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What Shanl We Mam?
The Tragedy of the Commons
The population problem has no technical solution;
it requires a fundamental extension in morality.
Garrett Hardin
At the end of a thoughtful article on
the future of nuclear war, Wiesner and
York (1) concluded that: "Both sides in
the arms race are ... confronted by the
dilemma of steadily increasing military
power and steadily decreasing national
security. It is our considered profes-
sional judgment that this dilemma has
no technical solution. If the great pow-
ers continue to look for solutions in
the area of science and technology only,
the result will be to worsen the situa-
tion."
I would like to focus your attention
not on the subject of the article (na-
tional security in a nuclear world) but
on the kind of conclusion they reached,
namely that there is no technical solu-
tion to the problem. An implicit and
almost universal assumption of discus-
sions published in professional and
semipopular scientific journals is that
the problem under discussion has a
technical solution. A technical solution
may be^ defined as one that requires a
change only in. the techniques of the
natural sciences, demanding little or
nothing in the way of change in human
values or ideas of morality.
In our day (though not in earlier
times) technical solutions are always
welcome. Because of previous failures
in prophecy, it takes courage to assert
that a desired technical solution is not
possible. Wiesner and York exhibited
this courage; publishing in a science
journal, they insisted that the solution
to the problem was not to be found in
the natural sciences. They cautiously
qualified their statement with the
phrase, "It is our considered profes-
The author is professor of biology, University of (^) California, Santa Barbara. This (^) article is based on a presidential address (^) presented before the (^) meeting of the Pacific Division of the (^) Ameri- can Association for the Advancement (^) of Science at Utah State (^) University, Logan, 25 June 1968.
13 DECEMBER 1968
sional judgment... ." Vhether they
were right or not is not the concern of
the present article. Rather, the concern
here is with the important concept of a
class of human problems which can be
called "no technical solution problems,"
and, more specifically, with the identifi-
cation and discussion of one of these.
It is (^) easy to show that the class is not a null class. Recall the game of tick-
tack-toe. Consider the problem, "How
can I win. the game of tick-tack-toe?"
It is well known that I cannot, if I as-
sume (in keeping with the conventions
of game theory) that my opponent (^) un-
derstands the game perfectly. Put an-
other way, there is (^) no "technical solu-
tion" to the problem. I can win only
by giving a^ radical meaning to the word
"win." (^) I can hit my opponent over the
head; or I can drug him; or I can falsify
the records. Every way in which I "win"
involves, in some sense, an abandon-
ment of the game, as we intuitively un-
derstand it. (I can also, of course,
openly abandon the game-refuse to
play it. This is what most adults do.)
The class (^) of "No technical solution
problems" has members. My thesis is
that the "population problem," as con-
ventionally conceived, is a member of
this class. How it is conventionally con-
ceived needs some comment. It is fair
to say that most people who' anguish
over the population problem are trying
to find a way to avoid the evils of over-
population without relinquishing any of
the privileges they now enjoy. They
think that farming the seas or develop-
ing new strains of wheat will solve the
problem-technologically. I try to show
here that the solution they seek cannot
be found. The population problem can-
not be solved in a technical way, any
more than can the problem of winning
the game of tick-tack-toe.
Population, as^ Malthus^ said,^ naturally
tends to grow "geometrically," or, as we
would now say, exponentially. In a
finite world this means that the per
capita share^ of^ the^ world's^ goods must
steadily decrease.^ Is^ ours^ a^ finite^ world?
A fair defense can be put forward for
the view that the world is infinite; or
that we do not know that it is not. But,
in terms of the practical problems that
we must face in the next few genera-
tions with the foreseeable technology, it
is clear that we will greatly increase
human misery if we do not, during the
immediate future, assume that the world
available to the terrestrial human pop-
ulation is finite. "Space" is no escape
A finite world can support only a
finite population; therefore, population
growth must^ eventually equal zero.^ (The
case of perpetual wide fluctuations
above and below zero is a (^) trivial variant
that need not be discussed.) When this
condition is met, what will be the situa-
tion of mankind? Specifically, can Ben-
tham's goal of "the greatest good for
the greatest number" be realized?
No-for two reasons, each sufficient
by itself. The^ first^ is^ a^ theoretical one.
It is not mathematically possible to
maximize for two (or more) variables at
the same time. This was clearly stated
by von^ Neumann^ and^ Morgenstern (3),
but the principle is implicit in the theory
of partial differential equations, dating
back at least to D'Alembert (1717-
The second reason springs directly
from biological facts. To live, any
organism must^ have^ a^ source^ of^ energy
(for example, food). This^ energy is
utilized for two puposes: mere main-
tenance and work. For man, mainte-
nance of life requires about 1600 kilo-
calories a day ("maintenance calories').
Anything that^ he does^ over^ and^ above
merely staying alive^ will be^ defined as
work, and is^ supported by "work cal-
ories" which he takes in. Work calories
are used not only for what we call work
in common speech; they are also re-
quired for^ all^ forms^ of^ enjoyment, from
swimming and automobile racing to
playing music^ and^ writing poetry. If
our goal is to maximize population it is
obvious what we must do: We must
make the work calories per person ap-
proach as^ close^ to^ zero as possible. No
gourmet meals, no vacations, no sports,
no music, no literature, no art.... I
think that everyone will grant, without
argument or proof, that maximizing
population does not max2imize goods.
Bentham's goal is impossible.
In reaching this conclusion I have
made the usual assumption that it is
the acquisition of energy that is the
problem. The appearance of atomic energy has led some to question this assumption. However, given an infinite source of energy, population growth
still produces an inescapable problem.
The problem of the acquisition of en-
ergy is replaced by the problem of its
dissipation, as J. H. Fremlin has so wit-
tily shown (4). The arithmetic signs in
-t-he analysis are, as it were, reversed;
but Bentham's goal is still unobtainable.
The optimum population is, then, less
than the maximum. The difficulty of
defining the optimum is enormous; so
far as I know, no one has seriously
tackled this problem. Reaching an ac-
ceptable and stable solution will surely
require more than one generation of
hard analytical work-and much per-
suasion.
We want the maximum good per
person; but what is good? To one per-
son it is wilderness, to another it is ski
lodges for^ thousands. To one it is estu-
aries to nourish ducks for hunters^ to
shoot; to another it is factory land.
Comparing one good with another is,
we usually say, impossible because
goods are incommensurable. Incommen-
surables cannot be compared.
Theoretically this may be true; but in
real life incommensurables are commen-
surable. Only a^ criterion of^ judgment
and a system of weighting are^ needed.
In nature the criterion is survival. Is it
better for a species to be small and hide-
able, or large and powerful? Natural
selection commensurates the incommen-
surables. The compromise achieved de-
pends on a natural weighting of the
values of the variables.
Man must imitate this process. There
is no doubt that in fact he already does,
but unconsciously. It is when the hidden
decisions are made explicit that the
arguments begin. The problem for the
years ahead is to work out an accept-
able theory of weighting. Synergistic
effects, nonlinear variation, and difficul-
ties in discounting the future make the
intellectual problem difficult, but^ not
(in principle) insoluble.
Has any cultural group solved^ this
practical problem at the^ present time,
even on an^ intuitive level? One^ simple
fact proves that^ none^ has:^ there is^ no
prosperous population in^ the^ world^ to-
day that has, and has^ had for^ some
time,-p - rate of zero. Any people
that has intuitively identified its opti-
mum point will soon reach it, after
which its growth rate becomes and re-
mains zero.
Of course, a positive growth rate
might be taken as evidence that a pop-
ulation is below its optimum. However,
by any reasonable standards, the most
rapidly growing populations on earth
today are (in general) the most misera-
ble. This association (which need not be
invariable) casts doubt on the optimistic
assumption that the positive growth rate
of a population is evidence that it has
yet to reach its optimum.
We can make little progress in work-
ing toward optimum poulation size until
we explicitly exorcize the spirit of
Adam Smith in the field of practical
demography. In economic affairs, The
Wealth of Nations (1776) popularized
the "invisible hand," the idea that an
individual who "intends only his own
gain," is, as it were, "led by an invisible
hand to promote. (^) .,. the public interest"
(5). Adam Smith did not assert that
this was invariably true, and perhaps
neither did any of his followers. But he
contributed to a dominant tendency of
thought that has ever since interfered
with positive action based on rational
analysis, namely, the tendency to as-
sume that decisions reached individually
will, in fact, be the best decisions for an
entire society. If this assumption is
correct it justifies the continuance of
our present policy of laissez-faire in
reproduction. If it is correct we can as-
sume that men will control their individ-
ual fecundity so as to produce the opti-
mum population. If the assumption is
not correct, we need to reexamine our
individual freedoms to see which ones are defensible.
Tragedy of Freedom in a Commons
The rebuttal to the invisible hand in
population control^ is^ to^ be^ found in^ a
scenario first sketched in a little-known
pamphlet (6) in 1833 by a mathematical
amateur named William Forster Lloyd
(1794-1852). We may well call it^ "the
tragedy of the commons," using the
word "tragedy" as the philosopher
Whitehead used it (7): "The^ essence^ of
dramatic tragedy is^ not^ unhappiness. It
resides in the solemnity of the^ remorse-
less working of things." He^ then'^ goes on.
to say, "This^ inevitableness^ of^ destiny
can only be^ illustrated^ in^ terms^ of hu-
man life by incidents which in fact in-
volve unhappiness. For it is only by
them that the futility of escape can be
made evident in the drama."
The tragedy of the commons develops
in this way. Picture a pasture open to
all. It is to be expected that each herds-
man will try to keep as many cattle as
possible on the commons.^ Such^ an ar-
rangement may work reasonably satis-
factorily for centuries because tribal
wars, poaching, and disease keep the
numbers of both man and beast well
below the carrying capacity of the land.
Finally, however, comes the day of
reckoning, that is, the^ day when the
long-desired goal of social stability be-
comes a reality. At this point, the in-
herent logic of the commons remorse-
lessly generates tragedy.
As a rational being, each herdsman
seeks to maximize his gain. Explicitly
or implicitly, more or less consciously,
he asks, "What is the utility to me of
adding one more animal to my herd?"
This utility has one negative and one
positive component.
- The positive component is a func-
tion of the increment of one animal.
Since the herdsman receives all the
proceeds from the sale of the additional
animal, the positive utility is nearly +1.
2) The negative component is a func-
tion of^ the^ additional^ overgrazing
created by one^ more^ animal.^ Since,
however, the effects^ of^ overgrazing are
shared by all the herdsmen, the^ negative
utility for any particular decision-
making herdsman is only a^ fraction^ of
Adding together the component par-
tial utilities, the rational herdsman
concludes that the only sensible course
for him to pursue is to add another
animal to his herd. And^ another; and
another.... But this is the conclusion
reached by each and^ every rational
herdsman sharing a^ commons.^ Therein
is the tragedy. Each man is locked into
a system that compels him to^ increase
his herd without limit-in^ a^ world^ that
is limited. Ruin is^ the destination^ to-
ward which^ all^ men^ rush, each^ pursuing
his own best interest in a society that
believes in the freedom of the com-
mons. Freedom in a commons brings
ruin to all.
Some would say that this^ is^ a^ plati-
tude. Would that it^ were!^ In^ a^ sense, it
was learned thousands of^ years ago, but
natural selection favors^ the forces of
psychological denial^ (8). The individual
benefits as an^ individual^ from^ his^ ability
to deny the truth^ even^ though society as
a whole, of which he is a part, suffers.
SCIENCE, VOL. 162
watch the watchers themselves?" John
Adams said that we must have "a gov-
ernment of laws and not men." Bureau
administrators, trying to evaluate the morality (^) of acts in the total system, are
singularly liable to corruption, produc-
ing a government by men, not laws.
Prohibition is easy to legislate
(though not necessarily to enforce); but
how do we legislate temperance? Ex-
perience indicates that it can be ac-
complished best through the mediation of administrative law. We limit possi-
bilities unnecessarily if we suppose that
the sentiment of Quis custodiet denies
us the use of administrative law. We should rather retain the phrase as a perpetual reminder of fearful dangers we cannot avoid. The great challenge
facing us now is to invent the corrective
feedbacks that are needed to keep cus-
todians honest. We must find ways to
legitimate the needed authority of both
the (^) custodians and the corrective feed-
backs.
Freedom To Breed Is Intolerable
The tragedy of the commons is in-
volved in population problems in an-
other way. In a world governed solely
by the principle of "dog eat dog"-if
indeed there ever was such a world-
how many children a family had would
not be a matter of public concern.
Parents who bred too exuberantly would
leave fewer descendants, not more, be-
cause they would be unable to care
adequately for their children. David
Lack and others have found that such a
negative feedback demonstrably con-
trols the fecundity of birds (11). But
men are not birds, and have not acted
like them for millenniums, at least.
If each human family were depen-
dent only on its own resources; if the
children of improvident parents starved
to death; if, thus, overbreeding brought
its own "punishment" to the germ line-
then there would be no public interest
in controlling the breeding of families.
But our society is deeply committed to
the welfare state (12), and hence is
confronted with another aspect of the
tragedy of^ the^ commons.
In a welfare state, how shall we deal
with the family, the religion, the race,
or the class (or indeed any distinguish-
able and cohesive group) that adopts
overbreeding as^ a^ policy to^ secure^ its
own aggrandizement (13)? To couple
the concept of^ freedom^ to^ breed with
the belief that everyone born has an
equal right to the commons is to (^) lock the world into a tragic course of action. Unfortunately this is just the course of action that is being pursued by the United Nations. In late 1967, some 30 nations agreed to the following (14): The Universal Declaration of (^) Human Rights describes the family as the natural and fundamental unit of society. It fol- lows that any choice and decision with regard to the size of the family must irte- vocably rest with the family itself, and cannot be made by anyone else. It is painful to have to deny (^) categor- ically the validity of this right; denying
it, one feels as uncomfortable as a resi-
dent of Salem, Massachusetts, who
denied the reality of witches in the 17th century. At the present time, in liberal quarters, something like a taboo acts to
inhibit criticism of the United Nations.
There is a feeling that the United
Nations is "our last and best hope,"
that we shouldn't find fault with it; we
shouldn't play into the hands of the
archconservatives. However, let us not
forget what Robert Louis Stevenson
said: "The truth that is suppressed by
friends is the readiest weapon of the
enemy." If we love the truth we must
openly deny the validity of the Universal
Declaration of Human Rights, even
though it is promoted by the United
Nations. We should also join with
Kingsley Davis (15) in attempting to
get Planned Parenthood-World Popula-
tion to see the error of its ways in em-
bracing the same tragic ideal.
Conscience Is Self-Eliminating
It is a mistake to think that we can
control the breeding of mankind in the
long run by an appeal to conscience.
Charles Galton Darwin made this point
when he spoke on the centennial of the
publication of his grandfather's great
book. The argument is straightforward
and Darwinian.
People vary. Confronted with^ appeals
to limit breeding, some people will un-
doubtedly respond to^ the^ plea more
than others. Those who have more
children will produce a larger fraction
of the next generation than those with
more susceptible consciences. The dif-
ference will be accentuated, generation
by generation.
In C. G. Darwin's words: "It may
well be that it would take hundreds of
generations for the progenitive instinct
to develop in this way, but if it should
do so, nature would^ have^ taken her
revenge, and the^ variety Homo^ contra-
cipiens would become extinct and
would be replaced by the variety Homo
progenitivus" (16).
The argument assumes that con-
science or the desire for children (no
matter which) is hereditary-but heredi-
tary only in^ the^ most^ general formal
sense. The^ result will^ be^ the same
whether the attitude is transmitted
through germ cells, or exosomatically,
to use A. J. Lotka's term. (If one denies
the latter possibility as well as the
former, then what's the point of educa-
tion?) The argument has here been
stated in the context of the population
problem, but it applies equally well to
any instance in which society appeals
to an individual exploiting a commons to restrain (^) himself for the general
good-by means^ of his conscience. To
make such an appeal is to set up a
selective system that works toward the elimination of conscience from the race.
Pathogenic Effects of Conscience
The long-term disadvantage of an
appeal to conscience should be enough
to condemn it; but has serious short-
term disadvantages as well. If we ask
a man who is exploiting a commons to
desist "in the name of conscience,"
what are we saying to him? What does
he hear?-not only at the moment but
also in the wee small hours of the
night when, half^ asleep, he remembers
not merely the words we used but also the nonverbal communication cues we gave him unawares? Sooner or later,
consciously or subconsciously, he senses
that he has received two communica-
tions, and that they are contradictory:
(i) (intended communication) "If^ you
don't do as we ask, we will openly con-
demn you for not acting like^ a respon-
sible citizen"; (ii) (the unintended
communication) "If you do behave as
we ask, we will secretly condemr. you
for a simpleton who can be shamed
into standing aside while the rest of us
exploit the commons."
Everyman then is caught in what
Bateson has called a "double bind." Bateson (^) and his co-workers have made
a plausible case for viewing the double
bind as an important causative factor in
the genesis of schizophrenia (17). The
double bind may not always be so
damaging, but^ it^ always endangers the
mental health of (^) anyone to whom it is
applied. "A bad conscience," said
Nietzsche, "is a kind of illness."
To conjure up a conscience in others
SCIENCE, VOL. 162
is tempting to anyone who wishes to
extend his control beyond the legal
limits. Leaders at the highest level
succumb to this temptation. Has^ any
President during the past generation
failed to call on labor unions to moder-
ate voluntarily their demands for higher
wages, or to steel companies to honor
voluntary guidelines on prices? I can
recall none. The rhetoric used on such
occasions is designed to produce feel-
ings of guilt in noncooperators.
For centuries it was assumed without
proof that guilt was a valuable, perhaps
even an indispensable, ingredient of the
civilized life. Now, in this post-Freudian
world, we doubt it. Paul Goodman (^) speaks from the modern point (^) of view when he says:
"No good has ever come from feeling
guilty, neither intelligence, policy, nor
compassion. The guilty do not pay
attention to the object but only to them-
selves, and not even to their own in-
terests, which might make sense, but to
their anxieties" (18).
One does not have to be a profes-
sional psychiatrist to see the conse-
quences of anxiety. We in the Western
world are just emerging from a dreadful
two-centuries-long Dark Ages of Eros
that was sustained partly by prohibi-
tion laws, but perhaps more effectively
by the anxiety-generating mechanisms
of (^) education. Alex Comfort has told the
story well in The Anxiety Makers (19);
it is not a pretty one.
Since proof is difficult, we may even
concede that the results of anxiety may
sometimes, from certain points of view,
be desirable. The larger question we
should ask is whether, as a matter of
policy, we should ever encourage the
use of a (^) technique the tendency (if not
the intention) of which is psycholog-
ically pathogenic. We hear much talk
these days of responsible parenthood;
the coupled words are incorporated
into the titles of some organizations de-
voted to birth control. Some people
have proposed massive propaganda
campaigns to instill responsibility into
the nation's (or the world's) breeders.
But what is the meaning of the word
responsibility in this context? Is it not
merely a synonym for the word con-
science? When we use the word re-
sponsibility in the absence of substantial
sanctions are we not trying to browbeat
a free man in a commons into acting
against his own interest? Responsibility
is a verbal counterfeit for a substantial
quid pro quo. It is an attempt to get
something for nothing.
13 DECEMBER 1968
If the word responsibility is to be
used at all, I suggest that it be in the
sense Charles Frankel uses it (20).
"Responsibility," says this philosopher,
"is the product of definite social ar-
rangements." Notice that Frankel calls
for social arrangements-not propa-
ganda.
Mutual Coercion
Mutually Agreed upon
The social arrangements that produce
responsibility are arrangements that
create coercion, of some sort. Consid-
er bank-robbing. The man who takes
money from a bank acts as if the bank
were a commons. How do we prevent
such action? Certainly not by trying to
control his behavior solely by a verbal
appeal to his sense of responsibility.
Rather than rely on propaganda we
follow Frankel's lead and insist that a bank (^) is not a commons; we seek the definite social arrangements that will
keep it from becoming a commons.
That we thereby infringe on the free-
dom of would-be robbers we neither
deny nor^ regret.
The morality of bank-robbing is
particularly easy to understand because
we accept complete prohibition of this
activity. We are willing to say "Thou
shalt not rob banks," without providing
for exceptions. But temperance also can
be created by coercion. Taxing is a good
coercive device. To keep downtown
shoppers temperate in their use of
parking space we introduce parking
meters for short periods, and traffic
fines for longer ones. We need not
actually forbid a citizen to park as long
as he wants to; we need merely make it
increasingly expensive for him to do so.
Not prohibition, but carefully biased
options are what we offer him. A Madi-
son Avenue man might call this per-
suasion; I prefer the greater candor of
the word coercion.
Coercion is a dirty word to most
liberals now, but it need not forever be
so. As with the four-letter words, its
dirtiness can be cleansed away by ex-
posure to the light, by saying it over and
over without apology or embarrassment.
To many, the word (^) coercion implies
arbitrary decisions of distant and irre-
sponsible bureaucrats; but this is not a
necessary part of its meaning. The only
kind of coercion I recommend is mutual
coercion, mutually agreed upon by the
majority of the people affected.
To say that we (^) mutually agree to
coercion is not to say that we are re-
quired to^ enjoy it, or^ even^ to^ pretend
we enjoy it. Who enjoys taxes? We all
grumble about^ them.^ But^ we accept
compulsory taxes^ because^ we^ recognize
that voluntary taxes would favor the
conscienceless. We institute and (grum-
blingly) support taxes^ and^ other^ coercive
devices to escape the horror of the
commons.
An alternative to the commons need
not be perfectly just to be preferable.
With real estate and (^) other material
goods, the^ alternative^ we^ have chosen
is the institution of private property
coupled with^ legal inheritance.^ Is this
system perfectly just? As^ a^ genetically
trained biologist I deny that it is. It
seems to me that, if there are to be dif-
ferences in individual inheritance, legal
possession should^ be^ perfectly cor-
related with biological inheritance-that
those who are biologically more fit to
be the custodians of property and (^) power
should legally inherit more. But genetic
recombination continually makes a
mockery of^ the^ doctrine^ of^ "like^ father,
like son" implicit in our laws of legal in-
heritance. An idiot can inherit millions,
and a trust fund can keep his estate
intact. We must admit that our legal
system of^ private property plus inheri-
tance is unjust-but we put up with it
because we are not convinced, at the
moment, that anyone has invented a
better system. The alternative of the
commons is too horrifying to contem-
plate. Injustice is^ preferable to total
ruin.
It is one of the peculiarities of the
warfare between reform and the status
quo that it is thoughtlessly governed
by a^ double^ standard.^ Whenever a re-
form measure is proposed it is often
defeated when its opponents trium-
phantly discover a flaw in it. As Kings-
ley Davis has^ pointed out^ (21), worship-
pers of the status quo sometimes imply
that no reform is possible without unan-
imous agreement, an implication con-
trary to historical fact. As nearly as I
can make out, automatic rejection of
proposed reforms is based on one of
two unconscious assumptions: (i) that
the status quo is perfect; or (ii) that the
choice we face is between reform and
no action; if the proposed reform is
imperfect, we presumably should take
no action at all, while we wait for a
perfect proposal.
But we can never do nothing. That
which we have done for thousands of
years is also action. It also produces
evils. Once we are aware that the
