Karl R. Popper

While differing widely in the various little bits we know, in our infinite ignorance we are all equal.

Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.

The difficulties connected with my criterion of demarcation (D) are important, but must not be exaggerated. It is vague, since it is a methodological rule, and since the demarcation between science and nonscience is vague. But it is more than sharp enough to make a distinction between many physical theories on the one hand, and metaphysical theories, such as psychoanalysis, or Marxism (in its present form), on the other. This is, of course, one of my main theses; and nobody who has not understood it can be said to have understood my theory.The situation with Marxism is, incidentally, very different from that with psychoanalysis. Marxism was once a scientific theory: it predicted that capitalism would lead to increasing misery and, through a more or less mild revolution, to socialism; it predicted that this would happen first in the technically highest developed countries; and it predicted that the technical evolution of the 'means of production' would lead to social, political, and ideological developments, rather than the other way round.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.Thus one might say that Marxism was once a science, but one which was refuted by some of the facts which happened to clash with its predictions (I have here mentioned just a few of these facts).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__s a metaphysical dream, if you like, married to a cruel reality.Psychoanalysis is a very different case. It is an interesting psychological metaphysics (and no doubt there is some truth in it, as there is so often in metaphysical ideas), but it never was a science. There may be lots of people who are Freudian or Adlerian cases: Freud himself was clearly a Freudian case, and Adler an Adlerian case. But what prevents their theories from being scientific in the sense here described is, very simply, that they do not exclude any physically possible human behaviour. Whatever anybody may do is, in principle, explicable in Freudian or Adlerian terms. (Adler's break with Freud was more Adlerian than Freudian, but Freud never looked on it as a refutation of his theory.)The point is very clear. Neither Freud nor Adler excludes any particular person's acting in any particular way, whatever the outward circumstances. Whether a man sacrificed his life to rescue a drowning, child (a case of sublimation) or whether he murdered the child by drowning him (a case of repression) could not possibly be predicted or excluded by Freud's theory; the theory was compatible with everything that could happen__ven without any special immunization treatment.Thus while Marxism became non-scientific by its adoption of an immunizing strategy, psychoanalysis was immune to start with, and remained so. In contrast, most physical theories are pretty free of immunizing tactics and highly falsifiable to start with. As a rule, they exclude an infinity of conceivable possibilities.

Denying realism amounts to megalomania.

It is often asserted that, in view of the situation in quantum theory, object and subject can no longer be sharply separated. 1 To use Heitler__ words, the __eparation of the world into an __bjective outside reality_, and __s_, the self-conscious onlookers, can no longer be maintained. Object and subject become inseparable from each other_. 2 This, according to Bohr, is due to __he impossibility of any sharp separation between the behaviour of atomic objects and the interaction with the measuring instruments which serve to define the conditions under which the phenomena appear_. 3 Heitler elaborates the point in some detail. __ne may ask_, he writes, __f it is sufficient to carry out a measurement by a self-registering apparatus or whether the presence of an observer is required._ And he arrives at the conclusion that the self-registering apparatus is insufficient, and that __he observer appears, as a necessary part of the whole structure, and in his full capacity as a conscious being_.

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 __ack to nature_ or __orward 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.

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

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

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.

I remained a socialist for several years, even after my rejection of Marxism; and if there could be such a thing as socialism combined with individual liberty, I would be a socialist still. 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 is complete nihilism to propose laying down arms in a world where atom bombs are around. It is very simple: there is no way of achieving peace other than with weapons.

We all have an unscientific weakness for being always in the right, and this weakness seems to be particularly common among professional and amateur politicians. But the only way to apply something like scientific method in politics is to proceed on the assumption that there can be no political move which has no drawbacks, no undesirable consequences. To look out for these mistakes, to find them, to bring them into the open, to analyse them, and to learn from them, this is what a scientific politician as well as a political scientist must do. Scientific method in politics means that the great art of convincing ourselves that we have not made any mistakes, of ignoring them, of hiding them, and of blaming others from them, is replaced by the greater art of accepting the responsibility for them, of trying to learn from them, and of applying this knowledge so that we may avoid them in future.

The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know; our knowledge of our ignorance. For this indeed, is the main source of our ignorance - the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite.

Science may be described as the art of systematic oversimplification.

No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it

We are social creatures to the inmost centre of our being. The notion that one can begin anything at all from scratch, free from the past, or unindebted to others, could not conceivably be more wrong.

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.

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.