Karl Popper, fully Sir Karl Raimund Popper

Popper, fully Sir Karl Raimund Popper

Austro-British Scientific Philosopher and Professor at the London School of Economics

Author Quotes

No number of sightings of white swans can prove the theory that all swans are white. The sighting of just one black one may disprove it.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research program.

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.

It is not possible to write clearly enough to avoid being misrepresented by people who are sufficiently determined to do so.

No particular theory may ever be regarded as absolutely certain.... No scientific theory is sacrosanct.

I have insisted that we must be tolerant. But I also believe that this tolerance has its limits. We must not trust those anti-humanitarian religions which not only preach destruction but act accordingly. For if we tolerate them, then we become ourselves responsible for their deeds.

If our civilization is to survive, we must break with the habit of deference to great men. Great men may make great mistakes; ...some of the greatest leaders of the past supported the perennial attack on freedom and reason.

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 righteous stupidity will be the more fruitful the more the partner's backgrounds differ.

No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.

I have learned more from Hayek than from any other living thinker, except perhaps Alfred Tarski - but not even excepting Russell.

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.

It is our duty to help those who need help; but it cannot be our duty to make others happy, since this does not depend on us, and since it would only too often mean intruding on the privacy of those towards whom we have such amiable intentions.

'Normal' science, in Kuhn's sense, exists. It is the activity of the non-revolutionary, or more precisely, the not-too-critical professional: of the science student who accepts the ruling dogma of the day... in my view the 'normal' scientist, as Kuhn describes him, is a person one ought to be sorry for... He has been taught in a dogmatic spirit: he is a victim of indoctrination... I can only say that I see a very great danger in it and in the possibility of its becoming normal... a danger to science and, indeed, to our civilization. And this shows why I regard Kuhn's emphasis on the existence of this kind of science as so important.

I have spoken to Einstein and he admitted to me that his theory was in fact no different from the one of Parmenides.

If we wish our civilization to survive we must break with the habit of deference to great men.

It is part of my thesis that all our knowledge grows only through the correcting of our mistakes.

Not only do I hate violence, but I firmly believe that the fight against it is not hopeless. I realize that the task is difficult. I realize that, only too often in the course of history, it has happened that what appeared at first to be a great success in the fight against violence was followed by a defeat. I do not overlook the fact that the new age of violence which was opened by the two World wars is by no means at an end. 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 hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate.

If you can't say it simply and clearly, keep quiet, and keep working on it till you can.

It is the rule which says that the other rules of scientific procedure must be designed in such a way that they do not protect any statement in science against falsification.

Now this principle of induction cannot be a purely logical truth like a tautology or an analytic statement. Indeed, if there were such a thing as a purely logical principle of induction, there would be no problem of induction; for in this case, all inductive inferences would have to be regarded as purely logical or tautological transformations, just like inferences in inductive logic. Thus the principle of induction must be a synthetic statement; that is, a statement whose negation is not self-contradictory but logically possible. So the question arises why such a principle should be accepted at all, and how we can justify its acceptance on rational grounds.

I may be wrong and you may be right, and by an effort, we may get nearer to the truth.

If you know that things are bound to happen whatever you do, then you may feel free to give up the fight against them.

It is wrong and dangerous to extol freedom by telling people that they will certainly be all right once they are free... The most we can say of democracy or freedom is that they give our personal abilities a little more influence on our well-being.

Optimism is a duty. The future is open. It is not predetermined. No one can predict it, except by chance. We all contribute to determining it by what we do. We are all equally responsible for its success.

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Popper, fully Sir Karl Raimund Popper
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Austro-British Scientific Philosopher and Professor at the London School of Economics