Rationalism is an attitude of readiness to listen to contrary arguments and to learn from experience... of admitting that "I may be wrong and you may be right and, by an effort, we may get nearer the truth."

A rationalist is simply someone for whom it is more important to learn than to be proved right; someone who is willing to learn from others - not by simply taking over another's opinions, but by gladly allowing others to criticize his ideas and by gladly criticizing the ideas of others

What really makes science grow is new ideas, including false ideas.

Every solution of a problem raises new unsolved problems.

I remained a socialist for several years, even after my rejection of Marxism; and if there could be such a thing as socialism combined with individual liberty, I would be a socialist still. For nothing could be better than living a modest, simple, and free life in an egalitarian society.

The only way to test a hypothesis is to look for all the information that disagrees with it.

[To] interpret Parmenides as a Kant before Kant ... this is exactly what we must do.