Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society, then the tolerant will be destroyed, and tolerance with them. We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.— Karl Popper
The most pleasurable Karl Popper quotes that will transform you to a better person
I remained a socialist for several years, even after my rejection of Marxism;
and if there could be such a thing as socialism combined with individual liberty, I would be a socialist still. For nothing could be better than living a modest, simple, and free life in an egalitarian society.
True ignorance is not the absence of knowledge, but the refusal to acquire it.
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.
The growth of knowledge depends entirely upon disagreement.
No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.
The best thing that can happen to a human being us to find a problem, to fall in love with that problem, and to live trying to solve that problem, unless another problem even more lovable appears.
The war of ideas is a Greek invention.
It is one of the most important inventions ever made. Indeed, the possibility of fighting with with words and ideas instead of fighting with swords is the very basis of our civilization, and especially of all its legal and parliamentary institutions.
Ignorance is not a simple lack of knowledge but an active aversion to knowledge, the refusal to know, issuing from cowardice, pride, or laziness of mind.
A theory which is not refutable by any conceivable event is non-scientific.
Irrefutability is not a virtue of a theory (as people often think) but a vice.
I may be wrong and you may be right, and by an effort, we may get nearer to the truth
The attempt to make heaven on earth invariably produces hell.
Those who promise us paradise on earth never produced anything but a hell.
We do not choose political freedom because it promises us this or that.
We choose it because it makes possible the only dignified form of human coexistence, the only form in which we can be fully responsible for ourselves. Whether we realize its possibilities depends on all kinds of things — and above all on ourselves.
Evolution is not a fact. Evolution doesn't even qualify as a theory or as a hypothesis. It is a metaphysical research program, and it is not really testable science.
We all remember how many religious wars were fought for a religion of love and gentleness; how many bodies were burned alive with the genuinely kind intention of saving souls from the eternal fire of hell.
Our aim as scientists is objective truth;
more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.
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.
We have the right not to tolerate the intolerant.
We should tolerate even them whenever we can do so without running a great risk; but the risk may become so great that we cannot allow ourselves the luxury.
Optimism is a duty. The future is open. It is not predetermined. No one can predict it, except by chance. We all contribute to determining it by what we do. We are all equally responsible for its success.
We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.
In my view, aiming at simplicity and lucidity is a moral duty of all intellectuals: lack of clarity is a sin, and pretentiousness is a crime.
Bold ideas, unjustified anticipations, and speculative thought, are our only means for interpreting nature: our only organon, our only instrument, for grasping her. And we must hazard them to win our prize. Those among us who are unwilling to expose their ideas to the hazard of refutation do not take part in the scientific game.
no matter how many instances of white swans we may have observed, this does not justify the conclusion that all swans are white.
It is impossible to speak in such a way that you cannot be misunderstood.
The difference between the amoeba and Einstein is that, although both make use of the method of trial and error elimination, the amoeba dislikes erring while Einstein is intrigued by it.
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.
A rationalist is simply someone for whom it is more important to learn than to be proved right; someone who is willing to learn from others - not by simply taking over another's opinions, but by gladly allowing others to criticize his ideas and by gladly criticizing the ideas of others
. . . it seems to me certain that more people are killed out of righteous stupidity than out of wickedness.
Every solution of a problem raises new unsolved problems.
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.
Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now. Our fellow men have a claim to our help; no generation must be sacrificed for the sake of future generations.
There is an almost universal tendency, perhaps an inborn tendency, to suspect the good faith of a man who holds opinions that differ from our own opinions. It obviously endangers the freedom and the objectivity of our discussion if we attack a person instead of attacking an opinion or, more precisely, a theory.
If we wish our civilization to survive we must break with the habit of deference to great men.
It can't happen here is always wrong: a dictatorship can happen anywhere.
Science is perhaps the only human activity in which errors are systematically criticized and, in time, corrected.
We are social creatures to the inmost centre of our being.
The notion that one can begin anything at all from scratch, free from the past, or unindebted to others, could not conceivably be more wrong.
Rationalism is an attitude of readiness to listen to contrary arguments and to learn from experience... of admitting that "I may be wrong and you may be right and, by an effort, we may get nearer the truth."
I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.
It is wrong to ask who will rule. The ability to vote a bad government out of office is enough. That is democracy.
[Great scientists] are men of bold ideas, but highly critical of their own ideas: they try to find whether their ideas are right by trying first to find whether they are not perhaps wrong. They work with bold conjectures and severe attempts at refuting their own conjectures.
We know a great deal, but our ignorance is sobering and boundless.
With each step forward, with each problem which we solve, we not only discover new and unsolved problems, but we also discover that where we believed that we were standing on firm and safe ground, all things are, in truth, insecure and in a state of flux.
Science may be described as the art of systematic over-simplification.
We have become makers of our fate when we have ceased to pose as its prophets.
All life is problem solving
Our knowledge can only be finite, while our ignorance must necessarily be infinite.
We never know what we are talking about.
All we can do is search for the falsity content in our best theory.
It is complete nihilism to propose laying down arms in a world where atom bombs are around. It is very simple: there is no way of achieving peace other than with weapons.
The quest for precision is analogous to the quest for certainty and both - precision and certainty are impossible to attain.