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Articles

The Tragedy of the Commons

Garrett Hardin

The population problem has no technical solution; it requires a fundamental extension in

morality.

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 acific !ivision of the"merican "ssociation for the "dvancement of Science at Utah State University, #ogan,

$% &une '()*.

"t the end of a thoughtful article on the future of nuclear +ar, iesner and -or /'0

concluded that1 2Both sides in the arms race are ... confronted by the dilemma of steadily

increasingmilitary po+er and steadily decreasing national security.It isour consideredprofessional judgment that this dilemma has notechnical solution. 3f the great po+ers

continue to loo for solutionsin the area of science and technology only, the result +ill beto

+orsen the situation.2

3 +ould lie to focus your attention not on the sub4ect of the article /national security in anuclear +orld0 but on the indof conclusion they reached, namely that there is no technical

solution to the problem. "n implicit and almost universal assumptionof discussions

published in professional and semipopular scientific

4ournals is that the problem underdiscussion has a technicalsolution. " technical solution may be defined as one that requires

a change only in the techniques of the natural sciences, demandinglittle or nothing in the

+ay of change in human values or ideasof morality.

3n our day /though not in earlier times0 technical solutions are al+ays +elcome. Because ofprevious failures in prophecy,it taes courage to assert that a desired technical solution is

not possible. iesner and -or exhibited this courage; publishingin a science 4ournal, they

insisted that the solution to the problem+as not to be found in the natural sciences. Theycautiously qualifiedtheir statement +ith the phrase, 23t is our considered professional

4udgment... .2 hether they +ere right or not is not the concernof the present article.

5ather, the concern here is +ith the importantconcept of a class of human problems +hich

can be called 2no technicalsolution problems,2 and, more specifically, +ith theidentificationand discussion of one of these.

3t is easy to sho+ that the class is not a null class. 5ecall the game of tic6tac6toe.

Consider the problem, 27o+ can 3+in the game of tic6tac6toe82 3t is +ell no+n that 3cannot,if 3 assume /in eeping +ith the conventions of game theory0 thatmy opponent

understands the game perfectly. ut another +ay, thereis no 2technical solution2 to the

problem. 3 can +in only by givinga radical meaning to the +ord 2+in.2 3 can hit my

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opponent overthe head; or 3 can drug him; or 3 can falsify the records. 9very +ay in +hich 3

2+in2 involves, in some sense, an abandonment ofthe game, as +e intuitively understand it./3 can also, of course,openly abandon the game66refuse to play it. This is +hat most adults

do.0

The class of 2:o technical solution problems2 has members. y thesis is that the2population problem,2 as conventionally conceived,is a member of this class. 7o+ it isconventionally conceivedneeds some comment. 3t is fair to say that most people +ho

anguishover the population problem are trying to find a +ay to avoid the evils of

overpopulation +ithout relinquishing any of the privileges they no+ en4oy. They thin that

farming the seas or developingne+ strains of +heat +ill solve the problem66technologically. 3try to sho+ here that the solution they see cannot be found.The

population problem cannot be solved in a technical +ay, anymore than can the problem of

+inning the game of tic6tac6toe.

What Shall We Maximize?

opulation, as althus said, naturally tends to gro+ 2geometrically,2 or, as +e +ould no+

say, exponentially. 3n a finite+orld this means that the per capita share of the +orld

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+orcalories per person approach as close to =ero as possible. :ogourmet meals, no

vacations, no sports, no music, no literature,no art. ... 3 thin that everyone +ill grant,+ithout argument orproof, that maximi=ing population does not maximi=e goods.

Bentham

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e can mae little progress in +oring to+ard optimum population si=e until +e explicitly

exorci=e the spirit of "dam Smithin the field of practical demography. 3n economic affairs,

TheWealth of Nations/'??)0 populari=ed the 2invisible hand,2 theidea that an individual

+ho 2intends only his o+n gain,2 is, asit +ere, 2led by an invisible hand to promote . . . the

publicinterest2 /%0. "dam Smith did not assert that this +as invariablytrue, and perhaps

neither did any of his follo+ers. But he contributed

to a dominant tendency of thought thathas ever since interfered+ith positive action based on rational analysis, namely, the

tendencyto assume that decisions reached individually +ill, in fact, be the best decisions for

an entire society. 3f this assumption iscorrect it 4ustifies the continuance of our presentpolicy oflaisse=6faire in reproduction. 3f it is correct +e can assumethat men +ill control

their individual fecundity so as to produce the optimum population. 3f the assumption is not

correct, +e needto reexamine our individual freedoms to see +hich 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

setched in a little6no+n pamphlet

/)0 in '*>> by a mathematical amateur named illiam@orster #loyd/'?(6'*%$0. e may +ell call it 2the tragedy of the commons,2using the

+ord 2tragedy2 as the philosopher hitehead used it /?01 2The essence of dramatic tragedy

is not unhappiness. 3tresides in the solemnity of the remorseless +oring of things.27ethen goes on to say, 2This inevitableness of destiny can onlybe illustrated in terms of

human life by incidents +hich in fact involve unhappiness. @or it is only by them that the

futilityof escape can be made evident in the drama.2

The tragedy of the commons develops in this +ay. icture a pasture open to all. 3t is to beexpected that each herdsman +illtry to eep as many cattle as possible on the commons.

Such anarrangement may +or reasonably satisfactorily for centuries becausetribal +ars,

poaching, and disease eep the numbers of both man

and beast +ell belo+ the carryingcapacity of the land. @inally,ho+ever, comes the day of reconing, that is, the day +hen thelong6desired goal of social stability becomes a reality. "t thispoint, the inherent logic of the

commons remorselessly generatestragedy.

"s a rational being, each herdsman sees to maximi=e his gain. 9xplicitly or implicitly,more or less consciously, he ass,2hat is the utility to meof adding one more animal to

my herd82This utility has one negative and one positive component.

'0 The positive component is a function of the increment of one animal. Since the herdsman

receives all the proceeds fromthe sale of the additional animal, the positive utility is nearly

D'.

$0 The negative component is a function of the additional overgra=ing created by one more

animal. Since, ho+ever, the effectsof overgra=ing are shared by all the herdsmen, the

negative utilityfor any particular decision6maing herdsman is only a fraction of '.

"dding together the component partial utilities, the rational herdsman concludes that theonly sensible course for him topursue is to add another animal to his herd. "nd another;

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andanother. . . . But this is the conclusion reached by each andevery rational herdsman

sharing a commons. Therein is the tragedy.9ach man is loced into a system that compelshim to increasehis herd +ithout limit66in a +orld that is limited. 5uin is thedestination

to+ard +hich all men rush, each pursuing his o+n bestinterest in a society that believes in

the freedom of the commons.@reedom in a commons brings ruin to all.

Some +ould say that this is a platitude. ould that it +ereE 3n a sense, it +as learnedthousands of years ago, but natural selection favors the forces of psychological denial /*0.

Theindividual benefits as an individual from his ability to deny the truth even though

society as a +hole, of +hich he is a part,suffers.

9ducation can counteract the natural tendency to do the +rong thing, but the inexorablesuccession of generations requiresthat the basis for this no+ledge be constantly refreshed.

" simple incident that occurred a fe+ years ago in #eominster, assachusetts, sho+s ho+

perishable the no+ledge is. !uringthe Christmas shopping season the paring meters

do+nto+n +ere

covered +ith plastic bags that bore tags reading1 2!o not open

until afterChristmas. @ree paring courtesy of the mayor and city council.2 3n other +ords, facing the

prospect of an increaseddemand for already scarce space. the city fathers reinstitutedthe

system of the commons. /Cynically, +e suspect that they gainedmore votes than they lostby this retrogressive act.0

3n an approximate +ay, the logic of the commons has been understood for a long time,

perhaps since the discovery of agricultureor the invention of private property in real estate.

But it isunderstood mostly only in special cases +hich are not sufficientlygenerali=ed.9ven at this late date, cattlemen leasing nationalland on the +estern ranges demonstrate no

more than an ambivalentunderstanding, in constantly pressuring federal authorities to

increase the head count to the point +here overgra=ing produceserosion and +eed6dominance. #ie+ise, the oceans of the +orldcontinue to suffer from the survival of the

philosophy of thecommons. aritime nations still respond automatically to the shibboleth

of the 2freedom of the seas.2 rofessing to believe in the 2inexhaustibleresources of the

oceans,2 they bring species after species offish and +hales closer to extinction /(0.

The :ational ars present another instance of the +oring out of the tragedy of the

commons. "t present, they are open toall, +ithout limit. The pars themselves are limited

in extent66thereis only one -osemite Falley66+hereas population seems to gro+ +ithout

limit. The values that visitors see in the pars are steadilyeroded. lainly, +e must sooncease to treat the pars as commons or they +ill be of no value to anyone.

hat shall +e do8 e have several options. e might sell them off as private property. e

might eep them as public property,but allocate the right to enter them. The allocationmight beon the basis of +ealth, by the use of an auction system. 3t mightbe on the basis of

merit, as defined by some agreed6upon standards.3t might be by lottery. r it might be on a

first6come, first6servedbasis, administered to long queues. These, 3 thin, are all the

reasonable possibilities. They are all ob4ectionable. But +e mustchoose66or acquiesce in thedestruction of the commons that +ecall our :ational ars.

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Pollution

3n a reverse +ay, the tragedy of the commons reappears in problems of pollution. 7ere it is

not a question of taing something out of the commons, but of putting something in66

se+age, or chemical,radioactive, and heat +astes into +ater; noxious and dangerousfumes

into the air, and distracting and unpleasant advertising

signs into the line of sight. Thecalculations of utility aremuch the same as before. The rational man finds that his share of

the cost of the +astes he discharges into the commons is lessthan the cost of purifying his

+astes before releasing them. Sincethis is true for everyone, +e are loced into a system of2foulingour o+n nest,2 so long as +e behave only as independent, rational,free6

enterprisers.

The tragedy of the commons as a food baset is averted by private property, or something

formally lie it. But the air and+aters surrounding us cannot readily be fenced, and so thetragedyof the commons as a cesspool must be prevented by different means,by coercive

la+s or taxing devices that mae it cheaper for the polluter to treat his pollutants than to

discharge them untreated.

e have not progressed as far +ith the solution of this problem

as+e have +ith the first. 3ndeed, our particular concept of privateproperty, +hich deters us

from exhausting the positive resourcesof the earth, favors pollution. The o+ner of a factory

on theban of a stream66+hose property extends to the middle of the stream,often hasdifficulty seeing +hy it is not his natural right tomuddy the +aters flo+ing past his door.

The la+, al+ays behindthe times, requires elaborate stitching and fitting to adapt it to this

ne+ly perceived aspect of the commons.

The pollution problem is a consequence of population. 3t did not much matter ho+ a lonely"merican frontiersman disposed ofhis +aste. 2@lo+ing +ater purifies itself every

'A miles,2 mygrandfather used to say, and the myth +as near enough to the truth +hen he

+as a boy, for there +ere not too many people. But as

population became denser, the naturalchemical and biologicalrecycling processes became overloaded, calling for a redefinitionofproperty rights.

Ho To !egislate Tem"erance?

"nalysis of the pollution problem as a function of population density uncovers a not

generally recogni=ed principle of morality,namely1 the morality of an act is a function of

the state of thesystem at the time it is performed /'A0. Using the commons asa cesspool

does not harm the general public under frontier conditions,because there is no public, thesame behavior in a metropolisis unbearable. " hundred and fifty years ago a plainsman

could

ill an "merican bison, cut out only the tongue for his dinner,

and discard the rest ofthe animal. 7e +as not in any importantsense being +asteful. Today, +ith only a fe+thousand bison left,+e +ould be appalled at such behavior.

3n passing, it is +orth noting that the morality of an act cannot be determined from a

photograph. ne does not no+ +hethera man illing an elephant or setting fire to the

grassland isharming others until one no+s the total system in +hich his actappears. 2nepicture is +orth a thousand +ords,2 said an ancientChinese; but it may tae 'A,AAA +ords

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to validate it. 3t is astempting to ecologists as it is to reformers in general to try to persuade

others by +ay of the photographic shortcut. But theessense of an argument cannot bephotographed1 it must be presentedrationally66in +ords.

That morality is system6sensitive escaped the attention of most codifiers of ethics in the

past. 2Thou shalt not . . .2 is

the form of traditional ethical directives +hich mae noallo+ancefor particular circumstances. The la+s of our society follo+ thepattern of ancientethics, and therefore are poorly suited to governing a complex, cro+ded, changeable +orld.

ur epicyclicsolution is to augment statutory la+ +ith administrative la+.Since it is

practically impossible to spell out all the conditionsunder +hich it is safe to burn trash in

the bac yard or to runan automobile +ithout smog6control, by la+ +e delegate the details

to bureaus. The result is administrative la+, +hich is rightlyfeared for an ancient reason66

Quis custodiet ipsos custodes8662hoshall +atch the +atchers themselves82 &ohn "dams

said that +emust have 2a government of la+s and not men.2 Bureau administrators,tryingto evaluate the morality of acts in the total system, aresingularly liable to corruption,

producing a government by men,not la+s.

rohibition is easy to legislate /though not necessarily to enforce0; but ho+ do +e legislate

temperance8 9xperience indicatesthat it can be accomplished best through the mediation ofadministrativela+. e limit possibilities unnecessarily if +e suppose that the sentiment of

Quis custodiet denies us the use of administrativela+. e should rather retain the phrase as

a perpetual reminderof fearful dangers +e cannot avoid. The great challenge facing us no+is to invent the corrective feedbacs that are needed toeep custodians honest. e must

find +ays to legitimate the needed authority of both the custodians and the corrective

feedbacs.

Freedom To #reed $s $ntolera%le

The tragedy of the commons is involved in population problems in another +ay. 3n a +orld

governed solely by the principle of 2dog eat dog266if indeed there ever +as such a +orld66ho+ manychildren a family had +ould not be a matter of public concern.arents +ho bred

too exuberantly +ould leave fe+er descendants,not more, because they +ould be unable to

care adequately fortheir children. !avid #ac and others have found that such a negative

feedbac demonstrably controls the fecundity of birds /''0.But men are not birds, and have

not acted lie them for millenniums,at least.

3f each human family +ere dependent only on its o+n resources; if the children of

improvident parents starved to death; if,thus, overbreeding brought its o+n 2punishment2 to

the germ line66then

there +ould be no public interest in controlling the breeding

of families.But our society is deeply committed to the +elfare state /'$0, and hence is confronted +ith

another aspect of thetragedy of the commons.

3n a +elfare state, ho+ shall +e deal +ith the family, the religion, the race, or the class /orindeed any distinguishableand cohesive group0 that adopts overbreeding as a policy to

secureits o+n aggrandi=ement /'>08 To couple the concept of freedomto breed +ith the

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commons to restrainhimself for the general good66by means of his conscience. To mae

such an appeal is to set up a selective system that +ors to+ardthe elimination ofconscience from the race.

Pathogenic 'ffects of Conscience

The long6term disadvantage of an appeal to conscience should be enough to condemn it;but has serious short6term disadvantagesas +ell. 3f +e as a man +ho is exploiting a

commons to desist2in the name of conscience,2 +hat are +e saying to him8 hat doeshe

hear8 66not only at the moment but also in the +ee small hours of the night +hen, half

asleep, he remembers not merely the +ords +e used but also the nonverbal communicationcues +e gave himuna+ares8 Sooner or later, consciously or subconsciously, he sensesthat

he has received t+o communications, and that they are contradictory1 /i0 /intended

communication0 23f you don

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Since proof is difficult, +e may even concede that the results of anxiety may sometimes,

from certain points of vie+, be desirable.The larger question +e should as is +hether, as amatter of policy,+e should ever encourage the use of a technique the tendency /ifnot the

intention0 of +hich is psychologically pathogenic. ehear much tal these days of

responsible parenthood; the coupled+ords are incorporated into the titles of some

organi=ations devoted

to birth control. Some people have proposed massive propaganda

campaigns to instill responsibility into the nation

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compulsorytaxes because +e recogni=e that voluntary taxes +ould favor the

conscienceless. e institute and /grumblingly0 support taxes andother coercive devices toescape the horror of the commons.

"n alternative to the commons need not be perfectly 4ust to be preferable. ith real estate

and other material goods, the

alternative +e have chosen is the institution of privatepropertycoupled +ith legal inheritance. 3s this system perfectly 4ust8"s a geneticallytrained biologist 3 deny that it is. 3t seemsto me that, if there are to be differences in

individual inheritance,legal possession should be perfectly correlated +ith biological

inheritance66that those +ho are biologically more fit to be thecustodians of property and

po+er should legally inherit more.But genetic recombination continually maes a moceryof the doctrineof 2lie father, lie son2 implicit in our la+s of legal inheritance."n idiot

can inherit millions, and a trust fund can eep his estateintact. e must admit that our legal

system of private propertyplus inheritance is un4ust66but +e put up +ith it because +e are

not convinced, at the moment, that anyone has invented a bettersystem. The alternative of

the commons is too horrifying to contemplate. 3n4ustice is preferable to total ruin.

3t is one of the peculiarities of the +arfare bet+een reform and the status quo that it is

thoughtlessly governed by a doublestandard. henever a reform measure is proposed it isoften defeated+hen its opponents triumphantly discover a fla+ in it. "s Gingsley!avis has

pointed out /$'0, +orshippers of the status quo sometimesimply that no reform is possible

+ithout unanimous agreement,an implication contrary to historical fact. "s nearly as 3 can

mae out, automatic re4ection of proposed reforms is based onone of t+o unconscious

assumptions1 /i0 that the status quo isperfect; or /ii0 that the choice +e face is bet+een

reform andno action; if the proposed reform is imperfect, +e presumablyshould tae noaction at all, +hile +e +ait for a perfect proposal.

But +e can never do nothing. That +hich +e have done for thousands of years is also

action. 3t also produces evils. nce +e are a+are that the status quo is action, +e can then

compare itsdiscoverable advantages and disadvantages +ith the predicted advantagesanddisadvantages of the proposed reform, discounting as best +e can for our lac of

experience. n the basis of such a comparison, +e can mae a rational decision +hich +ill

not involve the un+orableassumption that only perfect systems are tolerable.

(ecognition of )ecessity

erhaps the simplest summary of this analysis of man

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Some+hat later +e sa+ that the commons as a place for +aste disposal +ould also have to

be abandoned. 5estrictions on thedisposal of domestic se+age are +idely accepted in theestern+orld; +e are still struggling to close the commons to pollution by automobiles,

factories, insecticide sprayers, fertili=ing operations,and atomic energy installations.

3n a still more embryonic state is our recognition of the evils of the commons in matters ofpleasure. There is almost norestriction on the propagation of sound +aves in the publicmedium.The shopping public is assaulted +ith mindless music, +ithout its consent. ur

government is paying out billions of dollarsto create supersonic transport +hich +ill

disturb %A,AAA peoplefor every one person +ho is +hised from coast to coast > hours

faster. "dvertisers muddy the air+aves of radio and televisionand pollute the vie+ oftravelers. e are a long +ay from outla+ingthe commons in matters of pleasure. 3s this

because our uritaninheritance maes us vie+ pleasure as something of a sin, andpain /that

is, the pollution of advertising0 as the sign of virtue8

9very ne+ enclosure of the commons involves the infringement of somebody

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