According to a standard interpretation of Aristotle, a material substance, like a dog, is a hylomorphic composite of matter and form, its “essential” parts. Is such a composite some thing in addition to its essential parts as united? The moderate reductionist says “no,” whereas the anti-reductionist says “yes.” In this paper, I will clarify and defend Durand of St.-Pourçain’s surprisingly influential version of moderate reductionism, according to which hylomorphic composites are nothing over and above their essential parts and the union of those parts, where this union is explained by the presence of two modes: a mode of inherence on the side of form and a mode of substanding on the side of matter.

This paper discusses two interrelated questions about ontological commitment in the thought of Gregory of Rimini (d. 1358), questions having to do with both hylomorphic composites of matter and substantial form, and with complexe significabilia that typically obtain in cases of substance–accident composition. The first question is that of the existence of real relations: neither hylomorphic composites nor complexe significabilia require real relations tying their various co-located components together. The second is that of the reducibility of such wholes to the sum of their parts: neither hylomorphic composites nor complexe significabilia are anything other than their co-located parts. And all such items can be disunited merely by a divine volition, requiring nothing extramental added to the ontology, and no change in position.

In the late Middle Ages, there was an intense debate about the metaphysical status of artefacts, in particular about whether an artefact is a new thing over and above the natural things that make it up. Realists about artefacts argued for a positive reply. In this paper, I will examine the following objection against artefact realism raised by artefact nominalists: The making of artefacts involves nothing more than local motion of already existing natural things or their parts, and local motion by itself does not lead to the production of any new thing; therefore, the making of artefacts does not involve the production of any new thing. I will look at various attempts by realists to respond to this argument and offer one possible complication for the nominalist view.

This article contains a case study of some innovative early fourteenth-century conceptions of the temporal structure of substantial change. An important tenet of thirteenth-century scholastic hylomorphism is that substantial change is an instantaneous process. In contrast, three early fourteenth-century Aristotelian commentators, first Walter Burley and then John Buridan and Albert of Saxony, progressively develop a view on which substantial change is linked to temporal duration. This process culminated, in Buridan and Albert of Saxony, with the explicit recognition of the temporally extended nature of some (if not most) instances of substantial change. This article sheds light on this neglected episode in the history of late medieval hylomorphism taking as its point of departure these commentators’ discussions of the issue of minima naturalia, i.e., the issue of the lowest possible limit of any division of substantial forms coming about through the potentially infinite division of the matter they inform. In short: is there a piece of matter so small that no substantial form can possibly inhere in it?

This paper investigates the late medieval controversy over the causal role of substantial forms in the generation of new substances. At the beginning of the fourteenth century, when there were two basic positions in this debate (section II), an original position was defended by Walter Burley and Peter Auriol, according to which accidents alone—by their own power—can generate substantial forms (section III). The paper presents how this view was received by the next generation of philosophers, i.e., around 1350 (section IV), and how, even though some of the initial theoretical motivations for this view were quickly abandoned, the view was still defended by several philosophers in the fifteenth and sixteenth centuries (section V). It is finally shown that this theory, still discussed by Suárez and early modern scholastics, and despite being generally rejected, contributed in its own way to the evolution of hylomorphism in the late Middle Ages and, to a certain extent, its gradual decline (section VI).

In this paper, I focus on Paul of Venice’s plurality of forms and souls, i.e., his “two total souls” theory. I argue that this specific theory is a result of Paul’s reception of various positions originating from fourteenth-century Parisian philosophers like John of Jandun, the Anonymous Patar, Nicole Oresme, John Duns Scotus, and Walter Burley. By receiving these positions and by making use of merely parts of their doctrines, Paul creates a theory of the hylomorphic compound that fits well within an Aristotelian framework of an Averroistic flavor. Although his position is not Averroistic in any strict sense, it mirrors quite well the growing interest in an Averroistic interpretation of Aristotle in Padua at his time. By looking at some of his successors, such as Gaetano da Thiene, Nicoletto Vernia, and Agostino Nifo, I show that Paul is on the borderline between a traditional, scholastic philosophical psychology or hylomorphism of Parisian origin and an Averroist reading of philosophical psychology or hylomorphism, which had its promoters in fifteenth-century Padua.

In a 1642 letter to Regius, Descartes elaborates several reasons for rejecting Aristotelian substantial forms including that (1) they are explanatorily impotent, (2) they are explanatorily unnecessary, and (3) they threaten the incorporeality and immortality of the human soul. Various ideas have already been proposed as to why Descartes thought Aristotelian substantial forms are susceptible to these criticisms. Here I suggest one further such idea, centered on the ways Descartes and medieval scholastics thought substantial forms—and souls in particular—are related to their powers.

It is often thought that Aristotelian hylomorphism was undermined in the early modern era by the external challenges that alternative atomist and corpuscularian matter theories posed. This narrative neglects the fact that hylomorphism was not one homogeneous theory but a fruitful, adaptable framework that enabled scholastic Aristotelianism to continuously transform itself from within and resolve new natural philosophical, metaphysical, and theological problems. I focus on the period of the Counter-Reformation and rise of Protestant scholastic metaphysics. During this time accounting for the individuation of substances within a hylomorphic framework consistent with Aristotle’s texts, the doctrine of the Trinity, and Aristotelian physics became both urgent and more challenging. I show that Protestant scholastics who took up influential late sixteenth-century Jesuit accounts of individuation so altered the hylomorphic framework inherited from medieval philosophers that atomism appeared to at least one author as more consistent with Aristotle’s metaphysical commitments.