Karl Popper Quotes

“For if we are uncritical we shall always find what we want: we shall look for, and find, confirmations, and we shall look away from, and not see, whatever might be dangerous to our pet theories. In this way it is only too easy to obtain what appears to be overwhelming evidence in favour of a theory which, if approached critically, would have been refuted.” — Karl Popper, The Poverty of Historicism (1964), p. 134.

"And I do believe that very many of the statements which we hold for truths are true. I also believe that very many statements which we hold for truths are false. And I do not believe that there is a criterion to distinguish with certainty between true statements and false statements. And this is the deepest reason for the fallibility of man. This does not mean that we shouldn't try to find truths, and it does not mean that we shouldn't get nearer and nearer to the truth. It doesn't even mean that we cannot know that we have got nearer to the truths. We can know we have got nearer to the truths, but it means that we can never know that we have reached the truths." — Karl Popper

"The growth of knowledge proceeds from old problems to new problems, by means of conjectures and refutations.” –– Karl Popper, Objective Knowledge (1979),: An evolutionary approach, Revised edition, Chapter 7: Evolution and the Tree of Knowledge, p. 258.

"I believe that it would be worth trying to learn something about the world even if in trying to do so we should merely learn that we do not know much." –– Karl Popper

"Scientific research is the best method we have for obtaining information about ourselves and about our ignorance." — Karl Popper, In Search of a Better World: Lectures and Essays from Thirty Years, Routledge, 1992, p. 79.

“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)

“The first duty of every serious student is to further the growth of knowledge by participating in the search for truth — or in the search for better approximations to the truth. Of course, every student is fallible, as are even the greatest masters — everybody is bound to make mistakes, even the greatest thinkers. Although this fact should encourage us not to take our mistakes over-seriously, we must resist the temptation to look upon our mistakes leniently. The establishment of high standards by which to judge our work, and the duty to constantly raise these standards by hard work, are both indispensable. At the same time, we must constantly remind ourselves (especially in connection with the application of science) of the finitude and fallibility of our knowledge, and of the infinity of our ignorance.” — Karl R. Popper, The Myth of the Framework: In Defence of Science and Rationality, Routledge, 1994, p. 18.

“Thus I am turning the tables on those who think that observation must precede expectations and problems; and I even assert that for logical reasons, observation cannot be prior to all problems, although obviously it will often be prior to some problems—for example to those problems which arise from an observation that disappoints some expectation or refutes some theory. The fact that observation cannot precede all problems may be illustrated by a simple experiment which I wish to carry out, by your leave, with yourselves as experimental subjects. My experiment consists of asking you to observe, here and now. I hope you are all co-operating, and observing! However, I fear that at least some of you, instead of observing, will feel a strong urge to ask: ‘WHAT do you want me to observe?’            If this is your response, then my experiment was successful. For what I am trying to illustrate is that, in order to observe, we must have in mind a definite question which we might be able to decide by observation. Darwin knew this when he wrote: ‘How odd it is that anyone should not see that all observation must be for or against some view . . .’” –– Karl Popper, Objective Knowledge (1979): An evolutionary approach, Revised edition, Chapter 7: Evolution and the Tree of Knowledge, p. 259

“My answer is simple: by producing an inadequate solution, and by criticising it. Only in this way can we come to understand the problem. For to understand a problem means to understand its difficulties; and to understand its difficulties means to understand why it is not easily soluble—why the more obvious solutions do not work. We must therefore produce these more obvious solutions; and we must criticise them, in order to find out why they do not work. In this way, we become acquainted with the problem, and may proceed from bad solutions to better ones—provided always that we have the creative ability to produce new guesses, and more new guesses.” –– Karl Popper, Objective Knowledge (1972): An evolutionary approach, Revised edition, Chapter 7: Evolution and the Tree of Knowledge, p. 260

“From the point of view of objective knowledge, all theories therefore remain conjectural. From the point of view of practical life, they may be far better discussed, criticized, and tested than anything we are accustomed to act upon, and to regard as certain.” — Karl Popper, Objective Knowledge (1972)

“The method of science is the method of bold conjectures and ingenious and severe attempts to refute them.” — Karl Popper, Objective Knowledge: An Evolutionary Approach (1972)

"There are all kinds of sources of our knowledge; but none has authority." — Karl Popper.

"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.' (The latter point is highly desirable, but not indispensable; for if we fail to criticize our own theories, there may be others to do it for us.) This answer sums up a position which I propose to call 'critical rationalism". — Karl Popper, Conjectures and Refutations (1963), p. 26

"Good tests kill flawed theories; we remain alive to guess again." — Karl Popper, Objective Knowledge (1972).

“But as a rule, we soon find that our conjectures can be refuted, or that they do not solve our problem, or that they solve it only in part; and we find that even the best solutions—those able to resist the most severe criticism of the most brilliant and ingenious minds—soon give rise to new difficulties, to new problems. Thus we may say that the growth of knowledge proceeds from old problems to new problems, by means of conjectures and refutations.” –– Karl Popper, Objective Knowledge (1979),: An evolutionary approach, Revised edition, Chapter 7: Evolution and the Tree of Knowledge, p. 258.

"Whenever we propose a solution to a problem, we ought to try as hard as we can to overthrow our solution, rather than defend it. Few of us, unfortunately, practise this precept; but other people, fortunately, will supply the criticism for us if we fail to supply it ourselves." — Karl R. Popper, The Logic of Scientific Discovery, Preface to First English Edition, p. xix (1959)

"I may be wrong and you may be right, and by an effort, we may get nearer to the truth." –– Karl Popper.

"No rational argument will have a rational effect on a man who does not want to adopt a rational attitude." — Karl Popper, The Open Society and Its Enemies (1945)

"An argument which appeals to the fact that we possess knowledge or that we can learn from experience, and which concludes from this fact that knowledge or learning from experience must be possible, and further, that every theory which entails the impossibility of knowledge, or of learning from experience, must be false, may be called a ‘transcendental argument’." — Karl R. Popper, The Logic of Scientific Discovery, Appendix VII, p. 380 (1959)

"In science there is progress. That has to do with the fact that science has an aim. Science is the search for truth and its aim is the approximation to the truth." — Karl Popper, In Search of a Better World: Lectures and Essays from Thirty Years, Routledge, 1992, p. 9