It is not possible to write clearly enough to avoid being misrepresented by people who are sufficiently determined to do so.

A rationalist, as I use the word, is a man who attempts to reach decisions by argument and perhaps, in certain cases, by compromise, rather than by violence. He is a man who would rather be unsuccessful in convincing another man by argument than successful in crushing him by force, by intimidation and threats, or even by persuasive propaganda.

I see now more clearly than ever before that even our greatest troubles spring from something that is [as] admirable and sound as it is dangerous – from our impatience to better the lot of our fellows.

We must plan for freedom, and not only for security, if for no other reason than only freedom can make security more secure.

The conspiracy theory of society... comes from abandoning god and then asking: "Who is in his place"

The growth of our knowledge is the result of a process closely resembling what Darwin called 'natural selection'; that is, the natural selection of hypotheses: our knowledge consists, at every moment, of those hypotheses which have shown their (comparative) fitness by surviving so far in their struggle for existence, a competitive struggle which eliminates those hypotheses which are unfit.

Science is perhaps the only human activity in which errors are systematically criticized and, in time, corrected.