Karl Popper Quotes

Marxism is only an episode — one of the many mistakes we have made in the perennial and dangerous struggle for building a better and freer world.

Those who promise us paradise on earth never produced anything but a hell.

Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship. We should replace it by a more modest and more realistic principle — the principle that the fight against avoidable misery should be a recognized aim of public policy, while the increase of happiness should be left, in the main, to private initiative.

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,

In previous chapters I have mentioned moral positivism (especially that of Hegel), the theory that there is no moral standard but the one which exists; that what is, is reasonable and good; and therefore, that might is right. The practical aspect of this theory is this. A moral criticism of the existing state of affairs is impossible, since this state itself determines the moral standard of things. Now the historicist moral theory we are considering is nothing but another form of moral positivism. For it holds that coming might is right. The future is here substituted for the present — that is all. And the practical aspect of the theory is this. A moral criticism of the coming state of affairs is impossible, since this state determines the moral standard of things. The difference between ‘the present’ and ‘the future’ is here, of course, only a matter of degree. One can say that the future starts to-morrow, or in 500 years, or in 100. In their theoretical structure there is no difference between moral conservatism, moral modernism, and moral futurism. Nor is there much to choose between them in regard to moral sentiments. If the moral futurist criticizes the cowardice of the moral conservative who takes sides with the powers that be, then the moral conservative can return the charge; he can say that the moral futurist is a coward since he takes sides with the powers that will be, with the rulers of to-morrow. I feel sure that, had he considered these implications, Marx would have repudiated historicist moral theory. Numerous remarks and numerous actions prove that it was not a scientific judgement but a moral impulse, the wish to help the oppressed, the wish to free the shamelessly exploited and miserable workers, which led him to socialism. I do not doubt that it is this moral appeal that is the secret of the influence of his teaching. And the force of this appeal was tremendously strengthened by the fact that he did not preach morality in the abstract. He did not

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.

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.

A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.

I hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate.

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;

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

...if God had wanted to put everything into the world from the beginning, He would have created a universe without change, without organisms and evolution, and without man and man's experience of change. But He seems to have thought that a live universe with events unexpected even by Himself would be more interesting than a dead one.

The aim of argument, or of discussion, should not be victory but progress.

For it was my master who taught me not only how very little I knew but also that any wisdom to which I might ever aspire could consist only in realizing more fully the infinity of my ignorance.