The business of the philosopher is well done if he succeeds in raising genuine doubt.

It is not impossible to think that the minds of philosophers sometimes act like those of other mortals, and that, having once been determined by diverse circumstances to adopt certain views, they then look for and naturally find reasons to justify these views.

All logic texts are divided into two parts. In the first part, on deductible logic, the fallacies are explained; in the second part, on inductive logic, they are committed.

Cruel persecutions and intolerance are not accidents, but grow out of the very essence of religion, namely, its absolute claims.

Again, both literature and philosophy work by appealing to certain reigning idols.

Liberalism is an attitude rather than a set of dogmas - an attitude that insists upon questioning all plausible and self-evident propositions, seeking not to reject them but to find out what evidence there is to support them rather than their possible alternatives.

If a philosophic theory is once ruled out of court, no one can tell when it will appear again.