While the dogmatist is harmful, the sceptic is useless ...; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or of ignorance. Knowledge is not so precise a concept as is commonly thought. Instead of saying 'I know this', we ought to say 'I more or less know something more or less like this'. ... Knowledge in practical affairs has not the certainty or the precision of arithmetic.

To speak seriously: the standards of "goodness" which are generally recognized by public opinion are not those which are calculated to make the world a happier place. This is due to a variety of causes, of which the chief is tradition, and the next most powerful is the unjust power of dominant classes.

The scientific attitude of mind involves a sweeping away of all other desires in the interest of the desire to know.

There are three ways of securing a society that shall be stable as regards population. The first is that of birth control, the second that of infanticide or really destructive wars, and the third that of general misery except for a powerful minority.

The search for something permanent is one of the deepest of the instincts leading men to philosophy.

More cranks take up unfashionable errors than unfashionable truths.

All serious innovation is only rendered possible by some accident enabling unpopular persons to survive.