William Kingdon Clifford

The aim of scientific thought, then, is to apply past experience to new circumstances; the instrument is an observed uniformity in the course of events. By the use of this instrument it gives us information transcending our experience, it enables us to infer things that we have not seen from things that we have seen; and the evidence for the truth of that information depends on our supposing that the uniformity holds good beyond our experience.

Remember that [scientific thought] is the guide of action; that the truth which it arrives at is not that which we can ideally contemplate without error, but that which we may act upon without fear; and you cannot fail to see that scientific thought is not an accompaniment or condition of human progress, but human progress itself.

Into this, for good or ill, is woven every belief of every man who has speech of his fellows. A awful privilege, and an awful responsibility, that we should help to create the world in which posterity will live.

This sense of power is the highest and best of pleasures when the belief on which it is founded is a true belief, and has been fairly earned by investigation.

We may always depend on it that algebra, which cannot be translated into good English and sound common sense, is bad algebra.

It is wrong always, everywhere, and for anyone, to believe anything upon insufficient evidence.