Plato felt that a complete reconstruction of society's political program was needed.

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.

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

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

It is clear that everybody interested in science must be interested in world 3 objects. A physical scientist, to start with, may be interested mainly in world 1 objects--say crystals and X-rays. But very soon he must realize how much depends on our interpretation of the facts, that is, on our theories, and so on world 3 objects. Similarly, a historian of science, or a philosopher interested in science must be largely a student of world 3 objects.

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 growth of knowledge depends entirely upon disagreement.