Karl Popper Quotes

The doubter is a true man of science: he doubts only himself and his interpretations, but he believes in science.

When scientifically investigating the natural world, the only thing worse than a blind believer is a seeing denier.

It is a mistake to believe that science consists in nothing but conclusively proved propositions, and it is unjust to demand that it should. It is a demand made by those who feel a craving for authority in some form to replace the religious catechism by something else, even a scientific one.

The scientific tradition is distinguished from the pre-scientific tradition by having two layers. Like the latter, it passes on its theories; but it also passes on a critical attitude towards them.

In science , all conclusions are provisional, subject to new evidence and better arguments, the very antithesis of religious faith.

The public has a distorted view of science because children are taught in school that science is a collection of firmly established truths. In fact, science is not a collection of truths. It is a continuing exploration of mysteries.

A theory is something nobody believes, except the person who made it. An experiment is something everybody believes, except the person who made it.

If experiments are performed thousands of times at all seasons and in every place without once producing the effects mentioned by your philosophers, poets, and historians, this will mean nothing and we must believe their words rather than our own eyes?

Science is a mechanism, a way of trying to improve your knowledge of nature. It's a system for testing your thoughts against the universe, and seeing whether they match.

Another of the qualities of science is that it teaches the value of rational thought, as well as the importance of freedom of thought; the positive results that come from doubting that all the lessons are true... Learn from science that you must doubt the experts. As a matter of fact, I can also define science another way: Science is the belief in the ignorance of experts.

If we teach only the findings and products of science - no matter how useful and even inspiring they may be - without communicating its critical method, how can the average person possibly distinguish science from pseudoscience?

Imagination should give wings to our thoughts but we always need decisive experimental proof, and when the moment comes to draw conclusions and to interpret the gathered observations, imagination must be checked and documented by the factual results of the experiment.

Now is the time for everyone who believes in the rule of reason to speak up against pathological science and its purveyors.

Hope is easy; knowledge is hard. Science is the one domain in which we human beings make a truly heroic effort to counter our innate biases and wishful thinking. Science is the one endeavor in which we have developed a refined methodology for separating what a person hopes is true from what he has good reason to believe.

Scientists who think science consists of unprejudiced data-gathering without speculation are merely cows grazing on the pasture of knowledge.

[Modern science] passed through a long period of uncertainty and inconclusive experiment, but as the instrumental aids to research improved, and the results of observation accumulated, phantoms of the imagination were exorcised, idols of the cave were shattered, trustworthy materials were obtained for logical treatment, and hypotheses by long and careful trial were converted into theories.

As a scientist, I don't believe anything. Science shouldn't use the word belief. There are things more likely and less likely. Science can say nothing with absolute certainty.

The role of science is to be systematic, to be accurate, to be orderly, but it certainly is not to imply that the aggregated, successful hypotheses of the past have the kind of truth that goes into a number system.

It is a very long and very difficult road from a fact to a conclusion. But it is a million times longer from a theory to a fact.

Following Korzybski, I put things in probabilities, not absolutes... My only originality lies in applying this zetetic attitude outside the hardest of the hard sciences, physics, to softer sciences and then to non-sciences like politics, ideology, jury verdicts and, of course, conspiracy theory.

A single test which proves some piece of theory wrong is more valuable than a hundred tests showing that idea might be true.

As time passed I became an avid reader of popular scientific books, wanting to know as much as I could about the world in which I lived. Gradually I began to see a pattern of nonsense in much scientific writing. Scientific explanations given regarding the origins or functioning of various phenomena simply didn't make sense.

Science ... looks skeptically at all claims to knowledge, old and new. It teaches not blind obedience to those in authority but to vigorous debate, and in many respects that's the secret of its success.

But what a weak barrier is truth when it stands in the way of an hypothesis!

At the heart of science is an essential balance between two seemingly contradictory attitudes-an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.