Experience has taught me a technique for dealing with such people [...] I counter the devotees of the Great Pyramid by adoration of the Sphinx; and the devotee of nuts by pointing out that hazelnuts and walnuts are as deleterious as other foods and only Brazil nuts should be tolerated. But when I was younger I had not yet acquired this technique, with the result that my contacts with cranks were sometimes alarming.

Our great democracies still tend to think that a stupid man is more likely to be honest than a clever man, and our politicians take advantage of this prejudice by pretending to be even more stupid than nature has made them.

In the great depression, things could only be set right by causing the idle plant to work again . . . Roosevelt . . . spent billions of public money and created a huge public debt, but by so doing he revived production and brought his country out of the depression. Businessmen, who in spite of such a sharp lesson continued to believe in old-fashioned economics, were infinitely shocked, and although Roosevelt saved them from ruin, they continued to curse him and to speak of him as 'the madman in the White House.' . . . [It's one more] striking example of inability to learn from experience.

Whether science-and indeed civilization in general-can long survive depends upon psychology, that is to say, it depends upon what human beings desire.

Philosophy arises from an unusually obstinate attempt to arrive at real knowledge. What passes for knowledge in ordinary life suffers from three defects: it is cocksure, vague and self-contradictory. The first step towards philosophy consists in becoming aware of these defects, not in order to rest content with a lazy scepticism, but in order to substitute an amended kind of knowledge which shall be tentative, precise and self-consistent.

Even in civilized mankind faint traces of monogamous instinct can be perceived.

In the first place a philosophical proposition must be general. It must not deal specially with things on the surface of the earth, or within the solar system, or with any other portion of space and time. . . . This brings us to a second characteristic of philosophical propositions, namely that they must be a priori. A philosophical proposition must be such as can neither be proved nor disproved by empirical evidence. . . . Philosophy, if what has been said is correct, becomes indistinguishable from logic as that word has now come to be used.