The great scientific achievements are research programmes which can be evaluated in terms of progressive and degenerative problemshifts; and scientific revolutions consist of one research programme superceding (overtaking in progress) another. This methodology offers a new rational reconstruction of science.
Imre Lakatos (1922–1974), Hungarian philosopher of science. repr. Scientific Revolutions, pp. 107-127, ed. I. Hacking. originally published in Boston Studies in Philosophy of Science VIII, "History of Science and its Rational Reconstructions," eds. R. Buck and R. Cohen, PSA (1970).
The author's major contribution to theory of scientific methodology.