Karl Popper - Theory Quotes

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As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analyzing in terms of his theory of inferiority feelings, although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. "Because of my thousandfold experience," he replied; whereupon I could not help saying: "And with this new case, I suppose, your experience has become thousand-and-one-fold."

Karl Popper
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.

Karl Popper
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.

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

Karl Popper
There are all kinds of sources of our knowledge; but none has authority … The fundamental mistake made by the philosophical theory of the ultimate sources of our knowledge is that it does not distinguish clearly enough between questions of origin and questions of validity.

Karl Popper
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.

Karl Popper
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.

Karl Popper
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.

Karl Popper
The initial stage, the act of conceiving or inventing a theory, seems to me neither to call for logical analysis nor to be susceptible of it.

Karl Popper
Darwinism is not a testable scientific theory, but a metaphysical research program.

Karl Popper
The hope of getting some argument or theory to share our responsibilities is, I believe, one of the basic motives of "scientific" ethics.

Karl Popper
We have no reason to regard the new theory as better than the old theory — to believe that it is nearer to the truth — until we have derived from the new theory new predictions which were unobtainable from the old theory (the phases of Venus.) and until we have found that these new predictions were successful.

Karl Popper
The relationship between a theory (or a statement) and the words used in its formulation is in several ways analogous to that between written words and the letters used in writing them down.

Karl Popper
In order that a new theory should constitute a discovery or a step forward it should conflict with its predecessor... it should contradict its predecessor; it should overthrow it. In this sense, progress in science — or at least a striking progress — is always revolutionary.

Karl Popper
Every "good" scientific theory is one which forbids certain things to happen; the more a theory forbids, the better it is.

Karl Popper