“Science is what we have learned about how to keep from fooling ourselves.”

“Science is a way of trying not to fool yourself. The principle is that you must not fool yourself, and you are the easiest person to fool.”

“Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naive, and probably wrong.”

“Philosophy of science is about as useful to scientists as ornithology is to birds.”

“We can't define anything precisely. If we attempt to, we get into the paralysis of thought that comes to philosophers... one saying to the other: you don't know what you are talking about! The second one says: what do you mean by talking? What do you mean by you? What do you mean by know?”

“I don't know what's the matter with people: they don't learn by understanding, they learn by some other way — by rote or something. Their knowledge is so fragile!”

“It was thought in the Middle Ages that people simply make many observations, and the observations themselves suggest the laws. But it does not work that way. It takes much more imagination than that.So the next thing we have to talk about is where the new ideas come from. Actually, it does not make any difference, as long as they come.”