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.

Value is a relative concept: the value of each action is determined by comparing it with other possible actions.

Of course, a positive growth rate might be taken as evidence that a population is below its optimum.

The only thing we can really count on in this uncertain world is human unreliability itself.

Indeed, our particular concept of private property, which deters us from exhausting the positive resources of the earth, favors pollution.

An attack on values is inevitably seen as an act of subversion.

(Technology reliability) x (Human reliability) = (System reliability)