 Notice that a programme can make progress, both theoretically and empirically, even though every theory produced within it is refuted. A programme degenerates if its successive theories are not theoretically progressive (because it predicts no novel facts), or not empirically progressive (because novel predictions get refuted). Furthermore, and contrary to Kuhn’s idea that normally science is dominated by a single paradigm, Lakatos claimed that the history of science typically consists of competing research programmes. A scientific revolution occurs when a degenerating programme is superseded by a progressive one. It acquires hegemonic status though its rivals may persist as minority reports.