Karl R. Popper Quotes

All life is problem solving

I hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate.

Conjecture or hypothesis must come before observation or perception: we have inborn expectations; we have latent inborn knowledge, in the form of latent expectations, to be activated by a stimuli to which we react as a rule while engaged in active exploration. All learning is a modification (it may be a refutation)of some prior knowledge and thus, in the last analysis, of some inborn knowledge.

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.

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.

The reality of time and change seemed to me the crux of realism.

The future depends on ourselves, and we do not depend on any historical necessity.

Moreover, if we could show, on general logical grounds, that the scientific quest is likely to succeed, one could not understand why anything like success has been so rare in the long history of human endeavours to know more about our world.

What we need and what we want is to moralize politics, not to politicize morals.

I wish to make it clear that 'history' in the sense in which most people speak of it simply does not exist; and this is at least one reason why I say that it has no meaning.

I have in lectures often described this interesting situation by saying: we never know what we are talking about. For when we propose a theory, or try to understand a theory, we also propose, or try to understand, its logical implications; that is, all those statements which follow from it. But this, as we have just seen, is a hopeless task : there is an infinity of unforeseeable nontrivial statements belonging to the informative content of any theory, and an exactly corresponding infinity of statements belonging to its logical content. We can therefore never know or understand all the implications of any theory, or its full significance
Chapter 7

Relativism is one of the many crimes committed by intellectuals. It is a betrayal of reason and of humanity.

From this point of view the question of the scientific status of Darwinian theory - in the widest sense, the theory of trial and error-elimination - becomes an interesting one. I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme - a possible framework for testable scientific theories.

Never let yourself be goaded into taking seriously problems about words and their meanings. What must be taken seriously are questions of fact, and assertions about facts: theories and hypotheses; the problems they solve; and the problems they raise.

Theology, I still think, is due to lack of faith.

Denying realism amounts to megalomania.

The Vienna Circle was empiricist and phenomenalist, Popper was a critical rationalist.

I suggest that the emergence of descriptive language is at the root of the human power of imagination, of human inventiveness, and therefore the emergence of world 3.

I was shocked to have to admit to myself that not only had I accepted a complex theory somewhat uncritically, but that I had also actually noticed quite a bit of what was wrong, in the theory as well as in the practice of communism. But I had repressed this -partly out of loyalty to my friends, partly out of loyalty to "the cause", and partly because there is a mechanism of getting oneself more and more deeply involved: once one has sacrificed one's intellectual conscience over a minor point one doesn't wish to give in too easily; one wishes to justify the self-sacrifice by convincing oneself of the fundamental goodness of the cause, which is seen to outweigh any little moral or intellectual compromise that maybe required. With every such moral or intellectual sacrifice one gets more deeply involved. One becomes ready to back one's moral or intellectual investments in the cause with further investments. It's like being eager to throw good money after bad.

I don't think highly of the theoretical or explanatory power of of the theory of evolution. But I think that an evolutionary approach to biological problems is inescapable, and also that in so desperate a problem situation we must clutch gratefully even at a straw. So, I propose, to start, that we regard the human mind quite naively as if it were a highly developed bodily organ, and that we ask ourselves, as we might with respect to a sense organ, what it contributes to the household of the organism.

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.

I conjecture that the origin of life and the origin of problems coincide.