Karl Popper Quotes

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.

My argument against a naive form of empiricism was essentially anticipated by Mark Twain. On his first appointment as a reporter, he tells us, the editor of the newspaper instructed him never to report anything unless he could verify it or confirm it by personal knowledge. So he described a social event as follows: 'A woman giving the name of Mrs James Jones, who is reported to be one of the society leaders of the city, is said to have given what purported to be a party yesterday to a number of alleged ladies. The hostess claims to be the wife of a reputed attorney.'

One sees that Mark Twain was quick to realize the silliness of the naive empiricist (verificationist) theory of the sources of our knowledge.

The 'conspiracy theory of society' is a typical result of a secularization of a religious superstition. The belief in the Homeric gods whose conspiracies explain the history of the Trojan War is gone. The gods are abandoned. But their place is filled by powerful men or groups - sinister pressure groups whose wickedness is responsible for all the evils we suffer from - such as the Learned Elders of Zion, or the monopolists, or the capitalists, or the imperialists.

The essential feature of dualist-interactionism is that the mind and brain are independent entities...and that they interact by quantum physics.

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.

Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testabilty: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.

For nothing could be better than living a modest, simple, and free life in an egalitarian society. It took some time before I recognized this as no more than a beautiful dream; that freedom is more important than equality; that the attempt to realize equality endangers freedom; and that, if freedom is lost, there will not even be equality among the unfree.

It has always been asked in the spirit of: ‘What are the best sources of our knowledge – the most reliable ones, those which will not lead us into error, and those to which we can and must turn, in case of doubt, as the last court of appeal?’ I propose to assume, instead, that no such ideal sources exist – no more than ideal rulers – and that all ‘sources’ are liable to lead us into errors at times. And I propose to replace, therefore, the question of the sources of our knowledge by the entirely different question: ‘How can we hope to detect and eliminate error?’ The question of the sources of our knowledge, like so many authoritarian questions, is a genetic one. It asks for the origin of our knowledge, in the belief that knowledge may legitimize itself by its pedigree. The nobility of the racially pure knowledge, the untainted knowledge, the knowledge which derives from the highest authority, if possible from God: these are the (often unconscious) metaphysical ideas behind the question. My modified question, ‘How can we hope to detect error?’ may be said to derive from the view that such pure, untainted and certain sources do not exist, and that questions of origin or of purity should not be confounded with questions of validity, or of truth. …. The proper answer to my question ‘How can we hope to detect and eliminate error?’ is I believe, ‘By criticizing the theories or guesses of others and – if we can train ourselves to do so – by criticizing our own theories or guesses.’ …. So my answer to the questions ‘How do you know? What is the source or the basis of your assertion? What observations have led you to it?’ would be: ‘I do not know: my assertion was merely a guess. Never mind the source, or the sources, from which it may spring – there are many possible sources, and I may not be aware of half of them; and origins or pedigrees have in any case little bearing upon truth. But if you are interested in the problem which I tried to solve by my tentative assertion,

The empirical basis of objective science has thus nothing ‘absolute’ about it.4 Science does not rest upon solid bedrock. The bold structure of its theories rises, as it were, above a swamp. It is like a building erected on piles. The piles are driven down from above into the swamp, but not down to any natural or ‘given’ base; and if we stop driving the piles deeper, it is not because we have reached firm ground. We simply stop when we are satisfied that the piles are firm enough to carry the structure, at least for the time being.

We can all participate in the heritage of man. We all can help to preserve it. And we can all make our own modest contribution to it.
We must not as for more.

Criticism, I said, is an attempt to find the weak spots in a theory, and these, as a rule, can be found only in the more remote logical consequences which can be derived from it. It is here that purely logical reasoning plays an important part in science.

Democracy provides the institutional framework for the reform of political institutions (other than this framework). It makes possible the reform of institutions without using violence, and thereby the use of reason in the designing of new institutions and the adjusting of old ones. It cannot provide reason. The question of the intellectual and moral standard of its citizens is to a large degree a personal problem. (The idea that this problem can be tackled, in turn, by an institutional eugenic and educational control is, I believe, mistaken ; some reasons for my belief will be given below.) It is quite wrong to blame democracy for the political shortcomings of a democratic state. We should rather blame ourselves. In a non-democratic state, the only way to achieve reasonable reforms is by the violent overthrow of the government, and the introduction of a democratic framework. Those who criticize democracy on any ' moral ' grounds fail to distinguish between personal and institutional problems. It rests with us to improve matters. The democratic institutions cannot improve themselves. The problem of improving them is always a problem of persons rather than of institutions.

This is why the conflict between rationalism and irrationalism has become the most important intellectual, and perhaps even moral, issue of our time.

Science is most significant as one of the greatest spiritual adventures that man has yet known.

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