When we enter a new situation in life and are confronted by a new person, we bring with us the prejudices of the past and our previous experiences of people. These prejudices we project upon the new person. Indeed, getting to know a person is largely a matter of withdrawing projections; of dispelling the smoke screen of what we imagine he is like and replacing it with the reality of what he is actually like.

There is no history of mankind, there is only an indefinite number of histories of all kinds of aspects of human life.

I am opposed to looking upon logic as a kind of game. ... One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.

You cannot have a rational discussion with a man who prefers shooting you to being convinced by you.

It is part of my thesis that all our knowledge grows only through the correcting of our mistakes.

Science does not rest upon solid bedrock. The bold structure of its theories rises, as it were, above a swamp. It is like a building erected on piles. The piles are driven down from above into the swamp, but not down to any natural or 'given' base; and if we stop driving the piles deeper, it is not because we have reached firm ground. We simply stop when we are satisfied that the piles are firm enough to carry the structure, at least for the time being.

Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.