Real Natures
On What Makes Things the Kind of Things They Are
Natures—or substantial forms, to use traditional terminology—are intelligible structures that account for the way things are. Most of the natures we’re familiar with are materialized intelligible structures (dogs, cats, trees, etc.), where the structures are repeatable (this dog, that dog, the other dog, etc.). So: I have my human nature, you have your human nature. These natures are really the same, yet numerically distinct.1
This is a reason—one of many—for why metaphysical constitution is required. There are beings constituted by their real natures and the matter structured thereby. To deny such constitution is to remove the possibility of repeatable natures, to make everything radically individual, to remove all conceptual space for real sameness that is not strict numerical identity (nominalism).
Importantly, “really the same” is not strict Leibnizian identity—it’s neither transitive nor symmetric. After all, things can be really the same thing (in being) but also really distinct. For example: the structure and the material it structures. Said differently, the structure of the thing and the thing are really the same (i.e. a wooden desk), and the material of the thing and the thing are really the same, yet the structure is not the material. Quite obviously, the structure can be lost (when the desk is destroyed) while the matter remains, whereas the matter can change while the structure persists (as in living organisms). Our material gradually shifts, yet our intelligible structure remains the same.2
There is also need for hierarchically ordered structures, reflecting different modes of being—for example, forms that constitute something as a sort of thing, and forms that further characterize what is already constituted. We know that the dog is brown by how it looks—by how it blends into the brush, say—but that does not explain how the dog is brown. To say how we know that something is charactered this or that way is, generally, uninteresting.3 Few people deny that we know things are charactered in such a way by how they look, operate, and so on. But that is just an epistemological explanation (how we know a dog is brown), which is really distinct from—and cannot replace—an adequate metaphysical explanation (how the dog actually is brown).
What ultimately needs to be answered is how things have, or derive, such a character—what accounts not just for their character, but how other things have a similar, or really the same, character. This dog has the essential character it does because of its dog nature, which is part of the larger metaphysical composite that also includes the matter structured thusly; together, and only together, can be make sense of why there is this (individual) dog (repeatable structure). But the dog has the contingent character it does—brownness—by being structured further, with another form that is itself really distinct from the most basic constituting structure and the entire composite. Hence the traditional distinction between substantial and accidental form.
Said differently, the dog is really, not just conceptually, distinct from its brownness—in this case, obviously so, because one can be a dog (even the same dog) and not be brown. Brownness can be lost for the dog, whereas dogness cannot be.
The alternatives to this account (real essentialism) are unattractive. The nominalist (at least as defined above; the term admits considerable variance in actual use) has no adequate answer to the critical question concerning real conspecificity. Nor do they have an adequate account of how things have the character they do, especially once we understand that things have characters that are mutable, with certain features constituting more of a “core” or “nucleus” than others, and how certain things can be really the same yet really distinct.4
On the other hand, there is something—perhaps not equally unattractive, but still unattractive enough—in having to go beyond the current posit and posit an independently existing realm of abstracta, properties, and so on. The position articulated here—generally one of moderate realism—seems to strike the right balance of explanatory depth and ontological modesty.
Finally, the constituent ontology articulated so far is not the result of how language happens to be used, but of what the necessary conditions must be to make sense of character, real conspecificity, identity through change, and all the rest. The modesty, meanwhile, lies in avoiding the more luscious and luxuriant forms of Platonism—positing just what one needs, and not more, and in refusing to let language become overly ontologically committing.
One of the best defenses of this view is found in Ross, James F. Thought and World: The Hidden Necessities. Notre Dame, IN: University of Notre Dame Press, 2008.
Another example: I can know a certain thing and you can know a certain thing, and what we know can be really the same thing (i.e. that some cat exists), yet your knowing is not my knowing.
Moreover, to intend not to answer these questions simply by insisting that no further ontological ground is required leaves an uncomfortable—many, including myself, would say unacceptable—plentitude of critically coherent questions unanswered).
To anticipate: I take it that for trope nominalism to do the work required, it must still, ultimately, rely upon the notion of shared—or at least repeatable, even if numerically distinct, tropal structures—which is really just a recommitment to the realism I am articulating here; or at least a sort of realism.)