The positive heuristic of the programme saves the scientist from becoming confused by the ocean of anomalies.

Blind commitment to a theory is not an intellectual virtue: it is an intellectual crime.

Research programmes, besides their negative heuristic, are also characterized by their positive heuristic.

One may rationally stick to a degenerating research programme until it is overtaken by a rival and even after. What one must not do is to deny its poor public record... It is perfectly rational to play a risky game: what is irrational is to deceive oneself about the risk.

Man's respect for knowledge is one of his most peculiar characteristics. Knowledge in Latin is scientia, and science came to be the name of the most respectable kind of knowledge.

There is no falsification before the emergence of a better theory.

In degenerating programmes, however, theories are fabricated only in order to accommodate known facts