Causal Powers and the Necessity of Realization

Non-reductive physicalists hold that mental properties are realized by physical properties. The realization relation is typically taken to be a metaphysical necessitation relation. Here, I explore how the metaphysical necessitation feature of realization can be explained by what is known as ‘the subset view’ of realization. The subset view holds that the causal powers that are associated with a realized property are a proper subset of the causal powers that are associated with the realizer property. I argue that the said explanation of the metaphysical necessitation feature requires a careful treatment of the relationship between properties and causal powers.     

GUIDELINES FOR THEORIZING ABOUT REALIZATION

Realization can be roughly understood as a kind of role‐playing, a relationship between a property that plays a role and a property characterized by that role. This rough sketch previously received only moderate elaboration; recently, however, several substantive theories of realization have been proposed. But are there any general constraints on a theory of realization? What is a theory of realization supposed to accomplish? I first argue that a view of realization is viable, in part, to the extent that physical realization under that view explains or accounts for why instances of realized properties are necessitated by how things are physically in a modally strong sense. In this sense, I claim that physical realization should explain physical supervenience. I then call into question two alternative desiderata and raise a challenge for attempts to explicate realization in terms of isomorphism or analogy. Finally, I explain how a causal‐functional account of realization, as well as less demanding accounts, can meet the preferred desideratum.     

How Superduper Does a Physicalist Supervenience Need to Be?

The standard formulations of the supervenience relation present the supervenience of one set of properties on another in terms of property correlations, without placing any constraints on the dependency relation concerned. This does not ensure that properties supervening upon phys-icalistically acceptable base properties are not themselves emergent in a way at odds with materialism. So physicalism needs 'superdupervenience'. I argue that, where supervenient and base properties are instantiated in the same individuals, Horgan's requirement of robust explanation is neither sufficient nor necessary for superdupervenience. His paradigm case is compatible with the supervenient property's being emergent. This and other unacceptable possibilities may be ruled out by means of a metaphysical constraint on the supervenience relation, which must be internal. Each individual causal power in the set associated with a given supervenient property must be numerically identical with a causal power in the set associated with its base property. Satisfying this condition is all that is needed to render supervenience superduper. In fact a wide variety of non-reductive physicalist accounts are implicitly or explicitly designed to meet this condition, and so are more similar than they seem.     

Properties,Powers, and the Subset Account of Realization

According to the subset account of realization, a property, F, is realized by another property, G, whenever F is individuated by a non‐empty proper subset of the causal powers by which G is individuated (and F is not a conjunctive property of which G is a conjunct). This account is especially attractive because it seems both to explain the way in which realized properties are nothing over and above their realizers, and to provide for the causal efficacy of realized properties. It therefore seems to provide a way around the causal exclusion problem. There is reason to doubt, however, that the subset account can achieve both tasks. The problem arises when we look closely at the relation between properties and causal powers, specifically, at the idea that properties confer powers on the things that have them. If realizers are to be ontically prior to what they realize, then we must regard the conferral of powers by properties as a substantive relation of determination. This relation of conferral is at the heart of a kind of exclusion problem, analogous to the familiar causal exclusion problem. I argue that the subset account cannot adequately answer this new exclusion problem, and is for that reason ill‐suited to be the backbone of a non‐reductive physicalism.     

Emergence,Supervenience, and Realization

In the first section of this paper, I articulate Jaegwon Kim's argument against emergent down ward causation. In the second section, I canvas four responses to Kim's argument and argue that each fails. In the third section, I show that emergent downward causation does not, contra Kim, entail overdetermination. I argue that supervenience of emergent upon base properties is not sufficient for nomological causal relationsbetween emergent and base properties. What sustains Kim's argument is rather the claim that emergent properties realized by base properties can have no causal powers distinct from those base properties. I argue that this is false.     

Epiphenomenal Properties

What is an epiphenomenal property? This question needs to be settled before we can decide whether higher-level properties are epiphenomenal or not. In this paper, I offer an account of what it is for a property to have some causal power. From this, I derive a characterization of the notion of an epiphenomenal property. I then argue that physically realized higher-level properties are not epiphenomenal, because laws of nature impose causal similarities on the bearers of such properties, and these similarities figure as powers in the causal profiles of these properties.     

Causal Powers, Realization, and Mental Causation

Sydney Shoemaker has attempted to save mental causation by a new account of realization. As Brian McLaughlin argues convincingly, the account has to face two major problems. First, realization does not guarantee entailment. So even if mental properties are realized by physical properties, they need not be entailed by them. This is the first, rather general metaphysical problem. A second problem, which relates more directly to mental causation is that Shoemaker must appeal to some kind of proportionality as a constraint on causation in order to avoid redundant mental causation. I argue that, in addition, a “piling problem” arises, since causal powers seem to be bestowed twice. Then, I try to sketch an alternative view of the relation between causal powers and properties—a reductionist view—which fares better on some accounts. But it may have to face another and, perhaps, serious problem, the “problem of the natural unity of properties”. Finally, I will pose a question about the relation between causal powers and causation.

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Shoemaker's Analysis of Realization: A Review

Sydney Shoemaker has been arguing for more than a decade for an account of the mind–body problem in which the notion of realization takes centre stage. His aim is to provide a notion of realization that is consistent with the multiple realizability of mental properties or events, and which explains: (i) how the physical grounds the mental; and (ii) why the causal work of mental events is not screened off by that of physical events. Shoemaker's proposal consists of individuating properties in terms of causal powers, and defining realization as a relation of inclusion between sets of causal powers. Thus, as the causal powers that define a mental property are a subset of the causal powers that characterize a physical property, it can be said that physical properties realize mental properties. In this paper we examine the physicalist credentials of Shoemaker's mind–body theory in relation to three important issues: the direction of the relation of dependence that the theory is committed to; the possibility of mental properties existing without being anchored by physical properties; and the compatibility of the theory with the causal closure of the physical world. We argue that Shoemaker's theory is problematic in all three respects. After that we consider whether the theory should count as a mind–body theory at all, given that it seems to be committed to a distorted view of mental properties.     

Rich Egalitarianism,Ordinary Politics,and the Demands of Justice

In this paper I develop a theory of the physical realization of higher-level properties. I argue that physical realization is in an important sense indirect, and that at each level causal relations are crucial to realizing next-level phenomena. My account makes it intelligible how higher-level properties can be realized by wide stretches of physical reality without the inter-level dependence becoming weak, or global; it also explains how both physicalism and non-reductivism can be true.     

Do Extrinsic Dispositions Need Extrinsic Causal Bases?

In this paper, I distinguish two often‐conflated theses—the thesis that all dispositions are intrinsic properties and the thesis that the causal bases of all dispositions are intrinsic properties—and argue that the falsity of the former does not entail the falsity of the latter. In particular, I argue that extrinsic dispositions are a counterexample to first thesis but not necessarily to the second thesis, because an extrinsic disposition does not need to include any extrinsic property in its causal basis. I conclude by drawing some general lessons about the nature of dispositions and their relation to their causal bases.     

Shoemaker on emergence

Sydney Shoemaker has recently given an account of emergent properties according to which emergent properties are a special type of structural property and the determination relation holding between emergent properties and their base properties is one of “mere nomological supervenience.” According to Shoemaker, emergent properties are what he calls type-2 microstructural properties, whereas physical properties are type-1 microstructural properties. After highlighting the advantages of viewing emergent properties as a special class of microstructural properties, I show how according to his own causal theory of properties type-2 microstructural properties actually reduce to type-1 microstructural properties, and thus do not truly count as emergent. I then suggest an alternative view according to which emergent properties are actually a third type of microstructural property, one not considered by Shoemaker. I conclude with reflections why we might view the dependence relation between emergent properties and their physical base properties as a causal relation rather than one of mere supervenience.     

Can determinable properties earn their keep?

Sydney Shoemaker’s ‘Subset Account’ offers a new take on determinable properties and the realization relation as well as a defense of non-reductive physicalism from the problem of mental causation. At the heart of this account are the claims that (1) mental properties are determinable properties and (2) the causal powers that individuate a determinable property are a proper subset of the causal powers that individuate the determinates of that property. The second claim, however, has led to the accusation that the effects caused by the instantiation of a determinable property will also be caused by the instantiation of the determinates of that property—so instead of solving the problem of mental causation, the Subset Account ends up guaranteeing that the effects of mental properties (and all other types of determinable property) will be causally overdetermined! In this paper, I explore this objection. I argue that both sides in this debate have failed to engage the question at the heart of the objection: Given that both a determinable property and its determinates have the power to cause some effect (E), does it follow that both will actually cause E when the relevant conditions obtain? To make genuine progress towards answering this question, we need to take a serious look at the metaphysics of causation. With the debate properly reframed and issues about the metaphysics of causation front and center, I explore the question of whether the Subset Account is doomed to result in problematic causal overdetermination.     

How does downward causation exist?—A comment on Kim’s elimination of downward causation

The importance of downward causation lies in showing that it shows that functional properties such as mental properties are real, although they cannot be reduced to physical properties. Kim rejects nonreductive physicalism, which includes leading functionalism, by eliminating downward causation, and thereby returns to reductionism. In this paper, I make a distinction between two aspects of function—functional meaning and functional structure and argue that functional meaning cannot be reduced to the physical level whereas functional structure can. On this basis, I further distinguish between the integer of the function, which includes the functional meaning and the functional structure, and the whole of the functional realization, and also among the strong, medial, and weak supervenience relations. So-called downward causation is indeed the relationship between the whole of the functional realization and its physical realizer, which is a whole-part relation instead of a relation between levels. As a result of understanding downward causation in this way and abandoning the principle of the causal closure of the physical world, Kim’s argument becomes invalid and nonreductive functionalism, justified.     

Taking realization seriously: no cure for epiphobia

The realization relation that allegedly holds between mental and physical properties plays a crucial role for so-called non-reductive physicalism because it is supposed to secure both the ontological autonomy of mental properties and, despite their irreducibility, their ability to make a causal difference to the course of the causally closed physical world. For a long time however, the nature of realization has largely been ignored in the philosophy of mind until a couple of years ago authors like Carl Gillett, Derk Pereboom, or Sydney Shoemaker proposed accounts according to which realization is understood against the background of the so-called ‘causal theory of properties’. At least partially, the hope was to solve the problem of mental causation, in particular the kind of causal exclusion reasoning made famous by Jaegwon Kim, in a way acceptable to non-reductive physicalists. The paper asks whether a proper explication of the realization relation can indeed help explain how physically realized mental properties can be causally efficacious in the causally closed physical world and argues for a negative answer: it is important for the non-reductive physicalist to understand what exactly the realization relation amounts to, but it does not solve the problem of mental causation.     

Mental Causation and the Supervenience Argument

One of several problems concerning the possibility of mental causation is that the causal potential of a supervenient property seems to be absorbed by its supervenience base if that base and the supervenient property are not identical. If the causal powers of the supervenient property are a proper subset of the causal powers of the supervenience base then, according to the causal individuation of properties, the supervenience base seems to do all the causal work and the supervenient property appears to be futile. Against this consequence it is possible to argue, first, that the relevant properties of causes must be in some sense proportional to the relevant properties of their effects and, second, that the principle of causal closure serving as a premise in the supervenience argument is probably false. The constraint that the relevant properties of causes should be proportional to the relevant properties of their effects together with the falsity of the closure principle leads to a restoration of the causal efficacy of supervenient properties.

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Realization and Multiple Realization,Chicken and Egg

A common view is that the truth of multiple realization—e.g., about psychological states—entails the truth of functionalism. This is supposed to follow because what is multiply realized is eo ipso realized. I argue that view is mistaken by demonstrating how it misrepresents arguments from multiple realization. In particular, it undermines the empirical component of the arguments, and renders the multiplicity of the realization irrelevant. I suggest an alternative reading of multiple realizability arguments, particularly in philosophy of psychology. And I explain the proper way to understand the relation between realization and multiple realization.     

The cost of forfeiting causal inheritance

Jaegwon Kim’s causal inheritance principle says that the causal powers of a mental property instance are identical with the causal powers of its particular physical realizer. Sydney Shoemaker’s subset account of realization is at odds with Kim’s principle: it says that a mental property instance has fewer causal powers than Kim’s principle entails. In this paper, I argue that the subset account should be rejected because it has intolerable consequences for mental causation, consequences that are avoided by accepting causal inheritance. I develop my argument in part by drawing on one of the central debates that has arisen regarding the extended mind hypothesis defended by Andy Clark and David Chalmers.     

Realization and the metaphysics of mind1

According to a familiar view in philosophy of mind, mental states or properties are realized by physical states or properties but are not identical to them. This view is often called realization physicalism. But what is realization? I argue that recent approaches to realization, represented by Carl Gillett's ‘dimensioned’ view, fail to acknowledge some textbook cases of realization. I also argue Gillett's account in particular admits realization relations that should not count if realization physicalism is to be distinguished from its competitors in the usual ways. I offer my own account of realization, and argue that it is superior not only in passing the above tests but also in its utility for answering questions about multiple realizability.     

The Generalization Problem and the Identity Solution

For some time now, Jaegwon Kim has argued that irreducible mental properties face the threat of causal inefficacy. The primary weapon he deploys to sustain this charge is the supervenience/exclusion argument. This argument, in a nutshell, states that any mental property that irreducibly supervenes on a physical property is excluded from causal efficacy because the underlying physical property takes care of all of the causal work itself. Originally intended for mental properties alone, it did not take long for his critics to suggest the argument generalizes across all of the special science properties as well. Kim responds in two different ways to the generalization problem. The first response, which I call the higher-level solution, is ably dismissed by numerous critics. The second response, which I call the identity solution, has not faced comparable scrutiny. In this paper I argue that the identity solution faces numerous problems of its own.