Thomism: Substance & Accidents
Attribution of the word substance contains a whole philosophy, how we apply it will be of first importance toward coordinating our relationship with reality—lest we smuggle in some false philosophy.
As is well known, Aquinas receives and adopts the Aristotelian division of the genera of being (genera entis) into ten modes of being (modus essendi) and predication (modus praedicandi). This means that everything we recognize has or possesses being—all we say ‘is’ and is ‘what’ it is—can be categorized into one of ten categories (categoriae). The categories are mutually exclusive and jointly exhaustive, insofar as every being falls into one or other category, and all beings find their place in these categories. The categories then represent the clearly bounded modes of reality into which everything actual can be sorted, and which then perfectly corresponds to our ways of thinking and speaking about the things that are. Thus, for Thomism, at least as traditionally understood, the categories are an effective identification and sorting of all modes of existence.
The primary category is substance (substantia), literally, what ‘sub-stands’ or ‘stands-under,’ for this mode of being undergirds all other modes. Substance is the ultimate subject of being and predication, it is that to which our thought and speech primarily refers, because it is that which possesses being in a primary way. Though in contemporary thought we often attribute the word ‘substance’ to the elements of the periodic table and their correlated compounds, for an unconsidered natural scientific understanding of reality considers these elements to be primary, this presents us with a significant problem. It is a problem on two counts, because our ordinary experience of the natural world and our reasonably grounded philosophical analysis reveal the actual individual wholes of our experience (together with their essential determination) to be the primary constituents of reality. Dogs, cats, humans, these are what are primary, for both ordinary human experience and philosophical consideration perpetually testify to their primacy, and we must recognize that primacy by clearly and forthrightly attributing the word ‘substance’ to them, for only in this way will we properly signal their priority.
It turns out that how we apply the word substance really matters, for if one takes an unconsidered natural scientific standpoint, they will regard material elements and their compounds as substances, and thus as the primary building blocks of reality. But if this is the case, then everything else will turn out to be secondary, including dogs, and cats, rocks and rosebushes, and ourselves, human persons. Everything else will then turn out to be merely some complex arrangement of these material parts which bear metaphysical primacy. But these things, dogs and cats, and everything else wholly actual, including ourselves, are certainly not secondary. We give away everything if we say they are. Therefore, we simply must attribute the word substance to the actual individual wholes of our everyday ordinary experience—that is, if our philosophy is going to explain the natural world to us rather than explain it away. Our attribution of this word ‘substance’ then contains in itself a whole philosophy of being, and how we apply it will be of first importance toward coordinating our relationship to reality and how we navigate the world—lest we smuggle in a false philosophy in its wake.
The way we use words really matters, and their is arguably no more important word, at least metaphysically speaking, than substance. Their is dignity in being a substance.
Now, with this appeal in place, let us examine the ‘meat’ of Aquinas’ understanding: The category of substance admits of a distinction between what are called primary and secondary substances:
Primary substances (substantia prima) are actually existing wholes of this or that kind. Each and every primary substance is a ‘this what (hoc aliquid)’ and a ‘what is (quid est).’ The ultimate reason primary substance is primary is because it has being in itself (in virtue of itself) and not in another. Primary substance is then also the primary referent of being since everything else has being by virtue of its inherence in primary substance. Thus, simply stated, primary substances simply are, whereas all other modes of being are in their relation to primary substances; and it is because of this that primary substances are also called subsistent substances, for subsistence explicitly signifies their possession of being in virtue of themselves. And so, again, there is dignity in being a subsistent substance.
Secondary substances (substantia secunda) are the common species (and genera) of primary substances, the species (and genera) that determine their natures. These universal specific (and generic) determinations do not have actual being in separation from primary substances, and are therefore always predicated of primary substances. Yet, while they are secondary to primary substance in this way, they still merit attribution of the term substance, for they have a kind of primacy, inasmuch as every further determination of being is predicated of these grounding determinations. When we then consider them in themselves, in abstraction, they have mental, cognitional, or intentional being, while also being grounded in the divine ideas as exemplar formal causes of what is.
All other modes of being, the nine remaining categories, are then ancillary to substance, since they all have their being in substances and all are said of substances. These secondary modes of being cannot have being independent of substance but must always inhere in substance, for they have their being by virtue of the substances in which they inhere and which they further determine, while also entirely depending on this underlying substantial foundation. Therefore, following Aristotle, Aquinas calls them ‘accidental (accidentia)’ because they ‘happen in’ or ‘come along with’ substance.
The nine accidental categories include the following:
2. Quantity (quantitate): How much of a substance, its extension in place.
3. Quality (quale): How a substance is disposed or habituated.
4. Relation (ad aliquid): How a substance bears reference to (an)other substance(s).
5. Place (ubi): Where a substance is in reference to surrounding substances.
6. Time (quando): When a substance is in reference to the succession of change.
7. Posture (positio): How parts of a substance are relatively positioned.
8. Having (habitus): How a substance is externally conditioned.
9. Action (actio): The production of change by a substance.
10. Passion (passio): The reception of change by a substance.
