Indeed the reasoned criticism of a prevailing belief is a service to the proponents of that belief; if they are incapable of defending it, they are well advised to abandon it. This self-questioning and error-correcting aspect of the scientific method is its most striking property.

A millennium before Europeans were willing to divest themselves of the Biblical idea that the world was a few thousand years old, the Mayans were thinking of millions and the Hindus billions.

Widespread intellectual and moral docility may be convenient for leaders in the short term, but it is suicidal for nations in the long term. One of the criteria for national leadership should therefore be a talent for understanding, encouraging, and making constructive use of vigorous criticism.

It's hard to kill a creature once it lets you see its consciousness.

It means nothing to be open to a proposition we don't understand.

I promise to question everything my leaders tell me. I promise to use my critical faculties. I promise to develop my independence of thought. I promise to educate myself so I can make my own judgments.

Scientists constantly get clobbered with the idea that we spent 27 billion dollars on the Apollo programs, and are asked "What more do you want?" We didn't spend it; it was done for political reasons. ... Apollo was a response to the Bay of Pigs fiasco and to the successful orbital flight of Yuri Gagarin. President Kennedy's objective was not to find out the origin of the moon by the end of the decade; rather it was to put a man on the moon and bring him back, and we did that.