What Shanl We Mam ? 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 The population problem has no technical solution ; that we do not know that it is not . But , it requires a fundamental extension in morality . in terms of the practical problems that we must face in the next few generations with the foreseeable technology , it Garrett Hardin 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 popAt the end of a thoughtful article on sional judgment ... '' Vhether they ulation is finite . `` Space '' is no escape the future of nuclear war , Wiesner and were right or not is not the concern of -LRB- 2 -RRB- . A finite world can support only a York -LRB- 1 -RRB- concluded that : `` Both sides in the present article . Rather , the concern the arms race are ... confronted by the here is with the important concept of a finite population ; therefore , population dilemma of steadily increasing military class of human problems which can be growth must eventually equal zero . -LRB- The power and steadily decreasing national called `` no technical solution problems , '' case of perpetual wide fluctuations security . It is our considered profes - and , more specifically , with the identifi - above and below zero is a trivial variant sional judgment that this dilemma has cation and discussion of one of these . that need not be discussed . -RRB- When this no technical solution . If the great powIt is easy to show that the class is not condition is met , what will be the situaers continue to look for solutions in a null class . Recall the game of tick - tion of mankind ? Specifically , can Benthe area of science and technology only , tack-toe . Consider the problem , `` How tham 's goal of `` the greatest good for the result will be to worsen the situa - can I win . the game of tick-tack-toe ? '' the greatest number '' be realized ? tion . '' It is well known that I can not , if I asNo-for two reasons , each sufficient I would like to focus your attention sume -LRB- in keeping with the conventions by itself . The first is a theoretical one . not on the subject of the article -LRB- na - of game theory -RRB- that my opponent un - It is not mathematically possible to tional security in a nuclear world -RRB- but derstands the game perfectly . Put an - maximize for two -LRB- or more -RRB- variables at on the kind of conclusion they reached , other way , there is no `` technical solu - the same time . This was clearly stated namely that there is no technical solu - tion '' to the problem . I can win only by von Neumann and Morgenstern -LRB- 3 -RRB- , tion to the problem . An implicit and by giving a radical meaning to the word but the principle is implicit in the theory almost universal assumption of discus - `` win . '' I can hit my opponent over the of partial differential equations , dating sions published in professional and head ; or I can drug him ; or I can falsify back at least to D'Alembert -LRB- 1717semipopular scientific journals is that the records . Every way in which I `` win '' 1783 -RRB- . the problem under discussion has a involves , in some sense , an abandonThe second reason springs directly technical solution . A technical solution ment of the game , as we intuitively un - from biological facts . To live , any may be defined as one that requires a derstand it . -LRB- I can also , of course , organism must have a source of energy change only in . the techniques of the openly abandon the game-refuse to -LRB- for example , food -RRB- . This energy is natural sciences , demanding little or play it . This is what most adults do . -RRB- utilized for two puposes : mere mainnothing in the way of change in human The class of `` No technical solution tenance and work . For man , maintevalues or ideas of morality . problems '' has members . My thesis is nance of life requires about 1600 kiloIn our day -LRB- though not in earlier that the `` population problem , '' as con - calories a day -LRB- `` maintenance calories ' -RRB- . times -RRB- technical solutions are always ventionally conceived , is a member of Anything that he does over and above welcome . Because of previous failures this class . How it is conventionally con - merely staying alive will be defined as in prophecy , it takes courage to assert ceived needs some comment . It is fair work , and is supported by `` work calthat a desired technical solution is not to say that most people who ' anguish ories '' which he takes in . Work calories possible . Wiesner and York exhibited over the population problem are trying are used not only for what we call work this courage ; publishing in a science to find a way to avoid the evils of over - in common speech ; they are also rejournal , they insisted that the solution population without relinquishing any of quired for all forms of enjoyment , from to the problem was not to be found in the privileges they now enjoy . They swimming and automobile racing to the natural sciences . They cautiously think that farming the seas or develop - playing music and writing poetry . If qualified their statement with the ing new strains of wheat will solve the our goal is to maximize population it is phrase , `` It is our considered profes - problem-technologically . I try to show obvious what we must do : We must here that the solution they seek can not make the work calories per person apThe author is professor of biology , University of California , Santa Barbara . This article is be found . The population problem can - proach as close to zero as possible . No based on a presidential address presented before not be solved in a technical way , any gourmet meals , no vacations , no sports , the meeting of the Pacific Division of the Amerimore than can the problem of winning no music , no literature , no art ... . I can Association for the Advancement of Science at Utah State University , Logan , 25 June 1968 . the game of tick-tack-toe . think that everyone will grant , without The Tragedy of the Commons 13 DECEMBER 1968 1243 time,-p - rate of zero . Any people that has intuitively identified its optimum point will soon reach it , after which its growth rate becomes and remains zero . Of course , a positive growth rate might be taken as evidence that a population is below its optimum . However , assumption . However , given an infinite by any reasonable standards , the most source of energy , population growth rapidly growing populations on earth still produces an inescapable problem . today are -LRB- in general -RRB- the most miseraThe problem of the acquisition of en - ble . This association -LRB- which need not be ergy is replaced by the problem of its invariable -RRB- casts doubt on the optimistic dissipation , as J. H. Fremlin has so wit - assumption that the positive growth rate tily shown -LRB- 4 -RRB- . The arithmetic signs in of a population is evidence that it has - t-he analysis are , as it were , reversed ; yet to reach its optimum . but Bentham 's goal is still unobtainable . We can make little progress in workThe optimum population is , then , less ing toward optimum poulation size until than the maximum . The difficulty of we explicitly exorcize the spirit of defining the optimum is enormous ; so Adam Smith in the field of practical far as I know , no one has seriously demography . In economic affairs , The tackled this problem . Reaching an ac - Wealth of Nations -LRB- 1776 -RRB- popularized ceptable and stable solution will surely the `` invisible hand , '' the idea that an require more than one generation of individual who `` intends only his own hard analytical work-and much per - gain , '' is , as it were , `` led by an invisible hand to promote . . , . the public interest '' suasion . We want the maximum good per -LRB- 5 -RRB- . Adam Smith did not assert that person ; but what is good ? To one per - this was invariably true , and perhaps son it is wilderness , to another it is ski neither did any of his followers . But he lodges for thousands . To one it is estu - contributed to a dominant tendency of aries to nourish ducks for hunters to thought that has ever since interfered shoot ; to another it is factory land . with positive action based on rational Comparing one good with another is , analysis , namely , the tendency to aswe usually say , impossible because sume that decisions reached individually goods are incommensurable . Incommen - will , in fact , be the best decisions for an entire society . If this assumption is surables can not be compared . Theoretically this may be true ; but in correct it justifies the continuance of real life incommensurables are commen - our present policy of laissez-faire in surable . Only a criterion of judgment reproduction . If it is correct we can asand a system of weighting are needed . sume that men will control their individIn nature the criterion is survival . Is it ual fecundity so as to produce the optibetter for a species to be small and hide - mum population . If the assumption is able , or large and powerful ? Natural not correct , we need to reexamine our selection commensurates the incommen - individual freedoms to see which ones surables . The compromise achieved de - are defensible . pends on a natural weighting of the values of the variables . Man must imitate this process . There Tragedy of Freedom in a Commons is no doubt that in fact he already does , The rebuttal to the invisible hand in but unconsciously . It is when the hidden decisions are made explicit that the population control is to be found in a arguments begin . The problem for the scenario first sketched in a little-known years ahead is to work out an accept - pamphlet -LRB- 6 -RRB- in 1833 by a mathematical able theory of weighting . Synergistic amateur named William Forster Lloyd effects , nonlinear variation , and difficul - -LRB- 1794-1852 -RRB- . We may well call it `` the ties in discounting the future make the tragedy of the commons , '' using the intellectual problem difficult , but not word `` tragedy '' as the philosopher Whitehead used it -LRB- 7 -RRB- : `` The essence of -LRB- in principle -RRB- insoluble . Has any cultural group solved this dramatic tragedy is not unhappiness . It practical problem at the present time , resides in the solemnity of the remorseeven on an intuitive level ? One simple less working of things . '' He then ' goes on . fact proves that none has : there is no to say , `` This inevitableness of destiny prosperous population in the world to - can only be illustrated in terms of huday that has , and has had for some man life by incidents which in fact in1244 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 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 herdsman will try to keep as many cattle as possible on the commons . Such an arrangement may work reasonably satisfactorily 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 becomes a reality . At this point , the inherent logic of the commons remorselessly 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 . 1 -RRB- The positive component is a function 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 -RRB- The negative component is a function 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 decisionmaking herdsman is only a fraction of -1 . Adding together the component partial 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 toward which all men rush , each pursuing his own best interest in a society that believes in the freedom of the commons . Freedom in a commons brings ruin to all . Some would say that this is a platitude . Would that it were ! In a sense , it was learned thousands of years ago , but natural selection favors the forces of psychological denial -LRB- 8 -RRB- . 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 Education can counteract the natural tendency to do the wrong thing , but the inexorable succession of generations requires that the basis for this knowledge be constantly refreshed . A simple incident that occurred a few years ago in Leominster , Massachusetts , shows how perishable the knowledge is . During the Christmas shopping season the parking meters downtown were covered with plastic bags that bore tags reading : `` Do not open until after Christmas . Free parking courtesy of the mayor and city council . '' In other words , facing the prospect of an increased demand for already scarce space , the city fathers reinstituted the system of the commons . -LRB- Cynically , we suspect that they gained more votes than they lost by this retrogressive act . -RRB- In an approximate way , the logic of the commons has been understood for a long time , perhaps since the discovery of agriculture or the invention of private property in real estate . But it is understood mostly only in special cases which are not sufficiently generalized . Even at this late date , cattlemen leasing national land on the western ranges demonstrate no more than an ambivalent understanding , in constantly pressuring federal authorities to increase the head count to the point where overgrazing produces erosion and weeddominance . Likewise , the oceans of the world continue to suffer from the survival of the philosophy of the commons . Maritime nations still respond automatically to the shibboleth of the `` freedom of the seas . '' Professing to believe in the `` inexhaustible resources of the oceans , '' they bring species after species of fish and whales closer to extinction upon standards . It might be by lottery . Or it might be on a first-come , firstserved basis , administered to long queues . These , I think , are all the reasonable possibilities . They are all objectionable . But we must choose-or acquiesce in the destruction of the commons that we call our National Parks . Pollution In a reverse way , the tragedy of the commons reappears in problems of pollution . Here it is not a question of taking something out of the commons , but of putting something in-sewage , or chemical , radioactive , and heat wastes into water ; noxious and dangerous fumes into the air ; and distracting and unpleasant advertising signs into the line of sight . The calculations of utility are much the same as before . The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them . Since this is true for everyone , we are locked into a system of `` fouling our own nest , '' so long as we behave only as independent , rational , free-enterprisers . The tragedy of the commons as a food basket is averted by private property , or something formally like it . But the air and waters surrounding us can not readily be fenced , and so the tragedy of the commons as a cesspool must be prevented by different means , by coercive laws or taxing devices that make it cheaper for the polluter to treat his pollutants than to discharge them untreated . We have not progressed as far with the solution of this problem as we have with the first . Indeed , our particular concept of private property , which deters us from exhausting the positive resources of the earth , favors pollution . The owner of a factory on the bank of a stream-whose property extends to the middle of the stream-often has difficulty seeing why it is not his natural right to muddy the waters flowing past his door . The law , always behind the times , requires elaborate stitching and fitting to adapt it to this newly perceived aspect of the commons . The pollution problem is a consequence of population . It did not much matter how a lonely American frontiersman disposed of his waste . `` Flowing water purifies itself every 10 miles , '' my grandfather used to say , and the myth was near enough to the truth when he was a boy , for there were not too many people . But as population became denser , the natural chemical and biological recycling processes became overloaded , calling for a redefinition of property rights . How To Legislate Temperance ? Analysis of an act of the pollution problem as a function of population density uncovers a not generally recognized prin - ciple of morality , namely : is a function the morality -LRB- 9 -RRB- . The National Parks present another instance of the working out of the tragedy of the commons . At present , they are open to all , without limit . The parks themselves are limited in extentthere is only one Yosemite Valleywhereas population seems to grow without limit . The values that visitors seek in the parks are steadily eroded . Plainly , we must soon cease to treat the parks as commons or they will be of no value to anyone . What shall we do ? We have several options . We might sell them off as private property . We might keep them as public property , but allocate the right to enter them . The allocation might be on the basis of wealth , by the use of an auction system . It might be on the basis of merit , as defined by some agreed13 DECEMBER 1968 others until one knows the total system in which his act appears . `` One picture is worth a thousand words , '' said an ancient Chinese ; but it may take 10,000 words to validate it . It is as tempting to ecologists as it is to reformers in general to try to persuade others by way of the photographic shortcut . But the essense of an argument can not be photographed : it must be presented rationally - in words . That morality is system-sensitive escaped the attention of most codifiers of ethics in the past . `` Thou shalt not ... '' is the form of traditional ethical directives which make no allowance for particular circumstances . The laws of our society follow the pattern of ancient ethics , and therefore are poorly suited to governing a complex , crowded , changeable world . Our epicyclic solution is to augment statutory law with administrative law . Since it is practically impossible to spell out all the conditions under which it is safe to burn trash in the back yard or to run an automobile without smog-control , by law we delegate the details to bureaus . The result is administrative law , which is rightly feared for an ancient reason-Quis custodiet ipsos custodes ? - `` Who shall 1245 of the state of the system at the time it is performed -LRB- 10 -RRB- . Using the commons as a cesspool does not harm the general public under frontier conditions , because there is no public ; the same behavior in a metropolis is unbearable . A hundred and fifty years ago a plainsman could kill an American bison , cut out only the tongue for his dinner , and discard the rest of the animal . He was not in any important sense being wasteful . Today , with only a few thousand bison left , we would be appalled at such behavior . In passing , it is worth noting that the morality of an act can not be determined from a photograph . One does not know whether a man killing an elephant or setting flre to the grassland is harming - A watch the watchers themselves ? '' John Adams said that we must have `` a government of laws and not men . '' Bureau administrators , trying to evaluate the morality of acts in the total system , are singularly liable to corruption , producing a government by men , not laws . Prohibition is easy to legislate -LRB- though not necessarily to enforce -RRB- ; but how do we legislate temperance ? Experience indicates that it can be accomplished best through the mediation of administrative law . We limit possibilities 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 can not avoid . The great challenge facing us now is to invent the corrective feedbacks that are needed to keep custodians honest . We must find ways to legitimate the needed authority of both the custodians and the corrective feedbacks . 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 -LRB- 14 -RRB- : The Universal Declaration of Human Rights describes the family as the natural and fundamental unit of society . It follows that any choice and decision with regard to the size of the family must irtevocably rest with the family itself , and can not be made by anyone else . It is painful to have to deny categorically the validity of this right ; denying it , one feels as uncomfortable as a resident 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 should n't find fault with it ; we should n't play into the hands of the archconservatives . However , let us not forget what Robert Louis Stevenson said : `` The truth that is suppressed by Freedom To Breed Is Intolerable friends is the readiest weapon of the enemy . '' If truth we must The tragedy of the commons is in - openly deny we love theof the Universal the validity volved in population problems in anRights , other way . In a world governed solely Declarationis of Human by the even though it promoted by the principle of `` dog eat dog '' - if Nations . We should also joinUnited with indeed there ever was such a world - Kingsley Davis -LRB- 15 -RRB- in attempting to how many children a family had would get Planned Parenthood-World Populanot be a matter of public concern . tion to see the error of its ways in emParents who bred too exuberantly would bracing the same tragic ideal . leave fewer descendants , not more , because they would be unable to care adequately for their children . David Conscience Is Self-Eliminating Lack and others have found that such a negative feedback demonstrably conIt is a mistake to think that we can trols the fecundity of birds -LRB- 11 -RRB- . But control the breeding of mankind in the men are not birds , and have not acted long run by an appeal to conscience . like them for millenniums , at least . Charles Galton Darwin made this point If each human family were depen - when he spoke on the centennial of the dent only on its own resources ; if the publication of his grandfather 's great children of improvident parents starved book . The argument is straightforward to death ; if , thus , overbreeding brought and Darwinian . its own `` punishment '' to the germ linePeople vary . Confronted with appeals then there would be no public interest to limit breeding , some people will unin controlling the breeding of families . doubtedly respond to the plea more But our society is deeply committed to than others . Those who have more the welfare state -LRB- 12 -RRB- , and hence is children will produce a larger fraction confronted with another aspect of the of the next generation than those with more susceptible consciences . The diftragedy of the commons . In a welfare state , how shall we deal ference will be accentuated , generation with the family , the religion , the race , by generation . In C. G. Darwin 's words : `` It may or the class -LRB- or indeed any distinguishable and cohesive group -RRB- that adopts well be that it would take hundreds of overbreeding as a policy to secure its generations for the progenitive instinct own aggrandizement -LRB- 13 -RRB- ? To couple to develop in this way , but if it should the concept of freedom to breed with do so , nature would have taken her the belief that everyone born has an revenge , and the variety Homo contra1246 cipiens would become extinct and would be replaced by the variety Homo progenitivus '' -LRB- 16 -RRB- . The argument assumes that conscience or the desire for children -LRB- no matter which -RRB- is hereditary-but hereditary 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 . -LRB- If one denies the latter possibility as well as the former , then what 's the point of education ? -RRB- 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 shortterm 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 communications , and that they are contradictory : -LRB- i -RRB- -LRB- intended communication -RRB- `` If you do n't do as we ask , we will openly condemn you for not acting like a responsible citizen '' ; -LRB- ii -RRB- -LRB- the unintended communication -RRB- `` 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 -LRB- 17 -RRB- . 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 moderate 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 feelings 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 themselves , and not even to their own interests , which might make sense , but to their anxieties '' -LRB- 18 -RRB- . One does not have to be a professional psychiatrist to see the consequences 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 prohibition laws , but perhaps more effectively by the anxiety-generating mechanisms of education . Alex Comfort has told the story well in The Anxiety Makers -LRB- 19 -RRB- ; 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 -LRB- if not the intention -RRB- of which is psychologically pathogenic . We hear much talk these days of responsible parenthood ; the coupled words are incorporated into the titles of some organizations devoted to birth control . Some people have proposed massive propaganda campaigns to instill responsibility into the nation 's -LRB- or the world 's -RRB- breeders . But what is the meaning of the word responsibility in this context ? Is it not merely a synonym for the word conscience ? When we use the word responsibility 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 -LRB- 20 -RRB- . `` Responsibility , '' says this philosopher , `` is the product of definite social arrangements . '' Notice that Frankel calls for social arrangements-not propa - coercion is not to say that we are re - ganda . Mutual Coercion 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 -LRB- grumblingly -RRB- support taxes and other coercive devices to escape the horror of the commons . Mutually Agreed upon The social arrangements that produce responsibility are arrangements that create coercion , of some sort . Consider 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 freedom 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 Madison Avenue man might call this persuasion ; 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 exposure to the light , by saying it over and over without apology or embarrassment . To many , the word coercion implies arbitrary decisions of distant and irresponsible 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 An alternative to the commons need 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 differences in individual inheritance , legal possession should be perfectly correlated 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 inheritance . 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 inheritance 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 contemplate . Injustice is preferable to total not be 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 reform measure is proposed it is often defeated when its opponents triumphantly discover a flaw in it . As Kingsley Davis has pointed out -LRB- 21 -RRB- , worshippers of the status quo sometimes imply that no reform is possible without unanimous agreement , an implication contrary to historical fact . As nearly as I can make out , automatic rejection of proposed reforms is based on one of two unconscious assumptions : -LRB- i -RRB- that the status quo is perfect ; or -LRB- ii -RRB- 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 1247 status quo is action , we can then compare its discoverable advantages and disadvantages with the predicted advantages and disadvantages of the proposed reform , discounting as best we can for our lack of experience . On the basis of such a comparison , we can make a rational decision which will not involve the unworkable assumption that only perfect systems are tolerable . government is paying out billions of dollars to create supersonic transport which will disturb 50,000 people for every one person who is whisked from coast to coast 3 hours faster . Advertisers muddy the airwaves of radio and television and pollute the view of travelers . We are a long way from outlawing the commons in matters of pleasure . Is this because our Puritan inheritance makes us view pleasure as something of a sin , and pain -LRB- that is , Recognition of Necessity the pollution of advertising -RRB- as the sign of virtue ? Perhaps the simplest summary of this Every new enclosure of the comanalysis of man 's population problems mons involves the infringement of is this : the commons , if justifiable at somebody 's personal liberty . Infringeall , is justifiable only under conditions ments made in the distant past are acof low-population density . As the hu - cepted because no contemporary comman population has increased , the plains of a loss . It is the newly procommons has had to be abandoned in posed infringements that we vigorously oppose ; cries of `` rights '' and `` freedom '' one aspect after another . First we abandoned the commons in fill the air . But what does `` freedom '' food gathering , enclosing farm land mean ? When men mutually agreed to and restricting pastures and hunting pass laws against robbing , mankind beand fishing areas . These restrictions came more free , not less so . Individuals are still not complete throughout the locked into the logic of the commons are free only to bring on universal ruin ; world . Somewhat later we saw that the com - once they see the necessity of mutual mons as a place for waste disposal coercion , they become free to pursue would also have to be abandoned . Re - other goals . I believe it was Hegel who strictions on the disposal of domestic said , `` Freedom is the recognition of sewage are widely accepted in the necessity . '' The most important aspect of necesWestern world ; we are still struggling to close the commons to pollution by sity that we must now recognize , is the automobiles , factories , insecticide necessity of abandoning the commons sprayers , fertilizing operations , and in breeding . No technical solution can rescue us from the misery of overpopuatomic energy installations . In a still more embryonic state is our lation . Freedom to breed will bring recognition of the evils of the commons ruin to all . At the moment , to avoid in matters of pleasure . There is almost hard decisions many of us are tempted no restriction on the propagation of to propagandize for conscience and sound waves in the public medium . The responsible parenthood . The temptashopping public is assaulted with mind - tion must be resisted , because an apless music , without its consent . Our peal to independently acting con - sciences selects for the disappearance of all conscience in the long run , and anin , crease in anxiety in the short . The only way we can preserve and nurture other and more precious freedoms is by relinquishing the freedom to breed , and that very soon . `` Freedom is the recognition of necessity '' - and it is the role of education to reveal to all the necessity of abandoning the freedom to breed . Only so , can we put an end to this aspect of the tragedy of the commons . References 1 . J. B. Wiesner and H. F. York , Sci . Amer . 211 -LRB- No. 4 -RRB- , 27 -LRB- 1964 -RRB- . 2 . G. Hardin , J. Hered . 50 , 68 -LRB- 1959 -RRB- ; S. von Hoernor , Science 137 , 18 -LRB- 1962 -RRB- . 3 . J. von Neumann and 0 . Morgenstern , Theory of Games and Economic Behavior -LRB- Princeton Univ. . Press , Princeton , N.J. , 1947 -RRB- , p. 11 . 4 . J. H. Fremlin , New Sci. , No. 415 -LRB- 1964 -RRB- , p. 285 . 5 . A. Smith , The Wealth of Nations -LRB- Modem Library , New York , 1937 -RRB- , p. 423 . 6 . W. F. Lloyd , Two Lectures on the Checks to Population -LRB- Oxford Univ. . Press , Oxford , England , 1833 -RRB- , reprinted -LRB- in part > in Population , Evolution , and Birth Control , G. Hardin , Ed . -LRB- Freeman , San Francisco , 1964 -RRB- , p. 37 . 7 . A. N. Whitehead , Science and the Modern World -LRB- Mentor , New York , 1948 -RRB- , p. 17 . 8 . G. Hardin , Ed . Population , Evolution , and Birth Control -LRB- Freeman , San Francisco , 1964 -RRB- , p. 56 . 9 . S. McVay , Sci . Amer . 216 -LRB- No. 8 > , 13 -LRB- 1966 -RRB- . 10 . J. Fletcher , Situation Ethics -LRB- Westminster , 11 . D. Lack , The Natural Regulation of Animal Philadelphia , 1966 -RRB- . Nuimbers -LRB- Clarendon Press , Oxford , 1954 -RRB- . 12 . H. Girvetz , From Wealth to Welfare -LRB- Stanford Univ. . Press , Stanford , Calif. , 1950 -RRB- . 13 . G. Hardin , Perspec . Biol . Med . 6 , 366 -LRB- 1963 -RRB- . 14 . U. Thant , Int . Planned Parenthood News , No. 168 -LRB- February 1968 > , p. 3 . 15 . K. Davis , Science 158 , 730 -LRB- 1967 -RRB- . 16 . S. Tax , Ed. , Evolution after Darwin -LRB- Univ. of Chicago Press , Chicago , 1960 -RRB- , vol . 2 , p. 469 . 17 . G. Bateson , D. D. Jackson , J. Haley , J. Weakland , Behav . Scd . 1 , 251 -LRB- 1956 -RRB- . 18 . P. Goodman , New York Rev. Books 10 -LRB- 8 -RRB- , 22 -LRB- 23 May 1968 -RRB- . 19 . A. Comfort , The Anxiety Makers -LRB- Nelson , London , 1967 -RRB- . 20 . C. Frankel , The Case for Modern Man -LRB- Harper , New York , 1955 -RRB- , p. 203 . 21 . J. D. Roslansky , Genetics and the Future of Man -LRB- Appleton-Century-Crofts , New York , 1966 -RRB- , p. 177 . 1248 SCIENCE , VOL . 162

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

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