational animals” is a presumption built into the very name of our species, Homo sapiens; and the thought that humans are rational, perhaps distinctively so, appears to be part of the popular fabric of thought about ourselves. “Rational” and its complement “irrational” are standardly used, both in ordinary speech and across a variety of academic disciplines and subdisciplines, to describe persons, beliefs, actions, plans, policies, desires, decisions, institutions, and a host of other things. It is widely agreed that lying behind this richness of use is a general division between “theoretical” or “epistemic” rationality and “practical” rationality. But that distinction goes only so far in regimenting the concept and the issues with which it is bound up. Because it is a term that is used in so many ways, and with regard to such a wide range of topics and subjects, it does not admit of any neat analysis. Some have despaired of its being a useful general theoretical notion at all. Given its centrality, however, it is better to map the notion in its various principal employments than to try to get by without it. This entry lays out those employments and describes some of the main issues arising in connection with the notion of rationality.

General Overviews

Because “rationality” is used in so many ways, and with regard to such a wide range of topics and subjects even within philosophy, there are very few sources that give a decent sense of the subject as a whole. Books whose titles suggest a general treatment usually end up being rather partial, focusing on particular issues within specific subject areas. Although The Stanford Encyclopedia of Philosophy has some excellent entries on specific topics relating to rationality (practical reasoning, moral reasoning, etc.), it is telling that no general entry on the subject is attempted. Even so, there are some books that, although hardly representing the whole range of issues and topics treated under the heading of “rationality,” provide useful general entries into the subject. Nozick 1993 presents his own theory of rationality, providing accounts of what makes for both rational decisions and rational beliefs. Audi 2001 does the same, as well as criticizing some central Nozickian ideas. Neither of these books is meant to be an impartial overview, but their ambitiousness, and the talents of the authors, make them very good overviews of some of the main features of the relevant philosophical terrain.

• Audi, Robert. The Architecture of Reason: The Structure and Substance of Rationality. Oxford: Oxford University Press, 2001.

  The goal is to bring together practical and theoretical rationality in a unified theory. Ultimately, this is done service by trying to come up with a theory of “global” rationality—the overall rationality of persons. Audi is a leading epistemologist, and epistemological issues get more attention here than in Nozick 1993.

• Nozick, Robert. The Nature of Rationality. Princeton, NJ: Princeton University Press, 1993.

  Taking the capacity for rationality to be what demarcates humans, Nozick attempts a unified account of the phenomenon. The discussion brings together issues and theories from across philosophical subject areas, including epistemology (theory of knowledge), decision theory, ethics, philosophy of biology, and more.