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

A rationalist, as I use the word, is a man who attempts to reach decisions by argument and perhaps, in certain cases, by compromise, rather than by violence. He is a man who would rather be unsuccessful in convincing another man by argument than successful in crushing him by force, by intimidation and threats, or even by persuasive propaganda.

But I shall certainly admit a system as empirical or scientific only if it is capable of being tested by experience. These considerations suggest that not the verifiability but the falsifiability of a system is to be taken as a criterion of demarcation. In other words: I shall not require of a scientific system that it shall be capable of being singled out, once and for all, in a positive sense; but I shall require that its logical form shall be such that it can be singled out, by means of empirical tests, in a negative sense: it must be possible for an empirical scientific system to be refuted by experience. (1959)

Great men may make great mistakes.

A system is empirical or scientific only if it is capable of being tested by experience. These considerations suggest that not the verifiability but the falsifiability of a system is to be taken as a criterion of demarcation... It must be possible for an empirical or scientific system to be refuted by experience.

But it is certainly not possible to insist on one hand that the formalism is complete and to insist on the other hand that its application to 'the actual' actually demands a step which cannot be derived from it.

Historically speaking all - or very nearly all - scientific theories originate from myths.

A system such as classical mechanics may be ?scientific? to any degree you like; but those who uphold it dogmatically ? believing, perhaps, that it is their business to defend such a successful system against criticism as long as it is not conclusively disproved ? are adopting the very reverse of that critical attitude which in my view is the proper one for the scientist.

But some of these theories are so bold that they can clash with reality: they are the testable theories of science. And when they clash, then we know that there is a reality; something that can inform us that our ideas are mistaken.

History has no meaning.

A theory is just a mathematical model to describe the observations.

But the (so-called) socialist revolution came first in one of the technically backward countries. And instead of the means of production producing a new ideology, it was Lenin's and Stalin's ideology that Russia must push forward with its industrialization ('Socialism is dictatorship of the proletariat plus electrification') which promoted the new development of the means of production.

However, Marxism is no longer a science; for it broke the methodological rule that we must accept falsification, and it immunized itself against the most blatant refutations of its predictions. Ever since then, it can be described only as nonscience?as a metaphysical dream, if you like, married to a cruel reality.

A theory that explains everything, explains nothing.

Contrary to the outstanding work of art, outstanding theory is susceptible to improvements.

I am opposed to looking upon logic as a kind of game... One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.

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

Darwinism is not a testable scientific theory, but a metaphysical research program. And yet, the theory is invaluable. I do not see how, without it, our knowledge could have grown as it has done since Darwin.

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, and he has a devilish influence on Germany. ? One has to read Heidegger in the original to see what a swindler he was.

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.

Definitions.... are never really needed, and rarely of any use.

I do not believe that human lives may be made the means for satisfying an artist's desire for self-expression. We must demand, rather, that every man should be given, if he wishes, the right to model his life himself, as far as this does not interfere too much with others. Much as I may sympathize with the aesthetic impulse, I suggest that the artist might seek expression in another material. Politics, I demand, must uphold equalitarian and individualistic principles; dreams of beauty have to submit to the necessity of helping men in distress, and men who suffer injustice; and to the necessity of constructing institutions to serve such purposes.

All we can do is search for the falsity content in our best theory.

Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now. Our fellow men have a claim to our help; no generation must be sacrificed for the sake of future generations, for the sake of an ideal of happiness that may never be realized.

I do not overlook the fact that there are irrationalists who love mankind, and that not all forms of irrationalism engender criminality. But I hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate. (Socrates, I believe, saw something of this when he suggested that mistrust or hatred of argument is related to mistrust or hatred of man).

Almost everyone... seems to be quite sure that the differences between the methodologies of history and of the natural sciences are vast. For, we are assured, it is well known that in the natural sciences we start from observation and proceed by induction to theory. And is it not obvious that in history we proceed very differently? Yes, I agree that we proceed very differently. But we do so in the natural sciences as well. In both we start from myths?from traditional prejudices, beset with error?and from these we proceed by criticism: by the critical elimination of errors. In both the role of evidence is, in the main, to correct our mistakes, our prejudices, our tentative theories?that is, to play a part in the critical discussion, in the elimination of error. By correcting our mistakes, we raise new problems. And in order to solve these problems, we invent conjectures, that is, tentative theories, which we submit to critical discussion, directed towards the elimination of error.

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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