The article is a polemical survey of twentieth- century scholarship dealing with the notion of "double truth". After 1921, Etienne Gilson argued that in the writings of Siger of Brabant - the thinker who, according to well-established tradition, had been its first proponent - there was no trace of the -"double truth". He maintained that the theory had been attributed to Siger in order to discredit him by his adversaries, such as Thomas Aquinas and Etienne Tempier, bishop of Paris. Accepted practically without exception, this thesis gradually extended to envelop all possible instances from the Middle Ages to early modernity, to the point of concluding that a "double truth" never existed. It is shown here that in 1939 Gilson himself changed his mind about Siger, but this time his argument went unheard as his 1921 thesis had by now become the conventional wisdom. It is argued, furthermore, that this striking episode was part of a more general tendency aiming to domesticate ("rehabilitate", as somebody put it) thinkers who allegedly deviated from the Christian religion.
Keywords: Faith and reason, Siger de Brabant, radical Aristotelianism, Etienne Gilson, Fernand van Steenberghen