Karl Popper Quotes (1902-1994)

“We should realize that from the moral point of view suffering and happiness must not be treated as symmetrical; that is to say, the promotion of happiness is in any case much less urgent than the rendering of help to those who suffer, and the attempt to prevent suffering.”

“We must plan for freedom, and not only for security, if for no other reason than only freedom can make security more secure.”

“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.”

“If your civilization is to survive, we must break with the habit of deference to great men. Great men make mistakes.”

“The theory of natural selection may be so formulated that it is far from tautological. In this case it is not only testable, but it turns out to be not strictly universally true.”

“We should realize that from the moral point of view suffering and happiness must not be treated as symmetrical; that is to say, the promotion of happiness is in any case much less urgent than the rendering of help to those who suffer, and the attempt to prevent suffering.”

“It is often asserted that discussion is only possible between people who have a common language and accept common basic assumptions. I think that this is a mistake. All that is needed is a readiness to learn from one's partner in the discussion, which includes a genuine wish to understand what he intends to say. If this readiness is there, the discussion will be the more fruitful the more the partner's backgrounds differ.”

“We must plan for freedom, and not only for security, if for no other reason than only freedom can make security more secure.”

“No matter how many instances of white swans we may have observed, this does not justify the conclusion that all swans are white.”

“I think that I have learned more from you than from any other living thinker, except perhaps Alfred Tarski … but not even excepting Russell.”

“Socrates had refused to compromise his personal integrity. Plato, with all his uncompromising canvas-cleaning, was led along a path on which he compromised his integrity with every step he took. He was forced to combat free thought and the pursuit of truth. He was led to defend lying, political miracles, tabooistic superstition, the suppression of truth, and ultimately, brutal violence. …The lesson which we thus should learn from Plato is the exact opposite of what he tries to teach us. It is a lesson which must not be forgotten. Excellent as Plato's sociological diagnosis was, his own development proves that the therapy he recommended is worse than the evil he tried to combat.”

“I think that I have learned more from you than from any other living thinker, except perhaps Alfred Tarski... but not even excepting Russell.”

“It was, for all I know, the first deductive theory of the world, the first deductive cosmology: One further step led to theoretical physics, and to the atomic theory.”

“[Bohr was] a marvelous physicist, one of the greatest of all time, but he was a miserable philosopher, and one couldn't talk to him. He was talking all the time, allowing practically only one or two words to you and then at once cutting in.”

“I appeal to the philosophers of all countries to unite and never again mention Heidegger or talk to another philosopher who defends Heidegger. This man was a devil. I mean, he behaved like a devil to his beloved teacher [i.e., Husserl ], and he has a devilish influence on Germany. … One has to read Heidegger in the original to see what a swindler he was.”

“Individualism, united with altruism, has become the basis of our western civilization. It is the central doctrine of Christianity ('love your neighbor,' say the Scriptures, not 'love your tribe'); and it is the core of all ethical doctrines which have grown from our civilization and stimulated it. It is also, for instance, Kant's central practical doctrine ("always recognize that human individuals are ends, and do not use them as mere means to your end.")”

“The Marxist theory of history, in spite of the serious efforts of some of its founders and followers, ultimately adopted this soothsaying practice [of evading testability]. In some of its earlier formulations (for example in Marx's analysis of the character of the 'coming social revolution') their predictions were testable, and in fact falsified. Yet instead of accepting the refutations the followers of Marx re-interpreted both the theory and the evidence in order to make them agree. In this way they rescued the theory from refutation; but they did so at the price of adopting a device which made it irrefutable. They thus gave a 'conventionalist twist' to the theory; and by this stratagem they destroyed its much advertised claim to scientific status.”

“Put in a nut-shell, my thesis amounts to this. The repeated attempts made by Rudolf Carnap to show that the demarcation between science and metaphysics coincides with that between sense and nonsense have failed. The reason is that the positivistic concept of 'meaning' or 'sense' (or of verifiability, or of inductive confirmability, etc.) is inappropriate for achieving this demarcation — simply because metaphysics need not be meaningless even though it is not science. In all its variations demarcation by meaninglessness has tended to be at the same time too narrow and too wide: as against all intentions and all claims, it has tended to exclude scientific theories as meaningless, while failing to exclude even that part of metaphysics which is known as 'rational theology'.”

“Nazism and Fascism are thoroughly beaten, but I must admit that their defeat does not mean that barbarism and brutality have been defeated. On the contrary, it is no use closing our eyes to the fact that these hateful ideas achieved something like a victory in defeat. I have to admit that Hitler succeeded in degrading the moral standards of our Western world, and that in the world of today there is more violence and brutal force than would have been tolerated even in the decade after the first World war. And we must face the possibility that our civilization may ultimately be destroyed by those new weapons which Hitlerism wished upon us, perhaps even within the first decade after the second World war; for no doubt the spirit of Hitlerism won its greatest victory over us when, after its defeat, we used the weapons which the threat of Nazism had induced us to develop.”

“I tried to persuade him to give up his determinism, which amounted to the view that the world was a four-dimensional Parmenidean block universe in which change was a human illusion, or very nearly so. (He agreed that this had been his view, and while discussing it I called him "Parmenides".) I argued that if men, or other organisms, could experience change and genuine succession in time, then this was real. It could not be explained away by a theory of the successive rising into our consciousness of time slices which in some sense coexist; for this kind of "rising into consciousness" would have precisely the same character as that succession of changes which the theory tries to explain away. ... I tried to present to Einstein-Parmenides as strongly as I could my conviction that a clear stand must be made against any idealistic view of time. And I also tried to show that, though the idealistic view was compatible with both determinism and indeterminism, a clear stand should be made in favor of an "open" universe — one in which the future was in no sense contained in the past or the present, even though they do impose severe restrictions on it. I argued that we should not be swayed by our theories to give up realism (for which the strongest arguments were based on common sense), though I think that he was ready to admit, as I was, that we might be forced one day to give it up if very powerful arguments (of Gödel's type, say) were to be brought against it. I therefore argued that with regard to time, and also to indeterminism (that is, the incompleteness of physics), the situation was precisely similar to the situation with regard to realism. Appealing to his own way of expressing things in theological terms, I said: 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.”

“I referred above to the Popperian school as a school, and yet it was not until I came to Sydney from London that I fully realised the extent to which I had been in a school. I found, to my surprise, that there were philosophers influenced by Wittgenstein or Quine or Marx who thought that Popper was quite wrong on many issues, and some who even thought that his views were positively dangerous. I think I have learnt much from that experience. One of the things that I have learnt is that on a number of major issues Popper is indeed wrong, as is argued in the latter portions of this book. However, this does not alter the fact that the Popperian approach is infinitely better than the approach adopted in most philosophy departments that I have encountered.”

“The first article republished in Studies in Philosophy, Politics and Economics, "Degrees of Explanation," originally published in 1955, was largely consistent with Popper's methodology. Hayek embraced Popper's "hypothetico-deductive" approach to science: "The conception of science as a hypothetico-deductive system has been expounded by Karl Popper in a manner which brings out clearly some very important points." Here, as elsewhere in his work, Hayek distinguished between the facts of the natural and social sciences primarily on the basis of their complexity.”

“I learned from Popper what for me is the essence of scientific investigation—how to be speculative and imaginative in the creation of hypotheses, and then to challenge them with the utmost rigor, both by utilizing all existing knowledge and by mounting the most searching experimental attacks. In fact, I learned from him even to rejoice in the refutation of a cherished hypothesis, because that, too, is a scientific achievement and because much has been learned by the refutation.”

“[T]he paradox lurking at the heart of Karl Popper's career... Everyone says this opponent of dogmatism is almost pathologically dogmatic. ...Popper scoffs at scientists’ hope that they can achieve a final theory of nature. "...I think we have gone very far, but we are much further away." He... returns with his book Conjectures and Refutations... [and] reads his own words with reverence: "In our infinite ignorance we are all equal." ...Can a skeptic avoid self-contradiction... the Popper paradox? And if he doesn’t, if he preaches but fails to practice intellectual doubt and humility, does that negate his work? Not at all. Such paradoxes corroborate the skeptic’s point... the quest for truth is endless, twisty and riddled with pitfalls, into which even sharp-eyed seekers tumble. In our infinite ignorance we are all equal.”

“The leading critic of the positivists in their heyday was of course Popper. There has been a tendency for philosophers of science to regard Popper as something of an embarrassment. However, naturalistic philosophers should take it as an interesting fact about science that Popper has long been the favourite philosopher of science among scientists; and it would be condescending to attribute this entirely to the fact that Popper's philosophy is relatively non-complex, self-contained, and flattering to scientists.”

“Socrates (and so Plato) makes it quite clear that the rule of wisdom is tyrannical, and that it cannot tolerate words or deeds, laws or traditional institutions, and certainly political theories that impinge upon its rule. In this sense, modern enemies of Plato's political thought, of whom the most prominent in our time is no doubt Karl Popper, are correct in their objections, although they are ingenuous or let us say insufficiently rigorous in their consideration of the political consequences of theoretical truth. In Popper's case, this is probably due to his conviction that we can establish the falsehood of a proposition but not its truth. This conviction may well be more compatible with democracy in the modern sense of the term than the conviction that genuine philosophers know the truth. The argument of the Republic on the other hand is that, if we did know the truth, we would be led to support a city very much like the one constructed in the Republic under the leadership of Socrates.”

“I do have a great respect for Popper. I mean, I think... he's nearer to... I mean, Popper's ambition, in relation to science, at least, was to discriminate between, sort of, science and what he called pseudo-science.”

“Popper believed that any idea of Utopia is necessarily closed owing to the fact that it chokes its own refutations. The simple notion of a good society that cannot be left open for falsification is totalitarian. I learned from Popper, in addition to the difference between an open and a closed society, that between an open and a closed mind.”

“I read Karl Popper's The Open Society and its Enemies. Popper, whose analysis in many ways complemented that of Hayek, approached Marxism from the point of view of the philosopher of the natural sciences. This meant that he was ideally equipped to expose the fraudulent claim of Marxists to have discovered immutable laws of history, social development or "progress" – laws which were comparable to the laws of natural science. It was not just that the "inevitable" course of events which Marx had prophesied had not occurred and showed no signs of occurring. Marx and Marxists had not even understood the scientific method, let alone practised it in their analysis. Unlike the Marxists – whether historians, economists or social scientists – who tried to "prove" their theories by accumulating more and more facts to sustain them, "the method of science is rather to look out for facts which may refute the theory... and the fact that all tests of the theory are attempted falsifications of predictions derived with its help furnishes the clue to scientific method". The political consequences of this basic error – perhaps more properly described as basic fraud – were summed up by Popper in the dedication of his later book The Poverty of Historicism: "In memory of the countless men, women and children of all creeds or nations or races who fell victims to the fascist and communist belief in Inexorable Laws of Historical Destiny."”

“I got to know Bertrand Russell in the last years of his life. I knew Karl Popper quite well, and they were a whole class above me in intelligence. It wasn’t that I was jealous, it was that I was trying to grapple with these problems with inadequate weaponry… Popper had this originality, Russell had it, and Einstein had it in spades.”