The proving power of the intellect or the senses was questioned by the skeptics more than two thousand years ago; but they were browbeaten into confusion by the glory of Newtonian physics.

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.

The proving power of the intellect or the senses was questioned by the skeptics more than two thousand years ago; but they were browbeaten into confusion by the glory of Newtonian physics.

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

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

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

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