Behavior is shaped and maintained by its consequences

Better contraceptives will control population only if people will use them. A nuclear holocaust can be prevented only if the conditions under which nations make war can be changed. The environment will continue to deteriorate until pollution practices are abandoned. We need to make vast changes in human behavior.

...not everyone is willing to defend a position of 'not knowing.' There is no virtue in ignorance for its own sake.

Any single historical event is too complex to be adequately known by anyone. It transcends all the intellectual capacities of men. Our practice is to wait until a sufficient number of details have been forgotten. Of course things seem simpler then! Our memories work that way; we retain the facts which are easiest to think about.

I've often said that my rats have taught me much more than I've taught them.

I don't believe in God, so I'm not afraid of dying.

Twenty-five hundred years ago it might have been said that man understood himself as well as any other part of the world. Today he is the thing he understands least.