Karl Popper Quotes

The doctrine that there is as much science in a subject as... mathematics in it, or as much... measurement or 'precision' in it, rests upon... misunderstanding.

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

Philosophy is a necessary activity because we, all of us, take a great number of things for granted, and many of these assumptions are of a philosophical character; we act on them in private life, in politics, in our work, and in every other sphere of our lives — but while some of these assumptions are no doubt true, it is likely, that more are false and some are harmful. So the critical examination of our presuppositions — which is a philosophical activity — is morally as well as intellectually important.

Aestheticism and radicalism must lead us to jettison reason, and to replace it by a desperate hope for political miracles. This irrational attitude which springs from intoxication with dreams of a beautiful world is what I call Romanticism. It may seek its heavenly city in the past or in the future; it may preach ‘back to nature’ or ‘forward to a world of love and beauty’; but its appeal is always to our emotions rather than to reason. Even with the best intentions of making heaven on earth it only succeeds in making it a hell – that hell which man alone prepares for his fellow-men.

Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.

It is interesting that for Plato, and for most Platonists, an altruistic individualism cannot exist. According to Plato, the only alternative to collectivism is egoism; he simply identifies all altruism with collectivism, and all individualism with egoism. This is not a matter of terminology, of mere words, for instead of four possibilities, Plato recognized only two. This has created considerable confusion in speculation on ehtical matters, even down to our own day.

Plato’s identification of individualism with egoism furnishes him with a powerful weapon for his defence of collectivism as well as for his attack upon individualism. In defending collectivism, he can appeal to our humanitarian feeling of unselfishness; in his attack, he can brand all individualists as selfish, as incapable of devotion to anything but themselves. This attack, although aimed by Plato against individualism in our sense, i.e. against the rights of human individuals, reaches of course only a very different target, egoism. But this difference is constantly ignored by Plato and by most Platonists...

Individualism was part of the old intuitive idea of justice. That justice is not, as Plato would have it, the health and harmony of the state, but rather a certain way of treating individuals, is emphasized by Aristotle, when he says, ‘justice is something that pertains to persons.

In brief, it is my thesis that human misery is the most urgent problem of a rational public policy and that happiness is not such a problem.

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.

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.

What we should do, I suggest, is to give up the idea of ultimate sources of knowledge, and admit that all knowledge is human; that it is mixed with our errors, our prejudices, our dreams, and our hopes; that all we can do is to grope for truth even though it be beyond our reach. We may admit that our groping is often inspired, but we must be on our guard against the belief, however deeply felt, that our inspiration carries any authority, divine or otherwise. If we thus admit that there is no authority beyond the reach of criticism to be found within the whole province of our knowledge, however far it may have penetrated into the unknown, then we can retain, without danger, the idea that truth is beyond human authority. And we must retain it. For without this idea there can be no objective standards of inquiry; no criticism of our conjectures; no groping for the unknown; no quest for knowledge.

Instead of the greatest happiness for the greatest number, one should demand, more modestly, the least amount of avoidable suffering for all; and further, that unavoidable suffering — such as hunger in times of an unavoidable shortage of food — should be distributed as equally as possible.

Historically, all ethics undoubtedly begin with religion; but I do not now deal with historical questions. I do not ask who was the first lawgiver. I only maintain that it is we, and we alone, who are responsible for adopting or rejecting some suggested moral laws; it is we who must distinguish between the true prophets and the false prophets. All kinds of norms have been claimed to be God-given. If you accept 'Christian' ethics of equality and toleration and freedom of conscience only because of its claim to rest upon divine authority, then you build on a weak basis; for it has been only too often claimed that inequality is willed by God, and that we must not be tolerant with unbelievers. If, however, you accept the Christian ethics not because you are commanded to do so but because of your conviction that it is the right decision to take, then it is you who have decided.

Science is not a system of certain, or well established, statements; nor is it a statement which steadily advances towards state of finality. Our science is not knowledge (epistēmē): it can newer claim to have attained truth, or even substitute for it, such as probability. . . . We do not know; we can only guess.

I see now more clearly than ever before that even our greatest troubles spring from something that is as admirable and sound as it is dangerous — from our impatience to better the lot of our fellows. For these troubles are the by-products of what is perhaps the greatest of all moral and spiritual revolutions of history, a movement which began three centuries ago. It is the longing of uncounted unknown men to free themselves and their minds from the tutelage of authority and prejudice. It is their attempt to build up an open society which rejects the absolute authority to preserve, to develop, and to establish traditions, old or new, that measure up to their standards of freedom, of humaneness, and of rational criticism. It is their unwillingness to sit back and leave the entire responsibility for ruling the world to human or superhuman authority,and their readiness to share the burden of responsibility for avoidable suffering, and to work for its avoidance. This revolution has created powers of appalling destructiveness; but they may yet be conquered.

Despite my admiration for scientific knowledge, I am not an adherent of scientism. For scientism dogmatically asserts the authority of scientific knowledge; whereas I do not believe in any authority and have always resisted dogmatism; and I continue to resist it, especially in science. I am opposed to the thesis that the scientist must believe in his theory. As far as I am concerned “I do not believe in belief,” as E. M. Forster says; and I especially do not believe in belief in science. I believe at most that belief has a place in ethics, and even here only in a few instances. I believe, for example, that objective truth is a value — that is, an ethical value, perhaps the greatest value there is — and that cruelty is the greatest evil.