Metaphysical Taxonomy
Metaphysical Taxonomy
What are the most fundamental kinds of things in nature? What are the ultimate natural kinds? A glance at the history of human thought reveals three recurring suggestions: mathematical, material, and mental—the three M’s. Some thinkers have picked one category as basic: Pythagoras picked mathematics, Hobbes picked matter, Berkeley picked mind—along with countless other like-minded theorists. Reality seems to divide into these three great categories of being, the Holy Trinity of ontology. They may admit of subdivision, but they have seemed to many people to exhaust the totality of what is. What else could there be? Don’t these three exhaust the possibilities—are there even possible universes that contain additional basic ontological categories? But actually, this is far from clear, and it is an interesting question why the Trinity should have such a stranglehold on the philosophical mind. First, one might wonder, in Aristotelian spirit, whether to include the biological realm as basic: if it is irreducible to the physical (whatever exactly that is), shouldn’t it be accorded its own ontological category, united around the ideas of purpose, growth, reproduction, and other mainstays of biological science? Certainly, many thinkers have found in the animate world a new level of being—the living, the vital, the goal-directed. But can’t we go further: what about necessity and possibility? These are not the same as mere actualities, whether mathematical, material or mental; they are a different kind of kind—the modal kind. They comprise an additional level of fact. Possible worlds metaphysics dramatizes their unique mode of existence. Logical space constitutes its own realm of being. But once we have accepted that, we should consider morality—isn’t it also a further sphere of existence? Where is right and wrong, good and evil, in the categories hitherto listed? Nowhere, so we need to recognize an additional type of fact. We now have five M’s altogether, the latter two (modal and moral) being curiously neglected by our obsession with the Big Three. Is that all? What about the musical realm (back to Pythagoras)? A good case can be made (but I won’t make it here) that music is a separate and irreducible kind of thing, an extra layer of nature. It seems to be so, since we treat it as a domain of interest in its own right, with its own place in our lives, and even a systematic theory behind it. (Then what of painting, sculpture, poetry, the novel, film? Shouldn’t we include the aesthetic realm?)
Some have suggested other fundamental kinds: history (Hegel, Collingwood), the deed or process (Wittgenstein, Whitehead), spirit or energy (New Age philosophy), the logical (Frege, Russell), the textual (Derrida), the conventional or cultural (anthropology). These are all flaky to one degree or another[1] and I mention them only for the sake of completeness (and to suggest a specious tolerance). But they illustrate the possibility of conceptual constructions that attempt to look beyond the usual categories. They are not part of commonsense, even implicitly, but rather philosophical speculations, well-founded or not. They are by no means as entrenched as the categories cited earlier. They tend to be exaggerated versions of the other more recognized areas of thought. I won’t consider them further.
Why don’t the categories I have added to the usual trinity get a look-in? Because it tends to be thought that they are reducible to the others, explicable in their terms. The modal is thought to be physical or mental in some way (the laws of physics, a projection of our attitudes); the moral is taken to be a reflection of biology or human desires; the musical is viewed as a combination of mathematics and psychology. I think none of these proposals is any more plausible than attempts to reduce the Big Three to each other (materialism, idealism, and Platonism), but I won’t argue this here. Such reductive attempts are really reflections of the hold of the Big Three, which stems from tradition and a lack of imagination. I favor what may be called pluralist realism: each category corresponds to a particular sector of reality, and the sectors add up to at least six. This contrasts with such doctrines as reductive anti-realism, eliminative materialism, solipsistic idealism, physicalist structuralism, deconstructive textualism, etc. It holds that reality (nature, what is) consists of a variety of different kinds of thing (entity, property, fact) with different natures (constitutive attributes): material, mathematical, mental, modal, moral, and musical, maybe more (not all beginning with “m”). Why just these—are there possible worlds containing more, possibly undreamt of by us? I don’t want to rule that out, though I confess that nothing comes to mind. Maybe there are only so many basic metaphysical kinds that nature—any nature—could contain (it would be nice if there were exactly ten). I don’t want to say (in the manner of Wittgenstein) that there are an unlimited number of possible basic natural metaphysical kinds, as if a few thousand might someday appear, evolving like species. I am not that profligate (though three seems too stingy for my taste). Let’s start with the six M’s and see how far that takes us.
We should consider whether our basic categories admit of internal subdivision. There does seem to be something of a pattern here, though it falls short of the mystically significant (so not like the venerable “music of the spheres” and other astronomical fancies). Thus, the material divides into matter proper, on the one hand, and forces and fields, on the other; the mind divides into the experiential and the dispositional; the abstract divides into the propositional and the objectual; the modal divides into the necessary and the contingent; the moral divides into the consequential and the deontological; the musical divides into rhythm and melody. So, our six categories each divide into two (with further subdivisions possible), making twelve categories altogether. And yes, there were twelve apostles, standing in one-one correspondence with the basic categories of reality; clearly a message from God encoded into the book of nature… But let’s not go there—we know where it will lead us (into the ravings of medieval scientist-religionists). Let’s just say that reality consists of a nice round dozen basic metaphysical natural kinds, which provide the foundations of all there is (or possibly could be). We can call this the Twelvefold Way (with tongue resting comfortably in cheek). Our metaphysical taxonomy is now complete.[2]
[1] I make an exception for the logical, though that too can easily turn flaky.
[2] See how far we have come from old-fashioned anti-metaphysical positivism, which forbade all such speculations as I have freely engaged in. The amazing thing is that this kind of thinking is possible at all; and they wanted to put a stop to it!

Excellent essay. I’ve been thinking the same thing for a while now, though you explain and develop it much better than I would have. I think that you argue very much the same thing in Basic Structures of Reality with regard to the material (physical) itself. It’s not just a homogeneous blob, as physicalists imply, but all sorts of different things that are irreducible to each other: electrons, protons, neutrons, forces, fields, etc. And now we know (thanks to scientists) that even all this stuff is only 5% of the observable universe; the rest is dark matter and dark energy. (And who knows if there is yet other stuff beyond the (a) observable (b) universe?) I’m sure we will some day discover that these things themselves break down into metaphysically distinct parts as well.
Given all this, it is amazing to me that many/most metaphysicians and philosophers of mind still adhere to the materialist/physicalist dogma that everything reduces to matter in motion. Though they would deny it, I’m guessing this worldview ultimately derives from the western turn to monotheism: there must be only one divine being, not many. They just replaced divine being with being itself.
Good analogy: polytheism was always better than monotheism. Materialism is a type of monotheism of the secular in the minds of its adherents. I am a “polyrealist”.
Hope to see further development of polyrealism. I predict that one thing that won’t change is the unstoppable reductionist drive of the ruling classes of professional philosophers, “scientistically” oriented scientists and administrators serving the elites. To clarify, despite this language, I am not a closet Marxist.
The older I get the more useless they seem to me. A joke: “I am completely against capital punishment, except of course for university administrators”.
1. What is objectual abstract ? give an example . It seems to be paradoxical ! abstract is not concrete ,versus it !
2. is the modal kind , the same as the logical kind ?
Numbers are abstract objects, in contrast to propositions. The modal is more general than the logical and not all of logic is modal.
isn’t better to say the aesthetical instead of musical ?
I think the musical is a special kind of aesthetic because of its formal structure (scales etc.).
true, it is “a special kind of aesthetic ” but aes. Is more general and fundamental than mus. and therefore more appropriate for taxonomy . isn’t it true ?
The question is whether the arts are metaphysically fundamental and irreducible: that is not so clear. Does the novel correspond to an aspect of reality in the way the mental does?
Would you say your taxonomy is very much grounded in what it’s like to be a human? Would philosopher bats or whales (or some hybrid liquid-gaseous-electrical being that undergoes phase-transitions, evolved in some very different environment) have a different taxonomy? What type or scope of claims can a metaphysics really make?
I am a realist about each category, so not projections of our nature.
Can this taxonomy be understood as enumerating the various media in which our activities participate, or, in some cases, the “substances” (not implying a material nature) which our activities fashion?
We could say that, as long as we don’t imply that they are created by our activities.
So, waiting to be discovered by sentient beings with appropriate faculties. To check my understanding, to put humour on the list, we’d need to decide whether it transcended our own specific psychology (ie could in principle be enjoyed and “played with” by an alien sentient being with appropriate facilities, like we imagine mathematics or music could be); and, of course, not be reducible to those already in your taxonomy.
The main thing is that it not be explicable in terms of something else. Suits definition of games is in psychological terms plus some. Humor is a harder case, but I doubt it could stand by the other categories for irreducibility.
Would Bernard Suits’ Grasshopper put games on his list?
Can we say that three later kinds are evaluative kinds of beings ? logical , moral and aesthetical values ; in contrast with non evaluative beings : material , mental , and abstract beings
Yes, we can–they are normative (but in three different ways).