The Tragedy of the Commons What Shall We Maximize?

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problems that we must face in the next fewgenerations with the foreseeable technology, it isclear that we will greatly increase human miseryif we do not, during the immediate future,assume that the world available to the terrestrialhuman population is finite. "Space" is no escape.[2]A finite world can support only a finite population;therefore, population growth must eventuallyequal zero. (The case of perpetual widefluctuations above and below zero is a trivialvariant that need not be discussed.) When thiscondition is met, what will be the situation ofmankind? Specifically, can Bentham's goal of"the greatest good for the greatest number" berealized?No -- for two reasons, each sufficient by itself.The first is a theoretical one. It is notmathematically possible to maximize for two (ormore) variables at the same time. This wasclearly stated by von Neumann and Morgenstern,[3] but the principle is implicit in the theory ofpartial differential equations, dating back at leastto D'Alembert (1717-1783).The second reason springs directly frombiological facts. To live, any organism must havea source of energy (for example, food). Thisenergy is utilized for two purposes: meremaintenance and work. For man maintenance oflife requires about 1600 kilocalories a day("maintenance calories"). Anything that he doesover and above merely staying alive will bedefined as work, and is supported by "workcalories" which he takes in. Work calories areused not only for what we call work in commonspeech; they are also required for all forms ofenjoyment, from swimming and automobileracing to playing music and writing poetry. If ourgoal is to maximize population it is obvious whatwe must do: We must make the work calories perperson approach as close to zero as possible.No gourmet meals, no vacations, no sports, nomusic, no literature, no art…I think that everyonewill grant, without argument or proof, thatmaximizing population does not maximize goods.Bentham's goal is impossible.In reaching this conclusion I have made theusual assumption that it is the acquisition ofenergy that is the problem. The appearance ofatomic energy has led some to question thisassumption. However, given an infinite source ofenergy, population growth still produces aninescapable problem. The problem of theacquisition of energy is replaced by the problemof its dissipation, as J. H. Fremlin has so wittilyshown. [4] The arithmetic signs in the analysisare, as it were, reversed; but Bentham's goal isunobtainable.The optimum population is, then, less than themaximum. The difficulty of defining the optimumis enormous; so far as I know, no one hasseriously tackled this problem. Reaching anacceptable and stable solution will surely requiremore than one generation of hard analytical work-- and much persuasion.We want the maximum good per person; butwhat is good? To one person it is wilderness, toanother it is ski lodges for thousands. To one it isestuaries to nourish ducks for hunters to shoot;to another it is factory land. Comparing one goodwith another is, we usually say, impossiblebecause goods are incommensurable.Incommensurables cannot be compared.Theoretically this may be true; but in real lifeincommensurables are commensurable. Only acriterion of judgment and a system of weightingare needed. In nature the criterion is survival. Is itbetter for a species to be small and hideable, orlarge and powerful? Natural selectioncommensurates the incommensurables. Thecompromise achieved depends on a naturalweighting of the values of the variables.Man must imitate this process. There is no doubtthat in fact he already does, but unconsciously. Itis when the hidden decisions are made explicitthat the arguments begin. The problem for theyears ahead is to work out an acceptable theoryof weighting. Synergistic effects, nonlinearvariation, and difficulties in discounting the futuremake the intellectual problem difficult, but not (inprinciple) insoluble.Has any cultural group solved this practicalproblem at the present time, even on an intuitivelevel? One simple fact proves that none has:there is no prosperous population in the world
today that has, and has had for some time, agrowth rate of zero. Any people that hasintuitively identified its optimum point will soonreach it, after which its growth rate becomes andremains zero.Of course, a positive growth rate might be takenas evidence that a population is below itsoptimum. However, by any reasonablestandards, the most rapidly growing populationson earth today are (in general) the mostmiserable. This association (which need not beinvariable) casts doubt on the optimisticassumption that the positive growth rate of apopulation is evidence that it has yet to reach itsoptimum.We can make little progress in working towardoptimum population size until we explicitlyexorcise the spirit of Adam Smith in the field ofpractical demography. In economic affairs, TheWealth of Nations (1776) popularized the"invisible hand," the idea that an individual who"intends only his own gain," is, as it were, "led byan invisible hand to promote…the publicinterest." [5] Adam Smith did not assert that thiswas invariably true, and perhaps neither did anyof his followers. But he contributed to a dominanttendency of thought that has ever sinceinterfered with positive action based on rationalanalysis, namely, the tendency to assume thatdecisions reached individually will, in fact, be thebest decisions for an entire society. If thisassumption is correct it justifies the continuanceof our present policy of laissez faire inreproduction. If it is correct we can assume thatmen will control their individual fecundity so as toproduce the optimum population. If theassumption is not correct, we need to reexamineour individual freedoms to see which ones aredefensible.Tragedy of Freedom in aCommonsThe rebuttal to the invisible hand in populationcontrol is to be found in a scenario first sketchedin a little-known Pamphlet in 1833 by amathematical amateur named William ForsterLloyd (1794-1852). [6] We may well call it "thetragedy of the commons," using the word"tragedy" as the philosopher Whitehead used it[7]: "The essence of dramatic tragedy is notunhappiness. It resides in the solemnity of theremorseless working of things." He then goes onto say, "This inevitableness of destiny can onlybe illustrated in terms of human life by incidentswhich in fact involve unhappiness. For it is onlyby them that the futility of escape can be madeevident in the drama."The tragedy of the commons develops in thisway. Picture a pasture open to all. It is to beexpected that each herdsman will try to keep asmany cattle as possible on the commons. Suchan arrangement may work reasonablysatisfactorily for centuries because tribal wars,poaching, and disease keep the numbers of bothman and beast well below the carrying capacityof the land. Finally, however, comes the day ofreckoning, that is, the day when the long-desiredgoal of social stability becomes a reality. At thispoint, the inherent logic of the commonsremorselessly generates tragedy.As a rational being, each herdsman seeks tomaximize his gain. Explicitly or implicitly, more orless consciously, he asks, "What is the utility tome of adding one more animal to my herd?" Thisutility has one negative and one positivecomponent.1. The positive component is a function of theincrement of one animal. Since the herdsmanreceives all the proceeds from the sale of theadditional animal, the positive utility is nearly + 1.2. The negative component is a function of theadditional overgrazing created by one moreanimal. Since, however, the effects ofovergrazing are shared by all the herdsmen, thenegative utility for any particular decision-makingherdsman is only a fraction of - 1.Adding together the component partial utilities,the rational herdsman concludes that the onlysensible course for him to pursue is to addanother animal to his herd. And another.... Butthis is the conclusion reached by each and everyrational herdsman sharing a commons. Thereinis the tragedy. Each man is locked into a systemthat compels him to increase his herd withoutlimit -- in a world that is limited. Ruin is thedestination toward which all men rush, each
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