 Dear’s study (1988) similarly insists on the deliberately “un-revolutionary” character of Mersenne’s contribution to the “scientific revolution”. Mersenne never chose to range himself against Aristotelianism, never cast himself as an innovator. His agenda is formulated in a preexisting philosophical idiom (the “language of the schools”), and his ideas display a “borrowed coherence” rather than an intrinsic one. Mersenne was not a positivist avant la lettre; he admitted that God knows what man cannot verify, that natural kinds exist in nature, that things do have essential definitions. His “skeptical” approach to physics is not so much a watered-down Pyrrhonism intended to show the inconclusiveness of natural philosophical demonstration, as it is an instrument to recommend mathematical sciences as an anchor of certainty, where ordinary natural philosophy stays in doubt and can only be defended in a probabilistic way. When Mersenne confesses that many questions cannot he determined, he is not proposing to suspend judgment but rather to formulate a probable judgment by choosing the most persuasive opinions. This “probabilism” is, according to Dear, a legacy of humanist and Ciceronian dialectics, and it remained constantly present in Mersenne’s work, even though, on some questions the weight of probabilities has changed. This was particularly the case for the Copernican opinion. Judging it very unlikely in L’Usage de la raison and in the Quaestiones, Mersenne eventually recognized that it was the opinion best suited to the phenomena observed and therefore the most probable. However, God’s freedom being never constrained, Mersenne could accept with relative equanimity the final judgment of the Church. In his Questions théologiques, he was to publish a French translation of the inquisitorial condemnation and of Galileo’s abjuration.