Karl popper

The use of violence is justified only under a tyranny which makes reforms without violence impossible, and should have only one aim, that is, to bring about a state of affairs which makes reforms without violence possible.

No number of sightings of white swans can prove the theory that all swans are white. The sighting of just one black one may disprove it.

Reason like science, grows by way of mutual criticism; the only possible way of planning its growth is to develop those institutions that safeguard. the freedom of thought

In my view, aiming at simplicity and lucidity is a moral duty of all intellectuals: lack of clarity is a sin, and pretentiousness is a crime.

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.

Science is perhaps the only human activity in which errors are systematically criticized and, in time, corrected.

A rationalist is simply someone for whom it is more important to learn than to be proved right; someone who is willing to learn from others - not by simply taking over another's opinions, but by gladly allowing others to criticize his ideas and by gladly criticizing the ideas of others

It is wrong and dangerous to extol freedom by telling people that they will certainly be all right once they are free. The most we can say of democracy or freedom is that they give our personal abilities a little more influence on our well-being.

It is impossible to speak in such a way that you cannot be misunderstood.

It is easy to obtain confirmations, or verifications, for nearly every theory-if we look for confirmations. Confirmations should count only if they are the result of risky predictions... A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice. Every genuine test of a theory is an attempt to falsify it, or refute it.

Rationalism is an attitude of readiness to listen to contrary arguments and to learn from experience... of admitting that "I may be wrong and you may be right and, by an effort, we may get nearer the truth."

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 favor of a theory which, if approached critically, would have been refuted.

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.

Instead of encouraging the student to devote himself to his studies for the sake of studying, instead of encouraging in him a real love for his subject and for inquiry, he is encouraged to study for the sake of his personal career; he is led to acquire only such knowledge as is serviceable in getting him over the hurdles which he must clear for the sake of his advancement.

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.

Every discovery contains an irrational element or a creative intuition.

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

It is wrong to think that belief in freedom always leads to victory; we must always be prepared for it to lead to defeat. If we choose freedom, then we must be prepared to perish along with it.

If we wish our civilization to survive we must break with the habit of deference to great men.

All we can do is search for the falsity content in our best theory.

The belief in a political Utopia is especially dangerous. This is possibly connected with the fact that the search for a better world, like the investigation of our environment, is (if I am correct) one of the oldest and most important of all the instincts.

The difference between the amoeba and Einstein is that, although both make use of the method of trial and error elimination, the amoeba dislikes erring while Einstein is intrigued by it.

The attempt to make heaven on earth invariably produces hell.

We have become makers of our fate when we have ceased to pose as its prophets.

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

It is wrong to ask who will rule. The ability to vote a bad government out of office is enough. That is democracy.

Propose theories which can be criticized. Think about possible decisive falsifying experiments-crucial experiments. But do not give up your theories too easily-not, at any rate, before you have critically examined your criticism.

The true Enlightenment thinker, the true rationalist, never wants to talk anyone into anything. No, he does not even want to convince; all the time he is aware that he may be wrong. Above all, he values the intellectual independence of others too highly to want to convince them in important matters. He would much rather invite contradiction, preferably in the form of rational and disciplined criticism. He seeks not to convince but to arouse - to challenge others to form free opinions.

Every genuine test of a theory is an attempt to falsify it, or to refute it.

The conspiracy theory of society... comes from abandoning god and then asking: "Who is in his place"

For myself, I am interested in science and in philosophy only because I want to learn something about the riddle of the world in which we live, and the riddle of man's knowledge of that world. And I believe that only a revival of interest in these riddles can save the sciences and philosophy from an obscurantist faith in the expert's special skill and in his personal knowledge and authority.

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

The game of science is, in principle, without end. He who decides one day that scientific statements do not call for any further test, and that they can be regarded as finally verified, retires from the game.

We should realize that, if [Socrates] demanded that the wisest men should rule, he clearly stressed that he did not mean the learned men; in fact, he was skeptical of all professional learnedness, whether it was that of the philosophers or of the learned men of his own generation, the Sophists. The wisdom he meant was of a different kind. It was simply the realization: how little do I know! Those who did not know this, he taught, knew nothing at all. This is the true scientific spirit.

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.

Nature consists of facts and of regularities, and is in itself neither moral nor immoral. It is we who impose our standards upon nature, and who in this way introduce morals into the natural world, in spite the fact that we are part of this world. We are products of nature, but nature has made us together with our power of altering the world, of foreseeing and of planning for the future, and of making far-reaching decisions for which we are morally responsible. Yet, responsibility, decisions, enter the world of nature only with us

In point of fact, no conclusive disproof of a theory can ever be produced; for it is always possible to say that the experimental results are not reliable or that the discrepancies which are asserted to exist between the experimental results and the theory are only apparent and that they will disappear with the advance of our understanding. If you insist on strict proof (or strict disproof) in the empirical sciences, you will never benefit from experience, and never learn from it how wrong you are.

Our aim must be to make our successive mistakes as quickly as possible. To speed up evolution.

. . . it seems to me certain that more people are killed out of righteous stupidity than out of wickedness.

Every solution of a problem raises new unsolved problems.

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

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

Astrologers were greatly impressed, and misled, by what they believed to be confirming evidence-so much so that they were quite unimpressed by any unfavorable evidence. Moreover, by making their interpretations and prophecies sufficiently vague they were able to explain away anything that might have been a refutation of the theory had the theory and the prophecies been more precise. In order to escape falsification they destroyed the testability of their theory. It is a typical soothsayer's trick to predict things so vaguely that the predictions can hardly fail: that they become irrefutable.

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 'back to nature' or 'forward 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.

It is part of my thesis that all our knowledge grows only through the correcting of our mistakes.

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

The Conspiracy Theory of Society... [is] a typical result of the secularization of a religious superstition. The belief in the Homeric gods whose conspiracies explain the history of the Trojan War is gone. The gods are abandoned. But their place is filled by powerful men or groups - sinister pressure groups whose wickedness is responsible for all the evils we suffer from - such as the Learned Elders of Zion, or the monopolists, or the capitalists, or the imperialists.

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.

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.

Bold ideas, unjustified anticipations, and speculative thought, are our only means for interpreting nature: our only organon, our only instrument, for grasping her. And we must hazard them to win our prize. Those among us who are unwilling to expose their ideas to the hazard of refutation do not take part in the scientific game.

[Great scientists] are men of bold ideas, but highly critical of their own ideas: they try to find whether their ideas are right by trying first to find whether they are not perhaps wrong. They work with bold conjectures and severe attempts at refuting their own conjectures.

Science must begin with myths, and with the criticism of myths.

We have the right not to tolerate the intolerant. We should tolerate even them whenever we can do so without running a great risk; but the risk may become so great that we cannot allow ourselves the luxury.

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.

Science does not rest upon solid bedrock. The bold structure of its theories rises, as it were, above a swamp. It is like a building erected on piles. The piles are driven down from above into the swamp, but not down to any natural or 'given' base; and if we stop driving the piles deeper, it is not because we have reached firm ground. We simply stop when we are satisfied that the piles are firm enough to carry the structure, at least for the time being.

The metaphysical doctrine of determinism simply asserts that all events in this world are fixed, or unalterable, or predetermined. It does not assert that they are known to anybody, or predictable by scientific means. But it asserts that the future is as little changeable as is the past. Everybody knows what we mean when we say that the past cannot be changed. It is in precisely the same sense that the future cannot be changed, according to metaphysical determinism.

I see now more clearly than ever before that even our greatest troubles spring from something that is [as] admirable and sound as it is dangerous – from our impatience to better the lot of our fellows.

We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant.

There is an almost universal tendency, perhaps an inborn tendency, to suspect the good faith of a man who holds opinions that differ from our own opinions. It obviously endangers the freedom and the objectivity of our discussion if we attack a person instead of attacking an opinion or, more precisely, a theory.

Our knowledge can only be finite, while our ignorance must necessarily be infinite.

When we enter a new situation in life and are confronted by a new person, we bring with us the prejudices of the past and our previous experiences of people. These prejudices we project upon the new person. Indeed, getting to know a person is largely a matter of withdrawing projections; of dispelling the smoke screen of what we imagine he is like and replacing it with the reality of what he is actually like.

I don't know whether God exists or not. ... Some forms of atheism are arrogant and ignorant and should be rejected, but agnosticism—to admit that we don't know and to search—is all right. ... When I look at what I call the gift of life, I feel a gratitude which is in tune with some religious ideas of God. However, the moment I even speak of it, I am embarrassed that I may do something wrong to God in talking about God.

We know a great deal, but our ignorance is sobering and boundless. With each step forward, with each problem which we solve, we not only discover new and unsolved problems, but we also discover that where we believed that we were standing on firm and safe ground, all things are, in truth, insecure and in a state of flux.

My thesis is that what we call 'science' is differentiated from the older myths not by being something distinct from a myth, but by being accompanied by a second-order tradition-that of critically discussing the myth. ... In a certain sense, science is myth-making just as religion is.

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.

Evolution is not a fact. Evolution doesn't even qualify as a theory or as a hypothesis. It is a metaphysical research program, and it is not really testable science.

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

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.

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.

I have learned more from Hayek than from any other living thinker, except perhaps Alfred Tarski - but not even excepting Russell.

no matter how many instances of white swans we may have observed, this does not justify the conclusion that all swans are white.

It is not his possession of knowledge, of irrefutable truth, that makes the man of science, but his persistent and recklessly critical quest for truth.

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.

I have insisted that we must be tolerant. But I also believe that this tolerance has its limits. We must not trust those anti-humanitarian religions which not only preach destruction but act accordingly. For if we tolerate them, then we become ourselves responsible for for their deeds.

Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.

We do not know anything - this is the first. Therefore, we should be very modest - this is the second. Not to claim that we do know when we do not - this is the third. That's the kind of attitude I'd like to popularize. There is little hope for success.

Simple statements are to be prized more highly than less simple ones because they tell us more; because their empirical content is greater; and because they are better testable.

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

I may be wrong and you may be right, and by an effort, we may get nearer to the truth

There is no pure, disinterested, theory-free observation.

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

We do not know. We can only guess.

The future is always present, as a promise, a lure and a temptation.

Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship. We should replace it by a more modest and more realistic principle - the principle that the fight against avoidable misery should be a recognized aim of public policy, while the increase of happiness should be left, in the main, to private initiative.

The open society is one in which men have learned to be to some extent critical of taboos, and to base decisions on the authority of their own intelligence.

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

Contrary to the outstanding work of art, outstanding theory is susceptible to improvements.

The history of science, like the history of all human ideas, is a history of irresponsible dreams, of obstinacy, and of error. But science is one of the very few human activities-perhaps the only one-in which errors are systematically criticized and fairly often, in time, corrected. This is why we can say that, in science, we often learn from our mistakes, and why we can speak clearly and sensibly about making progress there. In most other fields of human endeavour there is change, but rarely progress ... And in most fields we do not even know how to evaluate change.

We never know what we are talking about.

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

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.

I have spoken to Einstein and he admitted to me that his theory was in fact no different from the one of Parmenides.

What really makes science grow is new ideas, including false ideas.

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

There is no history of mankind, there are only many histories of all kinds of aspects of human life. And one of these is the history of political power. This is elevated into the history of the world.

A theory that explains everything, explains nothing

The genuine rationalist does not think that he or anyone else is in possession of the truth; nor does he think that mere criticism as such helps us achieve new ideas. But he does think that, in the sphere of ideas, only critical discussion can help us sort the wheat from the chaff.

Appealing to his [Einstein's] way of expressing himself in theological terms, I said: If God had wanted to put everything into the universe from the beginning, He would have created a universe without change, without organisms and evolution, and without man and man's experience of change. But he seems to have thought that a live universe with events unexpected even by Himself would be more interesting than a dead one.

All things living are in search of a better world .

I think that there is only one way to science - or to philosophy, for that matter: to meet a problem, to see its beauty and fall in love with it; to get married to it and to live with it happily, till death do ye part - unless you should meet another and even more fascinating problem or unless, indeed, you should obtain a solution. But even if you do obtain a solution, you may then discover, to your delight, the existence of a whole family of enchanting, though perhaps difficult, problem children, for whose welfare you may work, with a purpose, to the end of your days.

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

We must plan for freedom, and not only for security, if for no other reason than only freedom can make security more secure.

Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now. Our fellow men have a claim to our help; no generation must be sacrificed for the sake of future generations.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.

The quest for precision is analogous to the quest for certainty and both - precision and certainty are impossible to attain.

Why do I think that we, the intellectuals, are able to help? Simply because we, the intellectuals, have done the most terrible harm for thousands of years. Mass murder in the name of an idea, a doctrine, a theory, a religion - that is all "our" doing, "our" invention: the invention of the intellectuals. If only we would stop setting man against man - often with the best intentions - much would be gained. Nobody can say that it is impossible for us to stop doing this.

Philosophy is a necessary activity because we, all of us, take a great number of things for granted, and many of these assumptions are of a philosophical character; we act on them in private life, in politics, in our work, and in every other sphere of our lives -- but while some of these assumptions are no doubt true, it is likely, that more are false and some are harmful. So the critical examination of our presuppositions -- which is a philosophical activity -- is morally as well as intellectually important.

A system is empirical or scientific only if it is capable of being tested by experience. These considerations suggest that not the verifiability but the falsifiability of a system is to be taken as a criterion of demarcation... It must be possible for an empirical or scientific system to be refuted by experience.

Thus science must begin with myths, and with the criticism of myths; neither with the collection of observations, nor with the invention of experiments, but with the critical discussion of myths, and of magical techniques and practices.

A theory is just a mathematical model to describe the observations.

All life is problem solving

Science is not a system of certain, or -established, statements; nor is it a system which steadily advances towards a state of finality... And our guesses are guided by the unscientific, the metaphysical (though biologically explicable) faith in laws, in regularities which we can uncover-discover. Like Bacon, we might describe our own contemporary science-'the method of reasoning which men now ordinarily apply to nature'-as consisting of 'anticipations, rash and premature' and as 'prejudices'.

If you know that things are bound to happen whatever you do, then you may feel free to give up the fight against them.

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.

We do not choose political freedom because it promises us this or that. We choose it because it makes possible the only dignified form of human coexistence, the only form in which we can be fully responsible for ourselves. Whether we realize its possibilities depends on all kinds of things — and above all on ourselves.

A rationalist, as I use the word, is a man who attempts to reach decisions by argument and perhaps, in certain cases, by compromise, rather than by violence. He is a man who would rather be unsuccessful in convincing another man by argument than successful in crushing him by force, by intimidation and threats, or even by persuasive propaganda.

The war of ideas is a Greek invention. It is one of the most important inventions ever made. Indeed, the possibility of fighting with with words and ideas instead of fighting with swords is the very basis of our civilization, and especially of all its legal and parliamentary institutions.

I think that we shall have to get accustomed to the idea that we must not look upon science as a 'body of knowledge,' but rather as a system of hypotheses; that is to say, as a system of guesses or anticipations which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know they are 'true' or 'more or less certain' or even 'probable.'

Historically speaking all - or very nearly all - scientific theories originate from myths.

We all remember how many religious wars were fought for a religion of love and gentleness; how many bodies were burned alive with the genuinely kind intention of saving souls from the eternal fire of hell.

The growth of knowledge depends entirely upon disagreement.

A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.

No particular theory may ever be regarded as absolutely certain.... No scientific theory is sacrosanct.

We hate the very idea that our own ideas may be mistaken, so we cling dogmatically to our conjectures.

There is no history, only histories.

Author details

Karl Popper: Biography and Life Work

Karl Popper is recognized for significant cultural contributions. The story of Karl Popper began on 28 July 1902 in Vienna, Austria-Hungary. The legacy of Karl Popper continues today, following their passing on 17 September 1994 in London, England.

Sir Karl Raimund Popper CH FRS FBA (28 July 1902 – 17 September 1994) was an Austrian–British philosopher, academic and social commentator . One of the 20th century's most influential philosophers of science , Popper is known for his rejection of the classical inductivist views on the scientific method in favour of empirical falsification made possible by his falsifiability criterion , and for founding the Department of Philosophy at the London School of Economics and Political Science . According to Popper, a theory in the empirical sciences can never be proven, but it can be falsified, meaning that it can (and should) be scrutinised with decisive experiments. Popper was opposed to the classical justificationist account of knowledge, which he replaced with "the first non-justificational philosophy of criticism in the history of philosophy", namely critical rationalism .

Legacy and Personal Influence

Personally, Karl Popper was married to Josefine Anna Henniger.

Philosophical Views and Reflections

The creation–evolution controversy raised the issue of whether creationistic ideas may be legitimately called science. In the debate, both sides and even courts in their decisions have invoked Popper's criterion of falsifiability (see Daubert standard ). In this context, passages written by Popper are frequently quoted in which he speaks about such issues himself. For example, he famously stated " Darwinism is not a testable scientific theory, but a metaphysical research program—a possible framework for testable scientific theories."

A complete list of Popper's writings is available as part 1.1 of the International personal bibliography of Karl R. Popper on the website of Karl Popper Archives at the University of Klagenfurt (see also External links ).

EQ
Empery Quotes
Inspire · Reflect · Repeat