法律与经济学Papers and Proceedingsof the American Economic Review, (May 1978).

rescuer (nor to impose liability), the law recognizes the fragility of altruism and entitles the rescuer to a reward in certain instances.
These include rewards to professional rescuers on land (normally a
NBER Working Paper Series
ALTRUISM IN LAW AND ECONOMICS William N. Landes and Richard A. Posner University of Chicago Law School
Working Paper No.
217
CENTER FOR ECONOMIC ANALYSIS OF HUMAN BEHAVIOR AND SOCIAL INSTITUTIONS
ABSTRACT
A classic example of external benefits is the rescue of the
person or property of strangers In high transaction cost settings. To
illustrate, A sees a flowerpot about to fall on B's (a stranger's) head;
Partial support for this research was provided by a grant to the National Bureau of Economic Research from the National Science Foundation (No. S0C77—15657). The views set forth herein do not necessarily reflect those of the National Science Foundation.
This report has not undergone the review accorded official
NBER publications; in particular, it has not yet been submitted for approval by the Board of Directors.
ALTRUISM IN LAW AND ECONOMICS William M. Landes and Richard A. Posner*
The use of economics to understand the legal system has been
growing rapidly. This new field of applied economics is worthwhile
analysis of the law of rescue and explore its relevance to a variety of
economic questions not limited to the "law and economics't field.
Economists have discussed altruism——which we will initially define
legal methods of internalizing external benefits, though this depends
on the degree of altruisitu, the costs of rescue, and the benefits to
the rescuee. Although the general legal rule is not to reward the
save B. Either form of intervention, however, is apt to be quite costly.
Where, as in the example given, the rescuer is not engaged in the business of rescue, the appropriate reward, which from the standpoint of economics depends on the opportunity costs of A's time and his expected losses resulting from the dangerousness of the rescue, would be costly to
for its own sake in that the legal system is an important part of the
social system. But it is also interesting for its potential feedback into the analysis of economic problems in other fields. For example,
high transaction costs is to propose legal intervention. In the example
given, this would mean either giving A a right to a reward or punishing
A if he fails to save B. Either method, we show, is costly and may result in misallocative effects. These objections to using the law to
National Bureau of Economic Research, Inc. 204 Junipero Serra Boulevard, Stanford, CA 94305
November 1977
Preliminary; not for quotation.
NBER working papers are distributed informally and in limited number for comments only. They should not be quoted without written permission of thediscipline within a firm.2 This paper will examine
another area where the economic analysis of law appears to have implica-
tions for broader economic questions; we shall discuss the economic
confer a considerable benefit on B. However, it is infeasible for A
and B to contract for the rescue because of the lack of time for
4
negotiation.
The standard economic reaction to a situation in which there are substantial potential external benefits and high transaction costs is
the analysis of the social costs of crime has led to a change in the
thinking of economists about the monopoly problem.1 And recent work on
private law enforcement appears to have broad implications for the prob-
its answer.
—2—
I.
The peril that invites rescue provides a perfect example of
external benefits. A sees a flowerpot about to fall on B's (a stranger's)
head; if he shouts, B will be saved. A thus has it in his power to
physician) and to rescuers at sea. In both instances the costs of
rescue are likely to be sufficiently high to discourage rescue unless the rescuer anticipates compensation. —— W. M. Landes and R. A. Posner
victim of a criminal assault. The question of how to explain either
kind of conduct from the standpoint of economics is a challenging one. An examination of the legal regulation of rescue may provide clues to
if he shouts, B will be saved. A thus has in his power to confer a considerable benefit on B. The standard economic reaction to a situation in which there are substantial potential external benefits and
to propose legal intervention. In the example put, this would mean
giving A a right to either a public or private (presumably from B) reward for the service he renders in saving B; or punishing A if he fails to
as any transfer that is not compensated——mainly irt relation to transfers
within the family, and secondarily in relation to gifts to charity.3 Another important area of altruistic activity, however, concerns the rescue of the person or property of strangers. One reads in the newspapers about the passerby who jumps into the lake to save a drowning swimmer——and about the passerby who does nothing to assist the screaming
Internalize the external benefits of rescue would be much less imposing
were it not for altruism, a factor ignored in most discussion of
externalities. Altruism may be an inexpensive substitute for costly