Behavior is shaped and maintained by its consequences

I may say that the only differences I expect to see revealed between the behavior of the rat and man (aside from enormous differences of complexity) lie in the field of verbal behavior.

A fourth-grade reader may be a sixth-grade mathematician. The grade is an administrative device which does violence to the nature of the developmental process.

The major difference between rats and people is that rats learn from experience.

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.

Science, not religion, has taught me my most useful values, among them intellectual honesty. It is better to go without answers than to accept those that merely resolve puzzlement.

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