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60 Geo. Wash. L. Rev. 293 (1991-1992)
Rationality in Law and Economics

handle is hein.journals/gwlr60 and id is 301 raw text is: Rationality in Law & Economics

Herbert Hovenkamp*
L   Introduction: The Role of Rationality Assumptions
in Law & Economics
Law & economics cannot exist without some theory of human ra-
tionality. Economists model and attempt to predict individual be-
havior on the assumption that people act rationally with the goal of
maximizing their expected utility.' Likewise, economists assume
that firms act rationally to maximize profits.2
Law & economics adds two important insights to these basic eco-
nomic notions of rationality. The first insight is that a person's cal-
culation of the utility maximizing course of conduct is affected by
the presence of legal penalties or rewards. For example, driving at
100 miles per hour may be rational when someone considers only
the urgency of the situation and the risk of an accident given her
driving skills; but it may cease to be rational when one also consid-
ers that the speed limit is forty miles per hour and is strictly en-
forced. To the extent that legal penalties change the cost-benefit
calculus, rational actors will respond accordingly.
* Ben V. & Dorothy Willie Professor of Law, University of Iowa College of Law.
Thanks to Randall Thomas for reading an earlier draft and to participants in a works-in-
progress seminar given at the George Washington University National Law Center.
1. See RICHARD A. POSNER, ECONOMIC ANALYSIS OF Law 3 (3d ed. 1985) (The task
of economics... is to explore the implications of assuming that man is a rational maxi-
mizer of his ends in life.). On the meaning of economic rationality, see generally,
SHAUN H. HEAP, RATIONALITY IN ECONOMICS 1 (1989); HERBERT A. SIMON, MODELS OF
BOUNDED RATIONALITY (1982) (surveying how various assumptions of rationality help
explain economic behavior).
2. See, e.g., EDWIN MANSFIELD, MICROECONOMICS: THEORY AND APPLICATIONS 151-
54 (5th ed. 1985).
January 1992 Vol. 60 No. 2

293