I am a rationalist. ...I mean ...[I] wish... to understand the world, and to learn by arguing with others. (...I do not say a rationalist holds the m… - Karl Popper

The idea of self-emancipation through knowledge, which was the basic idea of the Enlightenment, is in itself a powerful enemy of fanaticism; for it makes us try hard to detach ourselves or even to dissociate ourselves from our own ideas (in order to look at them critically) instead of identifying ourselves with them. And the recognition of the sometimes overwhelming historical power of ideas should teach us how important it is to free ourselves from the overpowering influence of false or wrong ideas. In the interests of the quest for truth and of our liberation from errors we have to train ourselves to view our own favourite ideas just as critically as those we oppose.

[Ik wil] nogmaals herhalen dat ik wel de aanleiding voor de verwarring was, maar nooit een bijdrage aan de verwarring heb geleverd.

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 — as a metaphysical dream, if you like, married to a cruel reality.

Psychoanalysis is a very different