Philosophy of science without history of science is empty; history of science without philosophy of science is blind.

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

Indeed, this epistemological theory of the relation between theory and experiment differs sharply from the epistemological theory of naive falsificationism.

That sometimes clear ... and sometimes vague stuff ... which is ... mathematics.

It is not that we propose a theory and Nature may shout NO; rather, we propose a maze of theories, and Nature may shout INCONSISTENT.

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

It would be wrong to assume that one must stay with a research programme until it has exhausted all its heuristic power, that one must not introduce a rival programme before everybody agrees that the point of degeneration has probably been reached.