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.

It is wrong to think that belief in freedom always leads to victory; we must always be prepared for it to lead to defeat. If we choose freedom, then we must be prepared to perish along with it.

If we wish our civilization to survive we must break with the habit of deference to great men.

. . . it seems to me certain that more people are killed out of righteous stupidity than out of wickedness.

The moral decisions of others should be treated with respect, as long as such decisions do not conflict with the principle of tolerance.

I am opposed to looking upon logic as a kind of game. ... One might think that it is a matter of choice or convention which logic one adopts. I disagree with this view.

Definitions.... are never really needed, and rarely of any use