Karl Popper Quotes

The only way to test a hypothesis is to look for all the information that disagrees with it.

The growth of knowledge depends entirely upon disagreement.

Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society, then the tolerant will be destroyed, and tolerance with them. We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.

Ignorance is not a simple lack of knowledge but an active aversion to knowledge, the refusal to know, issuing from cowardice, pride, or laziness of mind.

True ignorance is not the absence of knowledge, but the refusal to acquire it.

The question is not how to get good people to rule; THE QUESTION IS: HOW TO STOP THE POWERFUL from doing as much damage as they can to us.

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.

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

In so far as a scientific statement speaks about reality, it must be falsifiable; and in so far as it is not falsifiable, it does not speak about reality.

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

You cannot have a rational discussion with a man who prefers shooting you to being convinced by you.

Optimism is a duty. The future is open. It is not predetermined. No one can predict it, except by chance. We all contribute to determining it by what we do. We are all equally responsible for its success.

If we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.

The defence of democracy must consist in making anti-democratic experiences too costly for those who try them; much more costly than a democratic compromise

Those who promise us paradise on earth never produced anything but a hell.

Every intellectual has a very special responsibility. He has the privilege and the opportunity of studying. In return, he owes it to his fellow men (or 'to society') to represent the results of his study as simply, clearly and modestly as he can. The worst thing that intellectuals can do - the cardinal sin - is to try to set themselves up as great prophets vis-à-vis their fellow men and to impress them with puzzling philosophies. Anyone who cannot speak simply and clearly should say nothing and continue to work until he can do so.

It can't happen here is always wrong: a dictatorship can happen anywhere.

Every solution of a problem raises new unsolved problems.

We do not know. We can only guess.

I personally call the type of government which can be removed without violence 'democracy,' and the other, 'tyranny.'.

All life is problem solving

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.

The best thing that can happen to a human being us to find a problem, to fall in love with that problem, and to live trying to solve that problem, unless another problem even more lovable appears.

It is not possible to write clearly enough to avoid being misrepresented by people who are sufficiently determined to do so.

The survival value of intelligence is that it allows us to extinct a bad idea, before the idea extincts us.