Astrologers were greatly impressed, and misled, by what they believed to be confirming evidence-so much so that they were quite unimpressed by any unfavorable evidence. Moreover, by making their interpretations and prophecies sufficiently vague they were able to explain away anything that might have been a refutation of the theory had the theory and the prophecies been more precise. In order to escape falsification they destroyed the testability of their theory. It is a typical soothsayer's trick to predict things so vaguely that the predictions can hardly fail: that they become irrefutable.

A theory that explains everything, explains nothing

Piecemeal social engineering resembles physical engineering in regarding the ends as beyond the province of technology.

I have come to the conclusion that Darwinism is not a testable scientific theory, but a metaphysical research programme.

Instead of encouraging the student to devote himself to his studies for the sake of studying, instead of encouraging in him a real love for his subject and for inquiry, he is encouraged to study for the sake of his personal career; he is led to acquire only such knowledge as is serviceable in getting him over the hurdles which he must clear for the sake of his advancement.

It must be possible for an empirical system to be refuted by experience.

You cannot have a rational discussion with a man who prefers shooting you to being convinced by you.