Karl Popper Quotes

“There are no ultimate sources of knowledge. Every source, every suggestion, is welcome; and every source, every suggestion, is open to critical examination. Except in history, we usually examine the facts themselves rather than the sources of our information.” —Karl R. Popper, Conjectures and Refutations, Ch. 2, p. 27 (1962)

“There is only one element of rationality in our attempts to know the world: it is the critical examination of our theories.” —Karl R. Popper, Conjectures and Refutations, Ch. 5, p. 151 (1962)

"It is our duty not to prophesy evil, but to fight for a better world." —Karl Popper.

“True ignorance is not the absence of knowledge, but the refusal to acquire it.” —Karl Popper.

"It is wrong to think that the task of criticism is to expose the weaknesses of those in power; its real task is to help us all to understand better the problems which we face." —Karl Popper, The Open Society and Its Enemies, Volume 2, Chapter 23

"Human mistakes are made because one can sometimes give good reasons for a thing to be true and bad reasons for a thing to be true, but never conclusive reasons for a thing to be true." —Karl Popper

"The growth of knowledge, and especially of scientific knowledge, consists in learning from our mistakes." ––Karl Popper, The Myth of the Framework.

"Science may be regarded as a growing system of problems, rather than as a system of beliefs." ––Karl Popper, The Myth of the Framework.

"If I thought of a future, I dreamt of one day founding a school in which young people could learn without boredom, and would be stimulated to pose problems and discuss them; a school in which no unwanted answers to unasked questions would have to be listened to; in which one did not study for the sake of passing examinations." ––Karl Popper, Unended Quest, 1979.

"There is only one element of rationality in our attempts to know the world: it is the critical examination of our theories. These theories themselves are guesswork. We do not know, we only guess. If you ask me, 'How do you know?' my reply would be, 'I don't; I only propose a guess. If you are interested in my problem, I shall be most happy if you criticize my guess, and if you offer counter-proposals, I in turn will try to criticize them.'" —Karl Popper, Conjectures and Refutations, Ch. 5, p. 151 (1962)

"For I believe that there is only one excuse for a lecture: to challenge. It is the only way in which speech can be better than print." —Karl Popper, Unended Quest (1992), p. 142

"The child does not wait to be taught but learns by inventing and testing its own theories about the world; education should build on this natural curiosity rather than suppress it." —Karl Popper, Objective Knowledge: An Evolutionary Approach, 1972, p. 346.

"Fallibilism is the view that all our knowledge is conjectural, and that we must always be ready to revise it in the light of new evidence; it is the recognition that we are all fallible, and that our best theories may be mistaken. This attitude is essential for the advancement of science, for it encourages a spirit of openness and criticism, rather than dogmatism." —Karl Popper, Conjectures and Refutations, p. 132–133 (1963)

"Beginning with the suppression of reason and truth, we must end with the most brutal and violent destruction of all that is human. This is the inevitable consequence of any system that seeks to control thought, to suppress dissent, to impose a single, unchallengeable doctrine." —Karl Popper, The Open Society and Its Enemies, Volume 2, (1966 ed.)

"Power without limits destroys itself and those it rules. The more absolute the authority, the more absolute the corruption. Only by keeping it in check can we preserve the open process of freedom." —Karl Popper, The Open Society and Its Enemies, Vol. 1 (1945), p. 123

"The greatest danger to democracy is the belief in the possibility of a perfect society. Democracy thrives as a process of trial and error, not as a blueprint for an unattainable ideal." —Karl Popper, The Open Society and Its Enemies, Vol. 1 (1945), p. 159

"The critical attitude, the tradition of free criticism of theories with the aim of replacing them by better ones, is the attitude which, I suggest, we should adopt towards all our theories, whether they are scientific or otherwise. It is an attitude which does not seek dogmatic certainty, but rather the growth of knowledge through the elimination of error." —Karl Popper, Conjectures and Refutations (1963, pp. 216)

Karl Popper on How We Gain Knowledge: ––Karl Popper: "People think, usually, that we acquire knowledge by opening our eyes and our ears and let the sensations stream into us, and they believe then that we record this like a camera. In my opinion, if we wish to get knowledge, we have to have a problem. It has to be knowledge of something. We have to find out something. We don't have to wait for information to stream into us, but we have to be inquisitive if we want to get knowledge. If we were passive, we would gain a confused mass of sensations or something like that, which we would hardly be able to understand and to convert into what one may call knowledge. Quite apart from that, perception is not really, in my opinion, the main source of our knowledge. The role of perception is to inform us about a momentary situation in our environment. But we couldn't really interpret our perceptions without knowing much more about our environment, namely, we know whether we are in a house or whether we are in a glacier. So we have two kinds of knowledge: this wider knowledge of a frame in which we orientate ourselves, and the momentary perception which gives us information about the situation at that particular moment. And it is only this situation in which we can use our perception. So we have theoretical knowledge and, if you like, the momentary practical challenge to our theoretical knowledge. And here comes perception in."

"Today it has become fashionable in the sciences to appeal to the specialized knowledge and authority of experts, and fashionable in philosophy to denigrate science and rationality. Oftentimes, this denigration of science and rationality is due to a mistaken theory of science and rationality — a theory which speaks of science and rationality in terms of specializations, experts, and authority. But science and rationality have really very little to do with specialization and the appeal to expert authority. On the contrary, these intellectual fashions are actually an obstacle to both. For just as the fashionable thinker is a prisoner of his fashion, the expert is a prisoner of his specialization. And it is the freedom from intellectual fashions and specializations that makes science and rationality possible." —Karl Popper, The Myth of the Framework (1994)

“Cultural relativism and the doctrine of the closed framework are serious obstacles to the readiness to learn from others. They are obstacles to the method of accepting some institutions, modifying others, and rejecting what is bad.” ––Karl Popper, The myth of the framework.