The Problems of Philosophy

by Bertrand Russell

Is there any knowledge in the world which is so certain that no reasonable man could doubt it?

but whoever wishes to become a philosopher must learn not to be frightened by absurdities.

belief in an independent external world.

We find this belief ready in ourselves as soon as we begin to reflect: it is what may be called an instinctive belief.

The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken.

'Laws of Thought'. They are as follows: (1) The law of identity: 'Whatever is, is.' (2) The law of contradiction: 'Nothing can both be and not be.' (3) The law of excluded middle: 'Everything must either be or not be.'

a belief for which no reason can be given is an unreasonable belief.