Introduction to Scholastic Ontology


I. Constituent Ontology

A constituent ontology, as I am conceiving of it, aims at a general characterization of substances in terms of various types of constituents which are in some straightforward sense intrinsic to them and compatible with their status as unified wholes. Scholastic ontology is in this broad sense a constituent ontology.

Now every plausible ontology of material substances must acknowledge that such substances have material constituents or parts and can thus be characterized as composite in that sense. However, scholastic ontology sees the natures (or essences) of such substances, as well as their characteristics (or accidents), as individuals intrinsic to those substances and capable of existing only within singular substances. The natures of such substances constitute them as entities of a given natural kind, whereas their accidents (both those that emanate directly from the natures and those that are peculiar to particular substances within a given natural kind) are related to them by the 'transcendental' relation of inherence.

A non-constituent ontology, by contrast, aims at a general characterization of substances in terms of their relations to entities (e.g., Platonistically conceived universals or properties, including abstract essences and natures) that have their being and reality independently of those substances. These natures and characteristics of substances are in some obvious way extrinsic to them and linked to them by the relation of exemplification or participation. On such a view all individuals are in some sense lacking in intrinsic composition at any level other than that of integral parts. At the very least, this sort of ontology does not think of other sorts of composition as ontologically significant.

The recent literature on divine simplicity in analytic philosophy of religion illustrates well how skewed matters become when those who work within a non-constituent ontology try to address without adequate care or preparation relevant aspects of scholastic metaphysics. For the scholastics were able to fashion a substantive and metaphysically interesting account of the distinction between God and creatures by characterizing God as wholly simple, i.e., wholly lacking in the sorts of composition characteristic of creaturely substances. Thus, they claimed, for instance, that in God there is no composition of form and matter, of substance and accident, of esse and essentia, or of genus and difference. However, each of these claims, if transformed without due care into the framework of non-constituent ontology, leads to patent absurdities. (For an analysis of this situation I recommend Nicholas Wolterstorff, "Divine Simplicity," Philosophical Perspectives 5 (1991): 531-552.)

In what follows I will try to explain the motivations for the postulation of the various types of constituents posited by mainline Aristotelian scholastic metaphysicians.

II. Modes of Composition in Scholastic Ontology

A. Physical composition

The requirement of physical composition arises from the analysis of change. Aristotle posited three principles of change, viz., privation, form, and matter. The matter of a given change is that which perdures through the change and is modified by the change, whereas the form is the terminus ad quem of the change and the privation the terminus a quo of the change. 

In cases of qualified or accidental change, this analysis requires that there be a composition of substance and accident, where the substance is the matter of the change and the accident which comes to modify the substance is the form. This accident or accidental form is a reality (perfection, sort of being) that depends for its existence on the existence of the substance in which it inheres. Such accidents are usually taken to fall into categories along the lines suggested by Aristotle, though among the later medievals there were heated debates about the status of accidents. Ockham, for instance, saw Aristotle's categories as a classification of terms rather than of entities and went on to argue that only certain terms in the category of quality signify distinctive entities; Suarez and St. Thomas, grants a type of reality to all accidents, though Suarez assigns some the status of modes, which, unlike full-fledged accidents, are only "modally distinct" and not "really distinct" from the substances in which they inhere. (A real distinction implies separability at least by God's absolute power.) Modes are something like states of substances and have less unity and independence than do, say, qualities. In any case, the three basic types of accidental change are (i) alteration (change with respect to quality), (ii) augmentation and diminution (change with respect to quantity), and local motion (change with respect to place). All changes with respect to other categories are reducible, i.e., able to be traced back, to these three.

But Aristotle insisted, apparently in keeping with common sense but contrary to received philosophical wisdom, that at least some really real things (ousiai) could themselves come into and pass out of existence through change. If such unqualified or substantial change is possible, there must be within the relevant substances (or individual natures) a composition of (primary) matter and (substantial) form. So the same matter can successively be a constituent of different substances and even of different kinds of substances. The types of substantial change are generation and corruption. (A note on Empedocles, Anaxagoras, and the atomists).

The form/matter and substance/accident distinctions can both be seen as determinations of the more general distinction between act and potency, since in each case what we have is a determinable "matter" (a potentiality) being determined or actualized or brought to completion by a determinant "form" (an actuality), which is the terminus of the change.

Aquinas's distinction between being (esse) and essence is yet another instance of this general distinction between act and potency, one that is meant to accommodate, contrary to received philosophical wisdom, the possibility of an exercise of efficient causality that is not a modification of an existing matter or substratum but is instead a creation ex nihilo of a substance with all its accidents (essentia). In this case the notion of a principle of potentiality is stretched a bit, since this principle does not exist prior to the exercise of efficient causality. Nonetheless, Aquinas and his followers insist that the distinction between esse and essence is a real distinction (in his sense of 'real distinction', which does not involve separability) on a par with the distinctions between substance and accident and between form and matter. (Suarez takes this distinction to be a conceptual distinction with a foundation in reality, but this difference is not of present concern to us.)

    Thus we have the following:
Type of Causality Act (Passive) Potency




unqualified change: 
generation & corruption
(substantial) form (primary) matter
qualified change: 
alteration & augmentation/diminution
& local motion 
accident  substance 
B. Logical (alternatively: metaphysical) composition 
    The postulation of modes of physical composition arises from the analysis of change; there is another sort of composition, the postulation of which arises from broadly scientific considerations. If we think of scientific theorizing as beginning with a taxonomy of natural kinds arranged according to species and genus (reminiscent of Aristotle's category of substance), and if we think of the goal of scientific inquiry as objective knowledge of the natures of physical substances, then we will naturally ask about the metaphysical grounds for our use of natural kinds terms, their definitions, and predications in which such terms appear as the subject and various (discovered) properties that 'emanate from' the relevant natures or essences appear as predicates, e.g., 'Salt is soluble in water'. Such statements (or 'laws') are in some obvious sense about universals or common natures rather than primarily about singulars; or at least this much is true: If George is a chunk of salt, then George is soluble by virtue of its being constituted as a member of the natural kind salt.

    Now all the scholastics agree that each secondary-substance or natural kind term has a composite definition that signals similarities among natural kinds as well as differences. For instance, both angels and aardvarks are substances, but the former are immaterial whereas the latter are material. The question then is: Is there a distinctive metaphysical constituent of a substance corresponding to each element in its definition? To take the simple hackneyed example, is there within a human being a distinctive 'metaphysical' constituent corresponding to each of the following natural-kind terms: 'substance', 'body' ('material substance'), 'living substance', 'sentient substance' ('animal'), 'rational', and, finally, 'human being' itself?

    Duns Scotus, for one, argued that there must be distinctive constituents of this sort (he called them 'formalities') if scientific methodology and theories are to be well-grounded. This is why he thought of them as 'metaphysical' constituents and then was faced with the problem of relating these metaphysical constituents to the corresponding physical constituents (matter/form) of the same substance. Also, Scotus thought that among the metaphysical constituents or formalities of a given substance there must be an individuator or individual difference that accounts for that substance's metaphysical distinctness from the other members of the same lowest-level species.

    Most other scholastics, by contrast, deny that substances have distinctive metaphysical constituents in addition to their physical constituents. According to them, the problem is to show how the various logical or conceptual constituents of natural kind concepts and their definitions are related to the physical constituents of the relevant substances. How, for instance, are distinctions like matter/form and substance/accident related to concepts of genus, species, and difference? And in the background is the question that held Aristotle's attention in the impenetrable middle books of the Metaphysics, viz., how can entities that exhibit these various modes of composition have the unity characteristic of primary substances?

    With this background we are ready to look at the first two sections of Disputation 5, in which Suarez characterizes singular or individual unity and then asks what this sort of unity adds to the common nature in such a way as to compose with that common nature a singular substance.

    Alfred J. Freddoso
    University of Notre Dame