Karl Popper Quotes

The true Enlightenment thinker, the true rationalist, never wants to talk anyone into anything. No, he does not even want to convince; all the time he is aware that he may be wrong. Above all, he values the intellectual independence of others too highly to want to convince them in important matters. He would much rather invite contradiction, preferably in the form of rational and disciplined criticism. He seeks not to convince but to arouse — to challenge others to form free opinions.

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 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.

The difference between Plato’s theory on the one hand, and that of the Old Oligarch and the Thirty on the other, is due to the influence of the Great Generation. Individualism, equalitarianism, faith in reason and love of freedom were new, powerful, and, from the point of view of the enemies of the open society, dangerous sentiments that had to be fought. Plato had himself felt their influence, and, within himself, he had fought them. His answer to the Great Generation was a truly great effort. It was an effort to close the door which had been opened, and to arrest society by casting upon it the spell of an alluring philosophy, unequalled in depth and richness. In the political field he added but little to the old oligarchic programme against which Pericles had once argued64. But he discovered, perhaps unconsciously, the great secret of the revolt against freedom, formulated in our own day by Pareto65; ‘To take advantage of sentiments, not wasting one’s energies in futile efforts to destroy them.’ Instead of showing his hostility to reason, he charmed all intellectuals with his brilliance, flattering and thrilling them by his demand that the learned should rule. Although arguing against justice he convinced all righteous men that he was its advocate. Not even to himself did he fully admit that he was combating the freedom of thought for which Socrates had died; and by making Socrates his champion he persuaded all others that he was fighting for it. Plato thus became, unconsciously, the pioneer of the many propagandists who, often in good faith, developed the technique of appealing to moral, humanitarian sentiments, for anti-humanitarian, immoral purposes. And he achieved the somewhat surprising effect of convincing even great humanitarians of the immorality and selfishness of their creed66. I do not doubt that he succeeded in persuading himself. He transfigured his hatred of individual initiative, and his wish to arrest all change, into a love of justice and tempera

Is it within the power of any social science to make sweeping historical prophecies? Can we expect to get more than the irresponsible reply of the soothsayer if we ask a man what the future has in store for mankind?

An argument which appeals to the fact that we possess knowledge or that we can learn from experience, and which concludes from this fact that knowledge or learning from experience must be possible, and further, that every theory which entails the impossibility of knowledge, or of learning from experience, must be false, may be
called a ‘transcendental argument’.

The question of the acceptance of theories should, I propose, be demoted to the status of a minor problem. For science may be regarded as a growing system of problems, rather than as a system of beliefs. And for a system of problems, the tentative acceptance of a theory or a conjecture means hardly more than that it is considered worthy of further criticism.

A theory that explains everything, explains nothing.

When we enter a new situation in life and are confronted by a new person, we bring with us the prejudices of the past and our previous experiences of people. These prejudices we project upon the new person. Indeed, getting to know a person is largely a matter of withdrawing projections; of dispelling the smoke screen of what we imagine he is like and replacing it with the reality of what he is actually like.

The deepest, the only theme of human history, compared to which all others are of subordinate importance, is the conflict of skepticism with faith.

To be ignorant of the past is to remain a child.

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.

Why do I think that we, the intellectuals, are able to help? Simply because we, the intellectuals, have done the most terrible harm for thousands of years. Mass murder in the name of an idea, a doctrine, a theory, a religion — that is all our doing, our invention: the invention of the intellectuals. If only we would stop setting man against man — often with the best intentions — much would be gained. Nobody can say that it is impossible for us to stop doing this.

There are uncertain truths — even true statements that we may take to be false — but there are no uncertain certainties. Since we can never know anything for sure, it is simply not worth searching for certainty; but it is well worth searching for truth; and we do this chiefly by searching for mistakes, so that we have to correct them.

All things living are in search of a better world.

'[S]cientific knowledge' always remained sheer guesswork... controlled by criticism and experiment. ...[T]his assumption is sufficient for solving the problem of induction—called by Kant 'the problem of Hume'— without sacrificing empiricism...[i.e.,] without adopting a principle of induction and ascribing to it a priori validity. For guesses are not 'induced from observations' (although they may ...be suggested ...by observations). This ... allows us to accept ...(...without Russell's limits of empiricism) Hume's logical criticism of induction and to give up ...an inductive logic, for certainty, and even for probability, while continuing ...scientific search for truth.