Religious reasons, which is no reason. I notice Skeptic had a review of Dennett's book, Darwin's Dangerous Idea. Religious reasons amount to what Dennett terms "skyhooks." Do you believe in skyhooks? I don't.
Garrett HardinNumeracy: 1. The art of putting numbers to things, that is, assigning amounts to variables in order that practical decisions may be reach. 2. That aspect of education (beyond mere literacy) which takes account of quantitative aspects of reality.
Garrett HardinThe 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.
Garrett HardinUsing 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.
Garrett Hardin