Philosophers often think quite highly of what they are doing, and those engaged in metaphysics are no exception. Indeed, metaphysicians offer perhaps the clearest example of this attitude, for they frequently insist that their work is not only important but, in fact, necessary. After all, who could deny the self-evident truth that everyone has ontological commitments in the sense that everyone takes something to exist. All of us – or practically all of us – believe that there are chairs, people, money, atoms, and so on. This, it is claimed, already suffices to make metaphysics inevitable.
Now, of course it is obvious that the scientist and the layperson both make ontological commitments in this very general way. But from that alone one cannot directly infer that theories of tropes, grounding, essences, composition relations, gunk, real definitions, and the like are by the same token indispensable. Since it is equally obvious that most of us don’t in our everyday lives or even within academia take any part in speculating about such things.
In order to make this clearer, let’s distinguish two types of ontology: first-order ontology and second-order ontology.
First-order ontology consists of scientific and everyday ontology, that is, of those ontological commitments that are made in the natural and human sciences, and in our mundane life. In science, first-order ontology simply consists of the scientific theories.
Naturally it goes without saying that the scientific and manifest image of the world can be very different, to use Sellarsian terms. Come to think of it, they’re frequently incompatible with one another. Our everyday beliefs don’t many a time correspond with what science tells us about the world. But, then again, many scientific theories aren’t fully compatible either (think of quantum mechanics and general relativity) and the same goes with ordinary worldviews (think of theism and atheism). Thus, first-order ontology should be considered as an umbrella term which does not refer to some kind of a unified whole.
Second-order ontology, on the other hand, could also be called metaphysical ontology. It encompasses the sort of stuff that metaphysicians do when they philosophise. Second-order ontology is likewise a blanket term. Anyone who has read an introductory textbook on metaphysics knows that the theories of second-order ontology often contradict and compete with each other.
As a side note, this division of the two kinds of ontology is not without predecessors. Similar ideas can be found, for instance, in the works of James Woodward, Paul Humphreys, and Penelope Maddy.
So, the worry here is that metaphysicians are endorsing a motte-and-bailey tactic when they declare the necessity of their discipline. A motte-and-bailey is an argumentative strategy based on equivocation. It is employed when a proponent of some position conflates her doctrine, which is difficult to uphold, with another one that is considerably easier to defend, such as a trivial truth. In our case, the metaphysician claims that doing second-order ontology is unavoidable by pointing out that first-order metaphysics is inescapable. Thus, she equivocates first- and second-order ontology simply because the terms “ontology” and “metaphysics” can be applied to both of them, even though it is clear that they are two very different things.
But maybe I’m being a bit uncharitable here. Occasionally, there is clear evidence that metaphysicians do respect the differences between the two ontologies. And instead of conflating them, the philosophers maintain that first-order ontology already contains hidden second-order assumptions. Alternatively, the metaphysician might argue that first-order ontology requires second-order ontology to back it up, even if it wasn’t concealed in first-order ontology from the very beginning.
Such claims, however, are considerably more difficult to sustain. Remember that ordinary folk, scientists, and other members of academia usually don’t bother themselves with second-order ontology. Moreover, the question arises: which second-order theory, or which set of second-order theories, is included in or required by our first-order ontology? There are a number of metaphysical creeds, after all. Many of them are inconsistent with each other and most of them consistent with our first-order ontology. (And if a theory of second-order ontology conflicts with first-order commitments, then evidently the first-order ontology didn’t contain it or require it.)
Now, usually the same first-order commitment is compatible with several mutually incompatible second-order theories. Therefore, all of the theories are clearly not contained in our first-order ontology. And yet, there seems to be agreement on how first-order commitments should be made. In order to convince someone of the existence of chairs, you can simply show her a few of them. In a similar fashion, physicists and chemists can agree on what basis we should accept the atomic theory. The same is true about sociologists and anthropologists when they state that a medium of exchange, in other words money, is used within a community. Sometimes, of course, determining such things is not easy. But even in those situations, second-order ontology seems to be of little help.
Our first-order commitments are based on some, more or less, shared standards. These criteria aren’t apparently used to make second-order commitments, since there is no agreement about what those commitments should be. In addition, second-order ontology doesn’t seem to lay down the standards of choice, because there is agreement of the criteria but not of second-order ontology. Moreover, we know that all second-order theories cannot be right, as they are irreconcilable. And at the same time, we don’t know which, if any, of them are correct. Hence, it is rather easy to see that one can do first-order ontology without second-order ontology.
To be fair, I must admit that it is important to find out how our first-order commitments are made. In what way do we justify them? What are they based on? Why do we end up accepting the existence of something instead of something else? But to answer these questions it is perhaps more sensible to consult the epistemologist, the philosopher of science, or better still, the sociologist and the psychologist. And yes, we can still call the study of such topics “ontology”.
However, scientists on their own appear to be doing a pretty decent job in making their first-order commitments. Like Arthur Fine has stated, science doesn’t need “to rely on metaphysical or epistemological hearing aids” (Fine 1984: 63). In this sense, the physicist is the best metaphysicist, and here the term “physicist” should be taken as a synecdoche of all practitioners of human and natural sciences. If the metaphysician disagrees and insists on the use of hearing aids, the burden of proof lies on her shoulders.
Fine, Arthur (1984): “And Not Anti-Realism Either” Noûs, Vol. 18, No. 1, pp. 51–65.
Humphreys, Paul (2013): “Scientific Ontology and Speculative Ontology” in Scientific Metaphysics, Don Ross, James Ladyman, and Harold Kincaid (eds.), Oxford: Oxford University Press, pp. 51–78.
Maddy, Penelope (2007): Second Philosophy: A Naturalistic Method, Oxford: Oxford University Press.
Sellars, Wilfrid (1991): “Philosophy and the Scientific Image of Man” in Science, Perception and Reality, 1963, Atascadero: Ridgeview Publishing Company, pp. 1–40.
Shackel, Nicholas (2005): “The Vacuity of Postmodernist Methodology” Metaphilosophy, Vol. 36, No. 3, pp. 295–320.
Woodward, James (2015): “Methodology, Ontology, and Interventionism” Synthese 192, 3577–3599.