Einstein's results again turned the tables and now very few philosophers or scientists still think that scientific knowledge is, or can be, proven knowledge.

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

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

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.

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

Intellectual honesty consists in stating the precise conditions under which one will give up one's belief.

The history of mathematics, lacking the guidance of philosophy, [is] blind, while the philosophy of mathematics, turning its back on the most intriguing phenomena in the history of mathematics, is empty.