Philosophical Studies

, Volume 141, Issue 3, pp 281–297

Emergent substance


    • Department of PhilosophyWake Forest University

DOI: 10.1007/s11098-007-9160-6

Cite this article as:
Toner, P. Philos Stud (2008) 141: 281. doi:10.1007/s11098-007-9160-6


In this paper, I develop an ontological position according to which substances such as you and I have no substantial parts. The claim is not that we are immaterial souls. Nor is the claim that we are “human atoms” co-located with human organisms. It is, rather, that we are macrophysical objects that are, in the relevant sense, simple. I contend that despite initial appearances, this claim is not obviously false, and I defend it by showing how much work it can do.

Once upon a time, there was a dispute between St. Thomas Aquinas and certain Franciscan philosophers over whether there can be a plurality of substantial forms in one substance. The Franciscans answered in the affirmative, while St. Thomas answered in the negative. St. Thomas held that accepting multiple substantial forms leads to tremendous philosophical difficulties—difficulties which are avoided entirely by holding that there is but one substantial form per substance.1 Well, on the current ontological scene, there are some tremendous philosophical difficulties: I shall argue here that by adopting St. Thomas’s view of substance, or something like it, we can entirely avoid these difficulties.

The view I present here involves some substantive metaphysical commitments. Some philosophers—those who are strongly inclined to accept the doctrine of microphysical supervenience, for example2—may find my position too much at odds with their basic metaphysical views to consider it as a serious option. Those who are already inclined, however, toward a more Aristotelian or Lockean essentialism may find the view more attractive. At any rate, what I show here is that my theory of substance solves lots of problems, and does so without pushing us to accept any obviously false or counterintuitive claims.

The paper has four parts. In Sect. I, I give an initial motivation for my view by showing how one who accepts my view can answer two important metaphysical arguments that push in opposite directions. In Sect. II, I present the view in detail. In Sect. III, I show some more of what the view can do, and in Sect. IV, I reply to objections. There is a danger to dividing the paper up in this way, because the break between sections one and three may make it more difficult to assess the costs and benefits of the view. However, the view I describe in Sect. II is somewhat surprising, and I think it will be helpful for readers to have a sense of why someone might believe it before they invest their effort in reading in detail about the view itself.

1 I

The Vagueness Argument (VA) purports to show that composition is unrestricted—that any two objects compose a third. That is, if composition is unrestricted, then there are objects like dog-and-tree sums, where a dog-and-tree sum is an object composed of this dog and this tree. There is nothing special about dogs and trees, of course. The view is that any two objects compose a third. (And, for that matter, the view is not restricted to pairs: on this view, any three objects compose a fourth, and so on.) One needn’t accept unrestricted composition, of course. One might accept nihilism, which claims there are no composite objects. Or one could accept some form of restricted composition. A believer in restricted composition might think that the parts of my watch compose an object (the watch), but my watch and my left sock do not compose an object.

Again, the point of the VA is to force us to accept unrestricted composition—a position many people find difficult to believe. The argument proceeds roughly as follows. If composition were restricted, the restriction would have to be vague. But if the restriction is vague, then it’s sometimes vague whether composition occurs, and that’s impossible. Therefore, composition is unrestricted.3 To flesh out the idea here, assume that we have a supervenience base for composition, and that this supervenience base comes in a continuum. For comparison, imagine that baldness supervenes upon a base consisting of the number, thickness, and distribution of hairs on a head. That supervenience base comes in a continuum: it can be altered one hair at a time. Since there are no sharp cut offs in such a continuum, it is implausible to suppose that a person at one step along the continuum is determinately bald, and a person at the very next step along the continuum is determinately non-bald. So, if composition is restricted, and if composition supervenes upon a continuum with no sharp cut offs, then it looks as though it is sometimes vague whether composition occurs, just as it looks as though it is sometimes vague whether a person is bald. But whether composition occurs cannot be vague, so composition must be unrestricted.

As I said, many people find unrestricted composition difficult to believe. Fortunately, premise one of the VA seems questionable at best. It is not a difficult matter to show that there can be non-arbitrary, yet sharp, cut offs on the composition continuum. In my opinion, there is a sharp cut off at the point at which an entity emerges—“over and above the parts,” as some might say—which has non-redundant (or irreducible) causal powers.4 So one can, without any vagueness, restrict composition. This response to the argument gives us an ontology that includes the little things that make up the putative composition continuum—things which I shall call ‘atoms’—and macrophysical objects with non-redundant causal powers. (‘Atoms’ serves here as a placeholder for whatever the lowest level objects or processes might be, if, indeed, there are any. My theory of substance is consistent with gunk, or with process philosophy, or with the view that there are simples.)

This ontology, however, leads to our second problem: the Overdetermination Argument (OA) for eliminativism.5 The OA attempts to show that some (alleged) macrophysical objects—humble things like chairs, tables or baseballs—do not exist. It is pushing us, then, in just the opposite direction as the VA. The latter tries to make us believe in too many things. The former tries to make us believe in too few: it wants us to eliminate them from our ontology. I will address the OA in a moment: first, some scene-setting.

In what follows, assume for the sake of discussion that there are emergent objects of the sort that provide a sharp cut off in the composition continuum. And then assume that when some atoms come to compose a new, emergent, object, the atoms remain present. To put this in classical terminology, I am asking you to assume that the atoms do not undergo a substantial change when they become the supervenience base for an emergent object.6 They remain precisely as they were before they came to compose this emergent object. Call this latter assumption ‘atomism.’

Of course, ‘atomism’ is a term used in a variety of ways. So do bear in mind that all I mean by for present purposes is what I say above—that there are atoms that remain essentially unchanged by becoming parts of composite objects. Imagine that an oxygen atom is an atom in the sense in which I’m using that term here. (Obviously, it isn’t. But we’re pretending.) Imagine, further, that a water molecule is an emergent object in the sense discussed above. The belief that oxygen atoms remain oxygen atoms—and that they remain the same oxygen atoms—when they become parts of water molecules is atomistic in my sense.

Now, we come to the OA. Imagine that some kids have just hit a baseball through a picture window. What causes the shattering of the window? The obvious answer—obvious, that is, provided one endorses some form of substance causation—is that the baseball caused it. Many people find substance causation worrisome, and prefer event causation. But notice that it is quite consistent with event causation to say that the baseball is causally involved in the shattering. The relevant event is, presumably, the baseball’s going through the window. This is really all the proponent of the OA needs to get the argument going: a recognition that the baseball is importantly involved in the shattering. The details of one’s theory of causation don’t seem to matter much here.

However, many people endorse a bottom-up metaphysics, according to which the entities that physics quantifies over provide complete causal explanations of all phenomena. According to such a metaphysics, the obvious answer will not do, since physics does not quantify over baseballs. To the bottom-up metaphysician, the proper answer seems to be that, working in concert, the atoms that compose the baseball shatter the window. That leaves the baseball out of the causal loop, and leaves us with a different question: what, exactly, is the role of the baseball? What does it cause? There seem to be three options. First, it causes nothing. Second, it overdetermines the effects that are also caused by its parts. Third, it doesn’t exist at all. To endorse option one is to epiphenomenalize macrophysical objects. That’s bad. To endorse option two is to endorse systematic causal overdetermination. That’s bad. Trenton Merricks endorses the third option in the case of (alleged) objects like baseballs. To me, this seems worst of all. But regardless of whether one is prepared to join Merricks in eliminating inanimate macrophysical objects, it does seem desirable to join him in not eliminating certain other macrophysical objects, such as human beings. As we just saw, Merricks believes in composite objects which have non-redundant causal powers, and he believes human beings have non-redundant causal powers: that is, he believes in humans. So he cannot escape the OA where humans are concerned in the way he escapes it where baseballs are concerned.

So, if some kids throw a philosopher through a window, what causes the shattering of the window? There still seem to be three possibilities. First, the atoms and not the philosopher. Second, both the philosopher and the atoms. Third, the philosopher and not the atoms. Option one, as above, epiphenomenalizes the philosopher. Option two, as above, involves systematic causal overdetermination.7 That leaves option three: but this option seems hard to defend. After all, it seems like, suitably grouped together, the same atoms would cause a shattering if they weren’t composing a philosopher. So what makes them causally inert when they do compose a philosopher?

One way (perhaps the only way?) to make sense of option three is to reject atomism, and hold that—in a sense to be carefully explained below—the atoms are no longer present when “they” compose a philosopher. And this, in fact, is my response to the OA. But it isn’t merely a reply to the OA. Go back to the composition continuum, and assume that atomism is false. Assume, that is, that when atoms come to compose an object, they undergo a substantial change. Imagine that once composition occurs, the only object that remains is the emergent substance: nothing remains “down there” at the microphysical level (with any causal powers of its own). This move gives us a straightforward, non-vague cut-off on the composition continuum, one that complements the original one that we considered. So by denying atomism (in the way in which I deny it), we get easy solutions to our first two problems.

However, if the rejection of atomism is unbelievable, then my proposal, for all that, is a non-starter. So in the next section, I will briefly explain how the view works, and why it’s not as bad as it might seem.

2 II

Before I explain the view, I should make something else clear. I will use various examples of emergent substances throughout the paper. Nothing turns on whether you believe that any of the examples plausibly count as emergent substances. I myself am not entirely sure about most of them, and simply select them for heuristic purposes. Human beings are the only case which I take to be non-negotiable: in my opinion, we are paradigm cases of emergent substances. However, I will not argue here that human beings are emergent substances. I will simply assume it. The central reason I would offer for thinking we are emergent substances is that we have irreducible causal powers, such as libertarian free will, which (to me) seems unexplainable in a purely reductionistic way. But it’s not necessary to buy into that assumption to follow along with the argument of this paper. My argument is that the notion of emergent substance is a coherent and useful one. Now we turn to that notion.

In what follows, the term ‘substance’ will play a vital role. When I speak of a substance, I mean an object with non-redundant (i.e., irreducible) causal powers. This use of the term is somewhat idiosyncratic.8 Nevertheless, it certainly picks out something that has long been held to be at least a mark of substance—namely, activity. As St. Thomas says, “As passive power, or passivity, follows upon being in potentiality, so active power follows upon being in actuality; for everything acts by being in actuality, and is acted upon by being in potentiality.”9 So it seems fair to take the possession of non-redundant causal powers as having been long held to be at least a necessary condition of substancehood. (For present purposes, I shall treat it as though it were both necessary and sufficient, though I am not sure whether it is.)

I do not consider desks or chairs or baseballs to be substances, because I believe none of these objects has non-redundant causal powers. That is, I believe everything these things do is fully explainable in a bottom-up way.10 The atoms, when they are parts of objects like these, do not undergo substantial change. Things are different with emergent substances, however. While atomism seems true in the case of non-substantial macrophysical objects, I will argue that it is false in the case of emergent substances. When atoms compose a substance, they lose their causal powers. The causal powers of a substance—all of them—reside in the substance as a whole, and not in its parts.

Let me put this view another way. Atomism holds, in effect, that parthood is always an external relation. So, just as being in North Carolina is an external relation for me—when I leave North Carolina, I am not essentially changed—being a part of a substance is an external relation for my atomic parts.11 Anti-atomism holds, on the other hand, that parthood is (at least sometimes) an internal relation. (So here again, we must be careful with the terminology. ‘Anti-atomism,’ as I use it, does not imply that matter is infinitely divisible.)

I’ll need to say a few words here about the distinction between internal and external relations. The distinction has a rather checkered philosophical history, and it might be thought that by invoking it, I am only muddying the waters. After all, Ewing identified ten distinct notions of internal relations that could be found in the works of various idealists.12 Well, it’s certainly true that the term has been used in many ways, but I’ll try to stick to one, and in so doing avoid, I hope, muddying the waters.13 Consider the property of standing in the internal relation ‘being a part of X.’ (This relational property is not the relation itself; but having the property is a necessary correlate of standing in the relation.) Call this property Φ. On my account of internal relations, “supposing A has Φ, then anything which had not had Φ would necessarily have been different from A.”14 In short, internal relations are simply the correlates of the essential relational properties of an object.15

So, again, anti-atomism denies that parthood is always an external relation: there are some cases where having the property of being a part is essential to the thing has that property. But anti-atomism comes in two strengths. (Imagine, in what follows, that carbon atoms are philosophical atoms.) According to weak anti-atomism, when, say, a carbon atom becomes part of a substance, it is essentially changed in such a way that the carbon atom that’s part of the substance is not the same carbon atom that existed before becoming a part of the substance: a substantial change has taken place. On this view, there are two carbon atoms: the old one, which was not a part of a substance, and the new one, that is a part of a substance. However, on this view, the new carbon atom is still a substance in its own right. It has causal powers of its own. It’s a different substance than the initial atom, but it’s still a substance. This is a venerable view. Plato, for example, apparently accepted weak anti-atomism.16 Nevertheless, this is not the version of anti-atomism I endorse. Whatever its attractions, it cannot solve all the problems I claim my view can solve.

Instead, I endorse strong anti-atomism, according to which no substance has a substance as a proper part. (Obviously, substances have themselves as improper parts.) Whenever an atom becomes part of a substance, it is not merely changed into another atom, it actually ceases to be a substance at all.

To get a clearer picture of my view, consider the substratum theory. (I do not accept the substratum theory, I simply use it as a heuristic.) Imagine that a substance has a substratum in which its properties inhere. Imagine further that hydrogen atoms and oxygen atoms are substances, and also that they are atoms in my sense. Each atom has a substratum in which the various properties—including, of course, the causal powers—of that atom inhere. Now, imagine two hydrogen atoms and an oxygen atom coming together to form a water molecule; and suppose that the water molecule is also a substance. When the water molecule comes into existence, the original three substrata disappear, and a single new substratum comes into existence. The properties that used to inhere in the three atomic substrata now inhere in that one, molecular, substratum; now, there is just one substance present—the water molecule.

Certainly, this is just one way to imagine the emergence of the new molecular substance. The atomist—if she believed in emergence, which she might—would imagine that the three atomic substrata remain present, and a new molecular substratum emerges. The weak anti-atomist would imagine that the initial three atomic substrata are destroyed, and then three new atomic substrata, together with a molecular substratum, come into existence.17

It is, I take it, undeniable that the atomic parts of a water molecule do share many properties with oxygen and hydrogen atoms that are not parts of any molecules. There are many qualitative similarities between the parts of the molecule and the original atoms that, according to my view, lost their identities in giving rise to the molecule. This qualitative similarity may be thought to undermine my view, but in fact it does not. Rather, the similarity amounts to what I shall call the “nominal presence” of atoms in a substance.

Before I can explain nominal presence, I shall have to say a few words about the parts of substances. I have denied that substances have substances as parts. But that doesn’t mean they have no parts. Lowe suggests that “something is to be counted a ‘part’ of a substance in this sense only if that thing is itself a substance. We may call such a part a ‘substantial part’.” On the other hand, a spatial part is simply a geometrically defined section of the substance. For example, he says, “the left-hand third of my desk as it faces me is a spatial part of it.”18 I accept this distinction, and I hold that although substances lack substantial parts, they do have spatial parts. And these spatial parts exemplify many properties. (The ultimate owner of these properties is, of course, the substance itself and not that spatial part.)

To use another rather crude example to illustrate my view, pretend a scientific atom such as a carbon atom is a cluster of little balls with one or more other balls orbiting (the way the old models of atoms looked). Let us continue to pretend that these scientific atoms are also atoms in my sense. Imagine two such atoms joining up to form a molecule: this would leave us with two clusters of balls, and two paths of orbiting electrons. When we think in terms of this model, it seems obvious that the original two atoms are still there, and thus it seems obvious that the molecule has substantial parts. But this is confused. Certainly, the molecule has spatial parts, and those spatial parts have many qualitative properties in common with the original atoms that correspond with those spatial parts. (The balls in the nuclei started out as round and red, perhaps, and round and red are still being exemplified in those areas.) However, the important question is not whether the spatial parts bear a resemblance to the substances that existed prior to composition: they usually will. The important question, rather, is what owns the properties. I say, again, that it is the molecule that owns them, not the parts.

With this notion of spatial parthood in hand, we can move to the notion of nominal presence. A notion of nominal presence similar to mine is already found in the literature. Michael Rea writes “(A)n object satisfies a sortal in the classificatory way just in case that sortal gives the metaphysically best answer to the ‘What is it?’ question for that object, and an object satisfies a sortal in the nominative way just in case the object exemplifies the distinctive qualitative features of those things that satisfy the sortal in the classificatory way.”19 And an object that satisfies a sortal in (merely) the nominative way is, on my view, nominally present.

Now, as we saw, I grant that the spatial parts of the molecule exemplify (most of?) the qualitative features of the original atoms. But I deny that “it is an atom” gives the best answer to the “what is it?” question when asked of atoms that are parts of molecules. So I say the atom is merely nominally present in the molecule. My main reason for denying that “it is an atom” gives the best answer to the “what is it question” when asked of atoms that are parts of molecules is that I say the causal powers that once belonged to nominal atoms belong to it no longer: they now belong to the molecules of which the nominal atoms are spatial parts.20

Thus, the qualitative features of the spatial parts explain the similarities between the nominal atoms and genuine atoms. Imagine that a sodium atom that is part of a sodium chloride molecule is not a substance. (Imagine, that is, that sodium chloride molecules are substances.) That sodium atom is still nominally a sodium atom. That is, we still call it a sodium atom, and with good reason. In this extended—and far more natural sense—substances do have atoms as parts. But these atoms are not identical with the substantial atoms that existed prior to becoming parts. They could not be: the atoms that were present prior to the emergence of the molecule have undergone substantial change.21

Do these nominal atoms exist? Yes. On my view, to say that “x’s exist” is to say that “the property x is instantiated.”22 It seems quite clear that the property of being a sodium atom is instantiated by certain spatial parts of a sodium chloride molecule. If it weren’t, then it wouldn’t make any sense to speak of nominal sodium atoms. We call them sodium atoms because for all the world, they appear to be sodium atoms. To my mind, that’s sufficient for saying that the property of being a sodium atom is instantiated: the atoms exist. Indeed, I would say that it is part of what it is to be a sodium atom that under certain conditions, things that count as sodium atoms are substances, and under other conditions, things that count as sodium atoms—nominal sodium atoms—are not substances. (Again, this is merely meant as an example: nothing turns on whether sodium atoms can really be substances in my sense.) This would not be true of all substances. For example, human beings cannot ever become merely nominally human beings, except perhaps in the strained sense of becoming corpses. We are not liable to become nominal human beings that are parts of a larger substance.

Now that the view is on the table, let’s return to the work it can do.


The Problem of Material Constitution, in its various permutations, looms large in contemporary metaphysics.23 Rea has argued that the Problem is generated by the incompatibility of five plausible assumptions about material objects. These assumptions are:

(i) there is an F and there are ps that compose it, (ii) if the ps compose an F, then they compose an object that is essentially such that it bears a certain relation R to its parts, (iii) if the ps compose an F, then they compose an object that can exist and not bear R to its parts, (iv) if the ps compose both a and b, then a is identical with b, and (v) if a is identical with b then a is necessarily identical with b. Let us call these assumptions, respectively, the Existence Assumption, the Essentialist Assumption, ... the Principle of Alternative Compositional Possibilities (or PACP for short), the Identity Assumption, and the Necessity Assumption.24

To solve the Problem, one has to reject at least one of these assumptions: and because each is plausible, it is costly to reject any. Consider one instance of the PMC—the Growing Argument. Imagine that at t1, Patrick borrows some money from Benjamin. Then, at t2, Benjamin returns to collect on the debt. Patrick, however, is unwilling to pay. He notes that at t1, he was a certain aggregate of particles. But now, at t2, some new particles have been added to the aggregate. Therefore, there is a different aggregate at t2 than there was at t1. And, consequently, “Patrick” is, in fact, a different person at t2 than “he” was at t1. And, thus, he does not owe Benjamin any money. The Growing Argument, then, purports to show that growth is impossible: adding any particles to any aggregate results in a new aggregate. But, of course, the same would be true if we removed some particles from the original aggregate. Indeed, the Growing Argument, despite its name, would, if successful, show that physical objects cannot undergo any change of parts at all.

This argument clearly makes four of five of Rea’s assumptions. Its rejection of the fifth—PACP—just is the point of the argument, which is designed to show that PACP is incompatible with the other assumptions. More specifically, the argument makes the Existence Assumption by assuming that there are such things as Patrick and the aggregate of particles. It makes the Essentialist Assumption in claiming that the aggregate cannot change parts without ceasing to exist. It makes the Identity Assumption in claiming that Patrick is identical with the aggregate. And it makes the Necessity Assumption in its rejection of the possibility that at t1, Patrick is identical with aggregate A1, while at t2, Patrick is identical with (different) aggregate A2.

Rea’s own solution to this problem allows him to endorse without qualification the Existence Assumption (Patrick exists, and the aggregate exists), the Identity Assumption (Patrick is identical with the aggregate) and the Necessity Assumption (Patrick is necessarily identical with the aggregate). Remember that I have adopted the notion of nominal versus classificatory presence from Rea: he uses the distinction to ground his solution. He argues that because Patrick is classificatorily a human being, and only nominally an aggregate, Patrick has essentially only those properties associated with the kind human being, and not those properties associated with aggregate. If that’s right, then we can reject the Essentialist Assumption with respect to Patrick, for it is not plausible at all that human beings necessarily have the same parts at all times at which they exist. In other words, if Rea is right, then it is only the false belief that the Identity Assumption entails that the human being has all the essential properties associated with aggregatehood that makes the Essentialist Assumption at all appealing in this case. Once we see that Patrick is an aggregate only nominally, then we’ll be happy to endorse the PACP and reject the Essentialist Assumption. Problem solved. Further, the distinction between classificatory and nominal kind membership allows Rea to solve every version of the PMC in the same way. He can reject the conjunction of the PACP and the Essentialist Assumption in every case.25

My theory of substance allows me to solve the PMC in essentially the same way. Substances have no substantial parts (at any level of decomposition). But an aggregate, on my view, does have substances for parts (at some level of decomposition). So nothing that is a substance in a classificatory sense could possibly be (identical with) anything that is an aggregate in a classificatory sense. Therefore, if I am a substance, I am not identical with anything that is classificatorily an aggregate. I might be, however, identical with something that is “nominally” an aggregate. An aggregate is made of substances (it is an essential property of any aggregate that it is made out of substances). But the aggregate I am identical with is not made of any substances. So that aggregate can’t be classificatorily a substance. But since it is qualitatively similar enough to an aggregate, it is nominally an aggregate: it lacks some of the essential properties of aggregates, however, including its inability to gain or lose any parts. Thus, as I said, I am able to solve the PMC like Rea does. So the PMC is not a problem.26

However, it makes sense to ask why one should prefer my view to Rea’s, if I solve the problem in the same way that Rea does. The simplest answer is that my view can do much more work than Rea’s. His answer to the PMC does not also serve as a way to navigate between the OA and VA, as mine does. Nor does it allow him to handle the problems I turn to next. So although my solution to the PMC is structurally identical with Rea’s, my view can do much more than his.

Turn next to the “Problem of the Many.” Assume my theory of substance is false, and that here in my chair an enormous number of atoms is swarming around. Many are obviously within my boundaries. Some, however, are not so obviously within my boundaries: or, rather, we might say that there are many equally plausible ways to draw my boundary lines. But if that’s right, then there are lots of aggregates of atoms that have a claim to be a human animal. So do we have lots of human animals sitting here? Or, perhaps, do we have no human animals, since the competition between the various aggregates forces us to rule that none counts?27

This Problem obviously assumes that parthood is merely an external relation for the atoms. But, of course, I say that it is an internal relation. Those candidate atoms swarming around my chair that are substances are not my parts, while those that are merely nominal atoms are my parts. There will be nothing vague about this, even if it isn’t something we can empirically discover: the Problem of the Many has no purchase here. Since there are philosophers so impressed by the Problem of the Many that they are inclined to deny that we exist at all, having a straightforward answer to this problem is philosophically very important.

Next, consider the “Unity of Consciousness” argument for dualism, which attempts to show that thought cannot be explained as the activity of an aggregate:

Every composite substance is an aggregate of several substances, and the action of a composite, or whatever inheres in it as thus composite, is an aggregate of several actions or accidents, distributed among the plurality of the substances... (S)uppose it be the composite that thinks: then every part of it would be a part of the thought, and only all of them taken together would be the whole thought. But this cannot consistently be maintained. For representations (for instance, the single words of a verse), distributed among different beings, never make up a whole thought (a verse), and it is therefore impossible that a thought should inhere in what is essentially composite. It is therefore possible only in a single substance, which, not being an aggregate of many, is absolutely simple.28

Look again at this line: “Every composite substance is an aggregate of several substances.” If one denies this claim, then the unity of consciousness argument cannot get started. If material substances are simple in the sense in which I claim, then there is no problem here.

Next, we consider the Problem of Individuation: if properties are universal, and if everything is ultimately reducible to properties, how can there be individuals? Michael Loux accounts for individuation by invoking the “substance kind.” “Kinds are universals whose instantiations are numerically different; but the instantiations of a substance kind just are the various substances which belong to or fall under it.”29 These substance kinds are not reducible to other universals—they are, in effect, nonstructural universals. He claims, further, that substances just are instances of substance kinds. Thus, he has an elegant solution to the Problem, and he avoids the difficulties that attend both the bundle theory and the substratum theory. My view—which, like Loux’s, is unabashedly Aristotelian—can be combined without any difficulty with Loux’s claims about substances being instances of individuating universals, and can thus handle the Problem of Individuation.

Thus, by rejecting (in effect) the plurality of substantial forms in a substance, we easily avoid a number of otherwise serious problems.

4 IV

Here I consider three objections. The most straightforward and obvious objection to my view is that it is just obviously, empirically, false. It might be thought that if my view is true, the bottom-up approach to substances would have to fail. After all, we explain a great deal about the activities of human beings—who I hold to be emergent substances—on the basis of the operations of their parts. If the parts don’t really have causal powers of their own, then it is difficult to see how we could get such explanations. But the bottom-up approach doesn’t fail, so my view must be false.

However, my view doesn’t undermine taking a modified bottom-up approach to substances. Very briefly, I would say that I have certain properties (being handed, or being [nominally] carbon atomed) in virtue of which I cause things. This is no different from an iron causing a burn in virtue of being hot. The iron doesn’t compete with the heat to be the cause of the burn. Similarly, I cause certain things by being handed, and certain other things by being carbon atomed. In other words, those properties do enter into causal explanations.

Here, my view is somewhat similar to the view of those who reject the Doctrine of Arbitrary Undetached Parts.30 Such people might say that I have no hands (or any other such parts, like a head or legs). I can certainly talk about my hands. I can hold them up and see them, or fall down and scrape them. But none of this implies I have hands.31 It means I seem to. And a good way to make sense of that is to say I am handed. Similarly, some of my spatial parts resemble, for instance, carbon atoms. Indeed, those spatial parts are nominal carbon atoms. In virtue of being carbon-atomed, I can do things. One who claims I have no hands will have to say something similar: I have no hands, but I can type in virtue of being handed.

The only conflict between my view and the bottom-up approach arises when the scientist insists upon making the metaphysical claim that the causal powers she sees at work at the lower levels actually belong to the lower level (nominal) entities. It is true that I cannot accept a claim that bottom-uppers would typically wish to endorse: that the objects at the fundamental level do all the causal work. However, I do say that we can give perfectly sensible causal explanations using the nominal objects at the fundamental level: I also say that although the real causal work is being done by macro-level entities, it is being done in some cases in virtue of their having properties at the micro-level. A bottom-up account that attributes the causal powers to my parts rather than to me isn’t the best one (because it makes an error about what entities are actually causally involved), but for practical purposes, it’s entirely adequate and, indeed, extremely helpful.

Consider what I take to be the same objection in a slightly different form. In this form, the objection is the challenge: “What about the water in organisms? Are we supposed to believe there’s no water in organisms?” Even philosophers who are generally friendly to a Thomistic metaphysic make this kind of objection. For example, Terence Nichols writes seems hard to deny that water is present as water in the blood and in the cells. It has not undergone a substantial change and become something else; even in solution it still functions as water. The presence of solutes and suspended solids does not change the water substantially but only accidentally, for example, by changing the spatial relations of water molecules with each other, the viscosity, or the boiling point (any solute dissolved in water will change the boiling point). Indeed, if the water in the blood or cells were not water as such, it could not function as a solvent for salts. Yet if it is water, it seems that there is more than one substantial form in the body.32

We need only to read the objection carefully to see that it isn’t really threatening. For example, notice that Nichols writes, “if the water in the blood or cells were not water as such, it could not function as a solvent for salts.” Why should we think this? Again, apparent conflict between my view and the bottom-up approach arises when people make the metaphysical—not scientific—claim that the properties involved in causal interactions inhere in the lower-level (nominal) substances rather than in the higher-level substance. That’s precisely the mistake that Nichols makes, by insisting that it has to be the water that’s doing the work. Isn’t it sufficient that the relevant properties—properties generally associated with waterhood—are present, although they now inhere directly in the organism rather than in the water? It seems so, since the properties are what are involved in the causal transactions. But that these properties are present is part of what it is for water to be nominally present. So any organism that has water nominally present will be able to do (most of) the kinds of things that water generally does, such as serving as a solvent for salts: it is no objection at all to my view that nominally present substances can continue to appear to do many of the kinds of things they do when they’re not part of an organism. That claim is built right into my view. Further, Nichols’s contention that the water has changed only accidentally, rather than substantially, simply begs the question against my view. For these reasons, I do not find his objection troubling.

A second objection is that my view makes laws of nature terribly messy. This objection would have it that I complicate matters intolerably by requiring there to be laws of nature such as that “under such and such conditions, some atoms pop out of existence, and a new entity pops into existence.”

First, if there is a problem here for my view, there is a problem for any believer in restricted composition, all of whom will—if the objection is cogent—have to accept laws of nature of the form “under such and such conditions, a new entity pops into existence.” So it’s not clear that we have an objection specifically against my view here. Second, however, I don’t think the objection is a good one anyway. The situation it describes would be messy, but I don’t see how it is entailed by my view. If laws of nature are thought to be relations between properties, for example, then as I’ve pointed out repeatedly, I still have the relevant properties involved in the relevant causal transactions. As far as I can see, it makes to difference in terms of cashing out the laws of nature whether the properties involved inhere in atoms or larger substances.

A third objection is that if the properties all inhere in the one substance, and not ultimately in its parts, then the one substance can exemplify contradictory properties. To get a sense for how this objection works, think of the old models of atoms again. We’ve got some balls orbiting around a cluster of other balls. Some of the balls are, let’s say, red, and others are white. So the atom exemplifies both white and red. This particular example is easy enough to answer, since it’s clear that there is no contradiction. The atom is white here, and red there. But there is a legitimate concern in the neighborhood.

Or is there? One might try to insist that the objection misses the point. For as the Philosopher wrote, “the most distinctive mark of substance appears to be that, while remaining numerically one and the same, it is capable of admitting contrary qualities.”33 This is not exactly an answer to the objection, though, since one wants to know why substances admit contrary qualities. As Aristotle points out, one has to take into account the circumstances. The substance admits contrary qualities, but in distinct ways. Now I’ve just pointed out one circumstance that explains how one and the same substance can be both white and red, and yet we fail to have a contradiction: the relevant circumstance is that it’s red here and white there. But perhaps there are non-spatial properties, where the distinction can’t be easily drawn. If the spin of a quark is taken to be non-spatial, one can’t say that I exemplify positive spin here and negative spin there. So it might seem that the circumstances don’t help in this case: I exemplify both positive spin and negative spin, and this is impossible. So my view is false.

That’s far too quick. First, one might have independent reasons for taking an anti-realist approach to that kind of talk.34 And if one is otherwise persuaded that my theory of substance is right, then that would provide additional motivation for becoming an anti-realist in this area. An anti-realist about quantum mechanics will have little reason to worry about this particular objection. So this is one way around the objection. But I don’t think it is the only way around it.

The kinds of properties that we’re concerned with are the kinds of properties that determine what the thing that has them does. The spin of a quark, in some complicated way, helps to determine what the quark does (it is a dispositional property). But it only helps. The rest of the story has to do with the rest of the circumstances. To say that a quark has negative spin is, I take it, to say that it is disposed to behave in certain ways, given certain circumstances. But if that’s right, saying that a substance (say me) exemplifies both negative spin and positive spin, in virtue of having nominally present quarks as parts, is simply to say that under one set of circumstances, I will behave in one way, and under a different set of circumstances, I will behave in another way. I don’t think I’m quite competent to specify exactly what these various sets of circumstances would look like, but that they are part of the story one way or the other seems clear. There is no contradiction to be found here.

In my estimation, the benefits of accepting my theory of substance far outweigh the cost.35


For an excellent discussion of the relevant parts of the Thomistic ontology, see Nys (1942, pp. 118–262, esp. 161–191 & 247–262). For more recent discussion, see Clarke (2001, chaps. 4, 6 and 9), Brown (2006, esp. chap. 6), Bobik (1998) and Connell (1988). For a related discussion, see Leclerc (1969). For a fine discussion of the Franciscan side of the debate, see Cross (1998, chap. 4).


This is, roughly speaking, the view that the properties of macrophysical objects are wholly determined by the properties and relations of their atomic parts.


This is a paraphrase of David Lewis. See Lewis (1988, p. 212).


This kind of reply to the argument is developed in detail in Merricks (2005).


For this argument, see Merricks (2001, chap. 3).


A substantial change occurs when one substance ceases to exist and a new substance or substances begins to exist, composed of the same matter that composed the original substance. When an organism dies, a substantial change takes place. The animal ceases to exist, and the matter that once composed it now composes a mass of decaying tissue.


Here I oversimplify for the sake of brevity. Merricks’s own view is a version of option two, and he rightly denies that his view commits him to overdetermination. Nevertheless, his solution implies that despite being macrophysical objects, human beings have no causally efficacious macrophysical properties. And, to me, this is puzzling at best.


‘Substance’ is commonly understood as something like “that which can exist by itself,” or “that in which properties inhere, but which itself inheres in nothing,” or other such “independence” criteria. For a thorough discussion of substance, see Hoffman and Rosenkrantz (1997). I think the authors give some fine reasons for rejecting standard independence criteria; however, I find their own alternative suggestion problematical in several ways. (Most obviously, they are eliminativists about artifacts.) Michael Gorman has been trying to resuscitate the independence criterion of substance, but he believes that while it is necessary, it is not sufficient. I am inclined to think that his account and my account might together constitute necessary and sufficient conditions for substancehood, but I’m not sure. See Gorman (2006).


Summa Contra Gentiles, II, 7. Fr. Norris Clarke has stressed the centrality of action in St. Thomas’s thought in a number of places; cf. “Action as the Self-Revelation of Being,” and “To Be is to Be Substance-in-Relation,” both repr. in Clark (1995).


For the ontological story I tell about aggregates such as chairs or baseballs, see Toner (2006). In note 7 above, I pointed out that Merricks defends a version of option two that nevertheless doesn’t entail overdetermination. I also defend, in effect, a version of option two that does not involve overdetermination. One might justifiably ask: if I can solve the OA with respect to baseballs without calling them emergent substances and saying very odd things about their parts, then why shouldn’t I say the same thing about us? Why accept emergent substance at all, if there’s another option available? Here, I can simply say that this paper as a whole answers that question: the emergent substance view allows me to solve many problems, while still believing that I have irreducible causal powers such as libertarian free will. I believe no such thing about baseballs, and so I feel quite justified in telling an entirely different story about them.


I specify that it’s an external relation for my atomic parts because one could endorse atomism with respect to atoms, and reject it for parts like hearts or hands: it’s easier to reject atomism in the case of the latter kinds of parts.


Ewing (1933, pp. 119–136).


The sense in which I use the term is (or is very much like) Ewing’s seventh sense, according to which the relation is internal if it “makes a difference to” its terms. Ewing cashes this out by saying “where two terms are related in some specific way ...they could not both have been what they are without the relation being present.” (ibid., p. 131.) The “both” is important, for Ewing recognizes—what others do not—that “in all cases of relations between concrete terms one of the terms could have been the same without the relation being present.” This is important for my purposes, since although I believe being a part of me is internal to all my parts, I do not believe that having those parts is, in all cases, internal to me.


Moore (1993). Of course, in this paper, Moore quite rightly criticizes an idealistic argument that purports to show that all relations are internal, drawing, in effect, the distinction between the necessity of the consequence and the necessity of the consequent. So while Moore famously rejects the idealist notion that all relations are internal, he does accept—as do I—that some relations are internal. This paper of Moore’s is also the basis for the distinction between the relation itself and the relational property that I draw above.


Here I understand essential properties in their standard modal sense: x has p essentially iff it is necessary that x has p if x exists. I am not sure, actually, whether this modal sense of essentiality is acceptable. For some reason for doubt, see Gorman (2005).


On this point, see Harte (2002). Other people who endorse similar claims are Earley (2005) (as I read him: but he could also be read as endorsing strong anti-atomism); and Nichols (1996).


For discussion of lots of ways to understand the emergence of substances, none of which is very much like my own way, see O’Connor and Jacobs (2003). The view I am arguing for involves a notion of emergence that is quite similar to Paul Humphreys’s account. Humphreys focuses on the emergence of properties rather than objects. But the story he tells about emergent properties is very much like the story I tell about the emergence of objects. That is, he claims the lower-level properties are “used up” in the “fusion” into emergent properties; and he uses this result to avoid the force of the exclusion argument. For his view, see Humphreys (1996) and (1997).


Lowe (1996, p. 36). I should stress here that Lowe understands substancehood quite differently than I do, so he will count different kinds of things as substantial parts than I do. It is part of Lowe’s more complete definition of spatial parts that they can’t be separated from the substance they’re part of and retain their identity. Or, in other words, for spatial parts, parthood is an internal relation. For similar accounts of the distinction between kinds of parts, see Molnar (2003, pp. 33–34) and Heil (2003, pp. 174–175).


Rea (2000, p. 172).


All of the properties of the atom now belong to the molecule, and not just its causal powers. But the causal powers are really the most important ones, given my notion of substance.


Here, I take for granted that substances are essentially substances: one and the same thing cannot be a substance at one time, and a non-substance at another time. The principal motivation for holding such a view is that an object cannot change from one ontological category to another. One and the same thing cannot be an abstract object at one time, and a concrete object later. Similarly, one and the same thing cannot be a substance at one time, and a mere spatial part of something at a later time.


On this, see Toner (2006).


For an excellent discussion of the various forms of the Problem, and a diagnosis of what the Problem consists in at heart, see Rea (1995).


Ibid., p. 527.


I base this account of Rea’s solution on Rea (2000, pp. 176–179).


Of course, the solution I have just outlined works only in the case of substances. If chairs are not substances—and I say they are not—then it doesn’t help with them. Fortunately, I have solutions for such objects as well. As noted above, I present them in Toner (2006).


I here paraphrase (while changing his example) David Lewis (1993, p. 164).


Kant (1965, p. 335 (A352)). Cited in Hasker (1999, p. 123). Kant doesn’t endorse this argument.


Loux (1978, p. 163). For more on Loux’s view, see his 1998.


The locus classicus here is van Inwagen (1981).


Cf. Olson (1995).


Nichols (1996, p. 313).


Aristotle, Categories, Chap. 5 (4a 10ff), trans. E. M. Edgehill, McKeon, ed. (1941). He meant that substances admit contrary properties at different times, but the principle here is the same.


On this point, see, for example, French (2006). French points out that “Quantum mechanics is compatible with two distinct metaphysical ‘packages,’ one in which the particles are regarded as individuals, and one in which they are not. Thus we have a form of underdetermination of the metaphysics by the physics.” As he says, this provides grist for the anti-realist’s mill. It is also worth noting that one might lean towards anti-realism with regard to quantum mechanics without endorsing anti-realism across the board. Brian Ellis endorses a similar approach (though not specifically related to quantum mechanics) in his 2002.


I presented this paper in various forms at the 2006 APA Central Division, the University of St. Thomas (MN), Assumption College, Wake Forest University, Georgetown University, and the University of Virginia. I’m grateful to audience members at all of these places for excellent questions. This paper was the principal project I worked on during a fellowship at the Center for Philosophy of Religion, and I am very grateful for having had such a wonderful opportunity. I presented the paper at the Center’s famous weekly discussion group, where I received a great deal of helpful criticism. In particular, Mike Rea, Robert Garcia and Alvin Plantinga pressed me to make my view clearer. I hope I’ve managed to do so. I have received helpful written comments on the paper from E. J. Coffman, Michael Gorman, Alex Pruss, Jeffrey Green, Antonia Lolordo, Brie Gertler and a referee for this journal. Finally, Trenton Merricks read many drafts of this material, and offered innumerable suggestions for improvement: I’m most grateful for his generosity. An embarrassingly large number of people have helped me with this paper, and I’m afraid I may be inadvertently leaving some of them out of this acknowledgement: I hereby thank them and apologize for my faulty memory.


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