Karl Popper Quotes

What a monument of human smallness is this idea of the philosopher king. What a contrast between it and the simplicity of humaneness of Socrates, who warned the statesmen against the danger of being dazzled by his own power, excellence, and wisdom, and who tried to teach him what matters most — that we are all frail human beings.

It is under the influence of such romantic ideas that individualism is still identified with egoism, as it was by Plato, and altruism with collectivism (i.e. with the substitution of group egoism for the individualist egoism). But this bars the way even to a clear formulation of the main problem, the problem of how to obtain a sane appreciation of one’s own importance in relation to other individuals. Since it is felt, and rightly so, that we have to aim at something beyond our own selves, something to which we can devote ourselves, and for which we may make sacrifices, it is concluded that this must be the collective, with its ‘historical mission’. Thus we are told to make sacrifices, and, at the same time, assured that we shall make an excellent bargain by doing so. We shall make sacrifices, it is said, but we shall thereby obtain honour and fame. We shall become ‘leading actors’, heroes on the Stage of History; for a small risk we shall gain great rewards. This is the dubious morality of a period in which only a tiny minority counted, and in which nobody cared for the common people. It is the morality of those who, being political or intellectual aristocrats, have a chance of getting into the textbooks of history. It cannot possibly be the morality of those who favour justice and equalitarianism; for historical fame cannot be just, and it can be attained only by a very few. The countless number of men who are just as worthy, or worthier, will always be forgotten.

There are all kinds of sources of our knowledge; but none has authority ... The fundamental mistake made by the philosophical theory of the ultimate sources of our knowledge is that it does not distinguish clearly enough between questions of origin and questions of validity.

What we need and what we want is to moralize politics, not to politicize morals.

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. [...] We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.

Never can an authority admit that the intellectually courageous - those who dare to defy his authority - may be the most valuable type.

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.

It has always been asked in the spirit of: ‘What are the best sources of our knowledge – the most reliable ones, those which will not lead us into error, and those to which we can and must turn, in case of doubt, as the last court of appeal?’ I propose to assume, instead, that no such ideal sources exist – no more than ideal rulers – and that all ‘sources’ are liable to lead us into errors at times. And I propose to replace, therefore, the question of the sources of our knowledge by the entirely different question: ‘How can we hope to detect and eliminate error?’ The question of the sources of our knowledge, like so many authoritarian questions, is a genetic one. It asks for the origin of our knowledge, in the belief that knowledge may legitimize itself by its pedigree. The nobility of the racially pure knowledge, the untainted knowledge, the knowledge which derives from the highest authority, if possible from God: these are the (often unconscious) metaphysical ideas behind the question. My modified question, ‘How can we hope to detect error?’ may be said to derive from the view that such pure, untainted and certain sources do not exist, and that questions of origin or of purity should not be confounded with questions of validity, or of truth. …. The proper answer to my question ‘How can we hope to detect and eliminate error?’ is I believe, ‘By criticizing the theories or guesses of others and – if we can train ourselves to do so – by criticizing our own theories or guesses.’ …. So my answer to the questions ‘How do you know? What is the source or the basis of your assertion? What observations have led you to it?’ would be: ‘I do not know: my assertion was merely a guess. Never mind the source, or the sources, from which it may spring – there are many possible sources, and I may not be aware of half of them; and origins or pedigrees have in any case little bearing upon truth. But if you are interested in the problem which I tried to solve by my tentative assertion,

I would rather find a single causal law than be the king of Persia!

For myself, I am interested in science and in philosophy only because I want to learn something about the riddle of the world in which we live, and the riddle of man's knowledge of that world. And I believe that only a revival of interest in these riddles can save the sciences and philosophy from an obscurantist faith in the expert's special skill and in his personal knowledge and authority.

I wish to apologize to the Kantians for mentioning them in the same breath as the Hegelians.

I do not overlook the fact that there are irrationalists who love mankind, and that not all forms of irrationalism engender criminality. But I hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate. (Socrates, I believe, saw something of this when he suggested that mistrust or hatred of argument is related to mistrust or hatred of man).

Our knowledge can only be finite, while our ignorance must necessarily be infinite.

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.

The way of science is paved with discarded theories which were once declared self-evident;