Karl Popper, fully Sir Karl Raimund Popper

Popper, fully Sir Karl Raimund Popper

Austro-British Scientific Philosopher and Professor at the London School of Economics

Author Quotes

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."

The conspiracy theory of society... comes from abandoning god and then asking: "Who is in his place"

The moral decisions of others should be treated with respect, as long as such decisions do not conflict with the principle of tolerance.

There can be no ultimate statements science: there can be no statements in science which can not be tested, and therefore none which cannot in principle be refuted, by falsifying some of the conclusions which can be deduced from them.

We do not know anything - this is the first. Therefore, we should be very modest - this is the second. Not to claim that we do know when we do not - this is the third. That's the kind of attitude I'd like to popularize. There is little hope for success.

With regards to political enemies Plato had a kill-and-banish principle... In interpreting it , modern-day Platonists are clearly disturbed by it, even as they make elaborate attempts to defend Plato.

Reason like science, grows by way of mutual criticism; the only possible way of planning its growth is to develop those institutions that safeguard. the freedom of thought

The defense of democracy must consist in making anti-democratic experiences too costly for those who try them; much more costly than a democratic compromise

The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance ? the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite.

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.

We do not know. We can only guess.

You can choose whatever name you like for the two types of government. I personally call the type of government which can be removed without violence "democracy," and the other, "tyranny."

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 when we cease our attempts to drive our piles into a deeper layer, it is not because we have reached firm ground. We simply stop when we are satisfied that they are firm enough to carry the structure, at least for the time being.

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.

The only way to test a hypothesis is to look for all the information that disagrees with it.

There is no history, only histories.

We hate the very idea that our own ideas may be mistaken, so we cling dogmatically to our conjectures.

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

Science is not a system of certain, or -established, statements; nor is it a system which steadily advances towards a state of finality... And our guesses are guided by the unscientific, the metaphysical (though biologically explicable) faith in laws, in regularities which we can uncover?discover. Like Bacon, we might describe our own contemporary science?'the method of reasoning which men now ordinarily apply to nature'?as consisting of 'anticipations, rash and premature' and as 'prejudices'.

The difficulties connected with my criterion of demarcation (D) are important, but must not be exaggerated. It is vague, since it is a methodological rule, and since the demarcation between science and nonscience is vague. But it is more than sharp enough to make a distinction between many physical theories on the one hand, and metaphysical theories, such as psychoanalysis, or Marxism (in its present form), on the other. This is, of course, one of my main theses; and nobody who has not understood it can be said to have understood my theory.

The paradox of tolerance: 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 against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.?In this formulation, I do not imply, for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check by public opinion, suppression would certainly be most unwise. But we should claim the right to suppress them if necessary even by force; for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols. We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant. We should claim that any movement preaching intolerance places itself outside the law, and we should consider incitement to intolerance and persecution as criminal, in the same way as we should consider incitement to murder, or to kidnapping, or to the revival of the slave trade, as criminal.

There is no pure, disinterested, theory-free observation,

We have become makers of our fate when we have ceased to pose as its prophets.

Science is one of the very few human activities - perhaps the only one - in which errors are systematically criticized and fairly often, in time, corrected. This is why we can say that, in science, we often learn from our mistakes, and why we can speak clearly and sensibly about making progress there.

The early Greek tribal society resembles in many respects that of peoples like the Polynesians, the Maoris for instance. Small bands of warriors, usually living in fortified settlements, ruled by tribal chiefs or kings, or by aristocratic families, were waging war against one another on sea as well as on land.

Author Picture
First Name
Last Name
Popper, fully Sir Karl Raimund Popper
Birth Date
Death Date

Austro-British Scientific Philosopher and Professor at the London School of Economics