The Descriptive Challenge Against Physicalism
Below is a paper I wrote for publication but isn’t quite publishable for a journal (it’s been rejected several times namely for not adding anything new, apparently). But I think it lays out the argument for the irreducibility of consciousness clearly enough. In any case, I’m posting it here for your enjoyment. I hope it’s helpful to you!
One day, I was mindlessly scrolling through Facebook. I suddenly came across a video animating a series of molecules which confidently declared, “love. You are looking at love.” But I thought to myself, “really? Is that really love?” And the more I thought about it, the less it made sense. Could I describe love in terms of those molecules?
Over a decade later—in the present day, at the present moment in fact—I decided to write a paper on it. In this article, I intend to raise what I call “The Descriptive Challenge Against Physicalism.” I will argue:
P1) If consciousness is ontologically identical to brain-stuff, then it is the case that in giving a de re description of the former, one is giving a de re description of the latter.
P2) It is not the case that in giving a de re description of the former, one is giving a de re description of the latter.
C) Ergo, consciousness is not ontologically identical to brain stuff
This article will proceed as follows. First, I will highlight what I will call the “descriptive entailment” of the law of identity. Then, I will outline the descriptive challenge. In the third and largest section, I will rebut several anticipated objections from non-reductive physicalists, hoping to show why physicalists claims, if they remain truly physicalist, will fall prey to the Descriptive Challenge. It should be noted that I am limiting the discussion to a Non-Reductive Physicalist view of consciousness, such that human beings are said to be wholly material substances.
1. The Descriptive Entailment of the Law of Identity
First, we must specify the precise notion of identity used here in order to adequately anticipate objections of the “evening-star-morning-star” variety. Kripke famously argued that identity is a necessary relation. Since the mind and the body are not necessarily identical—we may have a possible world in which we have mind and not the body, or body and not the mind—they cannot be identical (Kripke 1980). But others have argued that this sort of argument fails owing to ignoring a relation of coincidence rather than identity. For instance, suppose one has a lump of clay that is molded into a statue. At t1, the statue and the lump of clay coincide; the latter utterly constitutes the former. But at t2, the statue loses its hand. Thus, while the lump of clay is broken, the statue remains a statue (Akiba 2000). Some use this sort of thinking to support a constitutional view of the mind-body relation, such that the brain constitutes the mind without being identical to it (Corcoran 2006). The notion of identity used here will need to be precise enough to furnish resources for meeting such proposals.
At root, the Law of Identity simply states that for any object A, if A is identical to B, such that A just is B, then whatever is true of A is true of B; thus, “everything is identical to itself, and nothing is ever identical except to itself” (Lewis 2001, 192–93). However, this definition will need some refinement owing to well-known puzzles. For instance, if Bobby believes that George Eliot wrote Middlemarch, but does not believe that Mary Ann Evans wrote Middlemarch, then it is true of “George Eliot” that “George Eliot is believed by Bobby to have written Middle March” and it is true of Mary Ann Evans that “Bobby does not believe Mary Ann Evans wrote Middlemarch.” Hence, this formulation would entail that George Eliot is not identical to Mary Ann Evans, which is false (Swartz 1970). Yet one might diffuse such challenges by appealing to de dicto vs de re knowledge, where the former deals with beliefs and the latter deals with the objects themselves (Chisholm 1976). On the other hand, one might think that the de dicto vs de re distinction might be better captured using other terms (Broackes 1986).
Thus, let’s formulate the Law of Identity as such: if A is B, then whatever is intrinsically true of A is intrinsically true of B, and vice-versa. By “intrinsically true”, I mean to speak of intrinsic properties as opposed to extrinsic ones (Harris 2018). Thus, whatever relation George Eliot bears to Bobby as opposed to Mary Ann Evan’s relation to Bobby will be irrelevant; in consideration of George Eliot and Mary Ann Evan’s intrinsic properties, they are identical. Intrinsic properties are notoriously difficult to define, as there are a wide range of schematization of these properties (Humberstone 1996). For the purposes of this paper, I will appropriate Vallentyne’s definition of intrinsic properties in terms of a conceptual contraction of a world down to a given object (1997). If I is an intrinsic property of x, then Ix if, when we remove all other objects in the world at t and contract, as it were, that world down to x, Ix still obtains. It is a feature of x in and of itself, in other words. For the sake of this argument, then, a de re description will be understood as one that describes the intrinsic properties of x.
Applied to consciousness, the argument runs as follows:
P1) If consciousness is ontologically identical to brain-stuff, then it is the case that in giving a de re description of the former, one is giving a de re description of the latter.
Which is just to say:
P1* (=P1, to my lights): If consciousness is ontologically identical to brain stuff, then it is the case that in giving a description of the former’s intrinsic properties (=giving a de re description of the former), one is giving a description of the intrinsic properties of the latter (=giving a de re description of the latter).
This formulation allows us to stave off evening-star-morning-star type objections. For the “appearing” of the evening star in the evening pertains to an extrinsic property (e.g. it appears in Earth’s sky in a given way at a given time). Descriptions of the evening star qua the evening star—insofar as this is understood in differentiating terms from the morning star—will not count as a description of intrinsic properties, and hence a de re description. Whether one agrees or not with my use of the phrase “de re description” here, while perhaps interesting, is nevertheless irrelevant to my overall argument.
We might symbolize the argument as such. Let D(x) denote a “de re description of x” (as understood above):
(x = y) > (D(x) = D(y))
That is, if x is identical to Y, then if a de re description of x is given, that same de re description of y is given. In other words, in describing the intrinsic properties of x, one is describing the intrinsic properties of y given the identity of x and y.
To show this, suppose I’ve lost my dog Maya one day. I see a dog in the distance, which I will call “Fido”. If Fido is Maya, then in describing the intrinsic properties of Fido, I am in fact describing the intrinsic properties of Maya. Hence, even if Fido is missing a tooth since the last time I’ve seen Maya, then it will be the case that in describing Fido’s “missing a tooth”, I am describing Maya’s “missing a tooth”. Let us call this the “Descriptive Entailment of Identity” (DE). Applied to consciousness, let x denote “instance of consciousness” and y denote “constitutive brain-stuff material”. If consciousness is brain-stuff, then in describing the intrinsic properties of the former, one must be describing the intrinsic properties of the latter.
2. The Descriptive Problem
But here’s the problem: a de re description of the brain doth not a de re description of consciousness make. To show this, let us tell a story.
Mary the T-Swift fan is thrilled to attend the Eras tour. She has volunteered for an experiment undertaken by overeager physicalist neuroscientists who hook up her brain to a fancy contraption which perfectly maps and represents her brain to the neuroscientists in their lab. When Taylor Swift sings, “you belong with me-he-he”, they obtain a crystal clear video-sequence of Mary’s brain and neural activity, and study that particular time segment (let’s say tm). After the concert, Mary approaches the neuroscientists during that time-segment and asks them to describe “what Taylor Swift sounded like to Mary during tm” only by describing intrinsic properties of the neural-patterns during Mary’s listening to tm. Note: Mary is not assuming that the scientists have never heard of Taylor Swift, and they may even know that Mary heard Taylor Swift sing “you belong to me” at tm. The question is whether they can describe the intrinsic properties of Mary’s experience—the qualia of hearing Taylor Swift at tm—by describing the intrinsic properties of the neural brain-stuff they see perfectly portrayed before them. I don’t think they can. If they rattle off facts about the neural patterns in Mary’s brain at tm, Mary will say something like, “that doesn’t describe what T-Swift sounded like to me at all.”
Initially, non-reductive physicalists—those who believe that the mental is nothing over and above the physical and yet is ontologically irreducible to the physical (Wilson 2010)—might think they are immune to this sort of argument. However, they are not. Consider the constitution view of non-reductive physicalism. If we imagine a bronze statue of Athena, the statue is materially the self-same object as the lump of bronze that constitutes it. Yet if part of that lump is replaced with, say, nickel, then the statue of Athena remains while the lump of bronze does not. This demonstrates a kind of non-identity of the statue with its physical constituent, even though its physical stuff is wholly continuous with the statue. Along these lines, Corcoran argues that while the brain-stuff is wholly the stuff of consciousness, consciousness cannot be reduced to this brain stuff (Corcoran 2006, 65–82). But of course, the statue is identical to a formal arrangement of the bronze lump. Hence, mutatis mutandis, in describing the intrinsic properties of the formal arrangement of brain stuff, one should be describing the intrinsic properties of consciousness. This same problem besets constitution views found in (Pereboom 2017). In describing the intrinsic properties of a constituent of x, one is describing x’s intrinsic properties relative to that constituent.
Here’s the upshot. If Freddy is walking through a garden and smelling roses, Susie cannot accurately describe what it’s like for Freddy to smell roses (the qualia of smelling roses) by simply describing the alleged physical constituent. She does not even get close to giving us such an account. This raises a problem, since a physicalist is committed to the claim that that all conscious experience is ontologically nothing over and above the physical. We can apply this thinking to the qualia of sights, sounds, tastes, etcetera. Now, a physicalist might say “well you are describing an intrinsic property of consciousness, just a non-experiential intrinsic property of consciousness.” Yet to say that Susie is describing a non-experiential intrinsic property of experience is to say that Susie is describing some non-experienced aspect of Freddy’s experience. In other words, she’s describing something internal to Freddy’s experience that—to Freddy—is not internal to that experience. But to claim that x is intrinsic to Freddy’s experience without being internal or part of that experience seems like a contradiction. Ergo, by modus tolens, consciousness is not ontologically identical to brain-stuff.
But of course, constitutional NRP claims are not the only kinds of NRP claims. We address these in section 3.
3. Assessing NRP Claims in Light of the Descriptive Challenge
So far, I doubt defenders of NRP will find the above argument plausible. Hence, we will need to respond to NRP claims in light of the Descriptive Challenge to see why they fall prey to it.
First, one might describe consciousness in terms of functional properties (F) which physical structures realize. Thus, functional properties are claimed not to be physical properties (P), but rather that F obtains in virtue of P (Levine 2004, 44–45). So for any physical token x and mental token y, Px > Fy, where Fy is the functionally realized aspect of Px. But this “in virtue of” move in and of itself is not sufficient for the Non-Reductive Physicalist to claim their view as a view of physicalism (neither is “supervenience” alone for that matter—see (Haug 2011; Wilson 2005)). For instance, we might conceive of a world in which substance dualism (as defined in Rickabaugh and Moreland 2024, 14) is true, and yet consciousness is deterministically constrained by a physical base. That is, there is no change in consciousness without there being a logically prior change in the microphysical base by a psychophysical law of some sort, so that even though consciousness is an immaterial substance, its changes wholly depend on logically prior physical changes. This view would qualify as a version of “non-reductive physicalism” under mere supervenience views and “in virtue of” views! This would even satisfy functionalist views of NRP insofar as the causal powers of consciousness are wholly determined by logically prior physical causal powers. But surely this isn’t a physicalist-acceptable thesis. Functional analyses of consciousness do not, in and of themselves, either entail or exclude physicalism (Himma 2005, 86). Thus, any view that purportedly agrees that “consciousness is not ontologically identical to brain stuff, but is still a physical substance” (or the like) by appeals to functional analyses need to specify how their views count as a version of physicalism.
Another strategy is to suggest that such views that criticize NRP for attributing non-physical properties to a physical thing rely on a constituent rather than a relational ontology. Hence, Eric Yang suggests that, under a relational ontology, a substance has a property by virtue of exemplifying that property rather than that property’s being a constituent of the substance. Since the material substance of brain-stuff exemplifies consciousness (rather than being constituted by it), one can hold that it is a physical thing—since it is a physical thing (brain-stuff) which exemplifies the property of “being conscious” (Yang 2015). But this line of reasoning is unconvincing. Even if we admit a relational ontology, exemplification accounts must make sense of intrinsic as opposed to extrinsic predication of properties; mere exemplification does not tell us much about the way a property is exemplified in an object. For instance, I might exemplify the property of “being taller than my brother” or “being thought of by Steve”, but neither of these are intrinsic property-exemplifications. For this reason, it is likely to my mind that relational ontologies need to be supplemented with constitutional claims in order to account for the difference in intrinsic and extrinsic properties. If the non-reductive physicalist claims that consciousness is exemplified by the brain as something extrinsic to the brain, then this version of NRP, as argued above, is not sufficiently distinguishable from either strong emergentist or deterministic forms of substance dualism. If consciousness is exemplified by the brain as an intrinsic property, then it is liable to the descriptive challenge.
But of course, certain non-reductive physicalists might appropriate property dualism, according to which mental and physical properties are genuinely distinct and irreducible properties. A physicalist, in order to maintain physicalism, will need to maintain that the human substance is physical, of which non-physical (e.g. mental) properties can be genuinely and irreducibly predicated. Nancey Murphy famously tries to do this by appealing to top-down causation. According to her, a system which is constituted by microphysical things can, by virtue of the interaction of those things, exert influence on those things (Murphy 2006, 85–90) We might think of an airplane exerting influence on its constituent parts, or an ant colony as a whole constraining ants in that colony. But in Murphy’s example of an airplane, it is important to note that top-down causation is described entirely in terms of “new complex entities with the ability to use lower-level causal forces…in new ways to do new things”(Murphy 2010, 136). In the case of emergent entities like airplanes or ant colonies, such entities are identical to their material constituents plus patterns of behaviors and inter-relations between those constituents. But it certainly is not the case that the ant colony is thereby “ontologically irreducible”, but rather just is the inter-relating of material actors. Given this identity relation, per the descriptive entailment, the intrinsic properties of the ants-in-inter-relation just are the intrinsic properties of the ant colony, such that in describing the former one is describing the latter. Mutatis mutandis, the modus tollens set up above using the descriptive entailment would apply to such a conception of consciousness.
Yet there are formulations of NRP which will require me to modify the descriptive entailment above (while still applying the same basic insight). These accounts will generally involve some notion of realization. A statue of Athena, for instance, may be realized in a lump of bronze in the state of affairs constituted by a “bronze statue of Athena”. Realization is a kind of constitutive relation in which a realized property is constituted by a realizer which instantiates that property (Shoemaker 2011). A realized property will be, in general, a subset of the properties of the realizer, consisting in some physical property P realizing some mental property M. Jessica Wilson argues that we may even limit this realization to the token causal powers of M, such that it is only the token causal powers of M which is a proper subset of the token causal powers of P realizing M (Wilson 2011). What are we to make of such strategies? First, I will treat versions of NRP arguing that the realized properties of M are identical with either a subset of P realizing M, Then, I will treat causal accounts.
What makes versions of NRP which identify M as a realized property of P somewhat tricky is the notion of “multiple realizability.” Multiple realizability is the claim that some higher level property M might be realized in different Ps (P1, P2, and so forth) such that a token of M (M1) might have multiple physical realizers (P1 realizing M1, or P2 realizing M1 and so forth) (Putnam 2003, 429-440). Thus, since M1 might be multiply realized in P1,2,etc, it is not identical to any of those physical properties. While it may be true, however, that M would not be identical to P, nevertheless this is only true in the same way that the statue of Athena is not identical to the lump of bronze which constitutes it. Hence, we can reformulate the descriptive entailment along the following lines:
P1) If Y is realized in X, then X constitutes Y
P2) If X constitutes Y, then the intrinsic properties of X are intrinsic properties of Y (e.g. whether a subset or not)
P3) If the intrinsic properties of X are the intrinsic properties of Y (either a subset or not), then a de dicto description of X relative (in the sense defined above) is a de dicto description of Y.
C) If Y is realized in X, then a de dicto description of X is a de dicto description of Y
In defense of P2, consider the statue of Athena. If the statue of Athena is constituted by a bronze lump configured in a certain way, then the intrinsic properties of that bronze lump are, at least, a subset of the intrinsic properties of the statue when that lump is configured Athena-wise. P3) follows from the law of identity. It may be the case that a full de dicto description of X might only describe a subset of Y, and thus might not be a full de dicto description of Y, but that will not matter for the purposes of the argument.
Hence, let M denote mental tokens and P denote physical tokens.
P1) If M is realized in P, then P constitutes M
P2) If P constitutes M, then the intrinsic properties of P are intrinsic properties of M (e.g. whether a subset or not)
P3) If the intrinsic properties of P are intrinsic properties of M (either a subset or not), then a de dicto description (in the sense defined above) of P is a de dicto description of M.
C) If M is realized in P, then a de dicto description of P is a de dicto description of M
To this, we add the not-p premise defended above:
P4) It is not the case that a de dicto description P is a de dicto description of M
C2) It is not the case that M is realized in P
The same arguments I applied in the formulation of the descriptive entailment assuming the law of identity will apply here in defense of premise 4. One cannot describe Mary the T-Swift Fan’s experience of a given song by describing a profile of P’s intrinsic properties at the time of her listening to the song. In other words, a description of the intrinsic property profile of P does not a description of the intrinsic property profile M make.
What are we to make of causal accounts? It seems to me that, if the token causal powers of M are a proper subset of the token causal powers of P, then this would mean that the intrinsic properties of the token causal powers of M are intrinsic properties of the token causal powers of P, even if the former does not exhaust the latter. Thus, a de re description of the former would still be a de re description of the latter. But even so, contra Wilson’s claim that this suffices for a non-reductive physicalism, a physically-acceptable thesis must assert more than this. For on a deterministic view of substance dualism, one might arguably hold to this view while yet holding consciousness with respect to its non-causal powers is not a physical substance; but surely this cannot qualify as a version of physicalism!
4. Conclusion
Let’s take stock. The Descriptive Challenge flows from the claim that, if A is identical to B, then a de re description of A (in the sense defined above) will be a de re description of B on account of the former’s intrinsic properties being identical to the latter’s. Further, if X is a constituent of Y or is realized in Y, then the intrinsic properties of X will be the intrinsic properties of Y, and a de re description of X will be a de re description of Y (but not necessarily vice-versa in constitutional or realization cases). The Non-Reductive Physicalist might appeal to various strategies along property dualist lines, but then she will need to show why her version of NRP is distinguishable from a deterministic version of substance dualism, wherein the mind is a distinct substance from the brain even if determined in all its motions and actions by the brain. If physicalist and non-reductive physicalists cannot show that the intrinsic properties of consciousness are intrinsic properties of brain-states, then we should reject physicalist construals of the mind.
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Well if it doesn't lay out anything new, it must reiterate what's already been said, so it almost might as well be published, lol.