We say that a sentence is factually significant to any given person, if, and only if, he knows how to verify the proposition which it purports to express.

It is time, therefore, to abandon the superstition that natural science cannot be regarded as logically respectable until philosophers have solved the problem of induction. The problem of induction is, roughly speaking, the problem of finding a way to prove that certain empirical generalizations which are derived from past experience will hold good also in the future.

The only possible basis for a sound morality is mutual tolerance and respect: tolerance of one another’s customs and opinions; respect for one another’s rights and feelings; awareness of one another’s needs.

It seems that I have spent my entire life trying to make life more rational and that it was all wasted effort.

If the assertion that there is a god is nonsensical, then the atheist's assertion that there is no god is equally nonsensical, since it is only a significant proposition that can be significantly contradicted.

It appears, then, that ethics, as a branch of knowledge, is nothing more than a department of psychologyand sociology.

It is possible to be a meta-physician without believing in a transcendent reality; for we shall see that many metaphysical utterances are due to the commission of logical errors, rather than to a conscious desire on the part of their authors to go beyond the limits of experience.