  Since the time of Pierre Duhem in the early twentieth century, Francis of Marchia has been known to historians as a scientist. In fact, to a large extent Marchia had gained such a reputation in his own lifetime. It is in the question commentary on the Physics of Francis Marbres (a.k.a. John the Canon; Schabel 2014) that we find him paraphrasing Marchia on future contingents, for example, and Marbres’ commentary is full of references to Marchia’s own commentaries on the Sentences and the Metaphysics (Friedman-Schabel 2006, 8–10). Looking through the titles of Marchia’s questions, one finds an abundance of scientific topics related to such things as the infinite and the psychology of willing (Friedman-Schabel, 2001). In general, Marchia displays a great interest in the causal process. One thing that helps explain his popularity among historians of medieval science, and perhaps his own interest in scientific matters, is his clear and sharp distinction between natural causation that works necessarily and the contingent causation of human and divine free will. In an influential passage containing echoes of Siger of Brabant, a passage to which Anneliese Maier first drew attention (Scriptum I, d. 36: Maier 1949; Marchia 2000), Marchia explains that there are two types of contingency in the world: first, there is contingency per se, simpliciter, positiva, and intrinseca. This is the contingency by which something is still able to occur or not occur even when all the required accidental, natural causes have been posited. There is only one source of such contingency: free will. Second, there is contingency per accidens, secundum quid, privativa, and extrinseca. This is the contingency of natural causation. A natural effect takes place as the result of many accidental causes. Some of these causes may be impeded by other natural, accidental causes, and so with respect to a small, limited number of causes a natural effect may be considered ‘contingent’. This does not mean that the natural effect is really and truly contingent without qualification in the first way, however, because if we take all of the natural effect’s causes into account, the effect will necessarily follow, or not follow, as the case may be. That is, assuming God’s contingent creation in the first place, and His ‘general influence’ that keeps the chain of causation in existence, natural causation works necessarily, and so with all of an effect’s causes taken together, what happens in nature is necessary. Of crucial important for science is Marchia’s further assertion that these ‘contingent’ effects can even be known by a created intellect. This is because the number of natural causes is not infinite. Thus a finite, created intellect can know the natural future with certainty. The only problem, says Marchia, is that we humans have a short life and an intellect that is bound with the body.