Karl Popper Quotes

125 Sourced Quotes

The genuine rationalist does not think that he or anyone else is in possession of the truth; nor does he think that mere criticism as such helps us achieve new ideas. But he does think that, in the sphere of ideas, only critical discussion can help us sort the wheat from the chaff.

Karl Popper
Only a man who understands science (that is scientific problems) can understand its history... Only a man who has some real understanding of its history (the history of its problem situations) can understand science.

Karl Popper
Every discovery contains an irrational element or a creative intuition.

Karl Popper
As with our children, so with our theories, and ultimately with all the work we do: our products become largely independent of their makers. We may gain more knowledge from our children or from our theories than we ever imparted to them.

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

Karl Popper
If you know that things are bound to happen whatever you do, then you may feel free to give up the fight against them.

Karl Popper
The quest for precision is analogous to the quest for certainty and both - precision and certainty are impossible to attain.

Karl Popper
We have no reason to regard the new theory as better than the old theory — to believe that it is nearer to the truth — until we have derived from the new theory new predictions which were unobtainable from the old theory (the phases of Venus.) and until we have found that these new predictions were successful.

Karl Popper
It is the rule which says that the other rules of scientific procedure must be designed in such a way that they do not protect any statement in science against falsification.

Karl Popper
The use of violence is justified only under a tyranny which makes reforms without violence impossible, and should have only one aim, that is, to bring about a state of affairs which makes reforms without violence possible.

Karl Popper
All science and all philosophy are enlightened common sense.

Karl Popper
It is not intuitive ease I am after, but rather a point of view which is sufficiently definite to clear up some difficulties, and to be criticized in rational terms. (Bohr's complementarity cannot be so criticized, I fear; it can only be accepted or denounced - perhaps as being ad hoc, or as being irrational, or as being hopelessly vague.)

Karl Popper
I am inclined to think that scientific discovery is impossible without faith in ideas which are of a purely speculative kind, and sometimes even quite hazy; a faith which is completely unwarranted from the point of view of science...

Karl Popper
Genuine philosophical problems are always rooted outside philosophy and they die if these roots decay.

Karl Popper
Science does not aim, primarily, at high probabilities. It aims at a high informative content, well backed by experience. But a hypothesis may be very probable simply because it tells us nothing, or very little.

Karl Popper
What is to be called "science" and who is to be called a "scientist" must always remain a matter of convention or decision.

Karl Popper
I have insisted that we must be tolerant. But I also believe that this tolerance has its limits. We must not trust those anti-humanitarian religions which not only preach destruction but act accordingly. For if we tolerate them, then we become ourselves responsible for for their deeds.

Karl Popper
Now this principle of induction cannot be a purely logical truth like a tautology or an analytic statement....

Karl Popper
Historically speaking all - or very nearly all - scientific theories originate from myths.

Karl Popper
Never let yourself be goaded into taking seriously problems about words and their meanings. What must be taken seriously are questions of fact, and assertions about facts: theories and hypotheses; the problems they solve; and the problems they raise.

Karl Popper
Whenever we propose a solution to a problem, we ought to try as hard as we can to overthrow our solution, rather than defend it.

Karl Popper
The activity of understanding is, essentially, the same as that of all problem solving.

Karl Popper
Serious rational criticism is so rare that it should be encouraged. Being too ready to defend oneself is more dangerous than being too ready to admit a mistake.

Karl Popper
From the amoeba to Einstein, the growth of knowledge is always the same: we try to solve our problems, and to obtain, by a process of elimination, something approaching adequacy in our tentative solutions.

Karl Popper
We should have to represent the tree of knowledge as springing from countless roots which grow up into the air rather than down, and which ultimately, high up, tend to unite into one common stem.

Karl Popper
Science never pursues the illusory aim of making its answers final or even probable. Its advance is rather toward an infinite yet attainable aim: that of ever discovering new, deeper, and more general problems.

Karl Popper
Is the world ruled by strict laws or not? This question I regard as metaphysical. The laws we find are always hypotheses; which means that they may always be superseded, and that they may possibly be deduced from probability estimates. Yet denying causality would be the same as attempting to persuade the theorist to give up his search; and that such an attempt cannot be backed by anything like a proof...

Karl Popper
The relationship between a theory (or a statement) and the words used in its formulation is in several ways analogous to that between written words and the letters used in writing them down.

Karl Popper
In order that a new theory should constitute a discovery or a step forward it should conflict with its predecessor... it should contradict its predecessor; it should overthrow it. In this sense, progress in science — or at least a striking progress — is always revolutionary.

Karl Popper
But some of these theories are so bold that they can clash with reality: they are the testable theories of science. And when they clash, then we know that there is a reality; something that can inform us that our ideas are mistaken.

Karl Popper