No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.
All things living are in search of a better world .
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.
The survival value of intelligence is that it allows us to exterminate a bad idea, before the idea exterminates us.
It is the rule which says that the other rules of scientific procedure must be designed in such a way that they do not protect any statement in science against falsification.
We hate the very idea that our own ideas may be mistaken, so we cling dogmatically to our conjectures.
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 only way to test a hypothesis is to look for all the information that disagrees with it.
It is wrong to ask who will rule. The ability to vote a bad government out of office is enough. That is democracy.
What really makes science grow is new ideas, including false ideas.
There will be well-testable theories, hardly testable theories, and non-testable theories. Those which are non-testable are of no interest to empirical scientists. They may be described as metaphysical.
Historically speaking all – or very nearly all – scientific theories originate from myths.
The history of science is everywhere speculative. It is a marvelous hiatory. It makes you proud to be a human being.
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.
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.
The quest for precision is analogous to the quest for certainty and both – precision and certainty are impossible to attain.
Serious rational criticism is so rare that it should be encouraged. Being too ready to defend oneself is more dangerous than being too ready to admit a mistake.
Some scientists find, or so it seems, that they get their best ideas when smoking; others by drinking coffee or whisky. Thus there is no reason why I should not admit that some may get their ideas by observing, or by repeating observations.
Better our hypotheses die for our errors than ourselves.
No book can ever be finished. While working on it we learn just enough to find it immature the moment we turn away from it.
Every genuine test of a theory is an attempt to falsify it, or to refute it.