The Tragedy of the Commons 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 de- creasing national security. It is our considered professional judgment that this dilemma has no technical solution. If the great powers continue to look for solutions in the area of science and technology only, the result will be to worsen the situation.” I would like to focus your attention not on the subject of the article (national secu- rity in a nuclear world) but on the kind of conclusion they reached, namely that there is no technical solution to the problem. An implicit and almost universal assumption of discussions published in professional and semipopular scientific journals is that the problem under discussion has a technical solution. A technical solution may be de- fined as one that requires a change only in the techniques of the natural sciences, de- manding 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. Be- cause of previous failures in prophecy, it takes courage to assert that a desired tech- nical solution is not possible. Wiesner and York exhibited this courage; publishing in a science journal, they insisted that the solu- tion to the problem was not to be found in the natural sciences. They cautiously qual- ified their statement with the phrase, “It is our considered professional judgment. . . .” Whether 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 identifica- tion 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 assume (in keep- ing with the conventions of game theory) that my opponent understands the game perfectly. Put another way, there is no “technical solution” 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 aban- donment of the game, as we intuitively understand it. (I can also, of course, open- ly abandon the gamerefuse 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 convention- ally conceived, is a member of this class. How it is conventionally conceived 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 overpopulation without relin- quishing any of the privileges they now enjoy. They think that farming the seas or developing new strains of wheat will solve the problemtechnologically. I try to show here that the solution they seek cannot be found. The population problem cannot be solved in a technical way, any more than can the problem of winning the game of tick-tack-toe. What Shall We Maximize? 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 worlds 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 generations 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 popula- tion is finite. “Space” is no escape (2). 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 situation of mankind? Specifical- ly, can Benthams goal of “the greatest good for the greatest number” be realized? Nofor 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 DAlembert (1717 1783). 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 pur- poses: mere maintenance and work. For man, maint