Is conceptual analysis required for reductive explanation? If there is no a priori entailment from microphysical truths to phenomenal truths, does reductive explanation of the phenomenal fail? We say yes . Ned Block and Robert Stalnaker say no.

This much-anticipated book is a detailed elaboration and defense of Levine’s influential claim that there is an “explanatory gap” between the mental and the physical.

The explanatory gap . Consciousness is a mystery. No one has ever given an account, even a highly speculative, hypothetical, and incomplete account of how a physical thing could have phenomenal states. Suppose that consciousness is identical to a property of the brain, say activity in the pyramidal cells of layer 5 of the cortex involving reverberatory circuits from cortical layer 6 to the thalamus and back to layers 4 and 6,as Crick and Koch have suggested for visual consciousness. .) (...) Still, that identity itself calls out for explanation! Proponents of an explanatory gap disagree about whether the gap is permanent. Some say that we are like the scientifically naive person who is told that matter = energy, but does not have the concepts required to make sense of the idea. If we can acquire these concepts, the gap is closable. Others say the gap is uncloseable because of our cognitive limitations. Still others say that the gap is a consequence of the fundamental nature of consciousness. (shrink)

Recently much has been made of the grounding relation, and of the idea that it is intimately tied to fundamentality. If A grounds B, then A is more fundamental than B (though not vice versa ), and A is ungrounded if and only if it is fundamental full stop—absolutely fundamental. But here is a puzzle: is grounding itself absolutely fundamental?

Horgan (1993) proposed that "superdupervenience" - supervenience preserving physicalistic acceptability - is a matter of robust explanation. I argued against him (1999) that (as nearly all physicalist and emergentist accounts reflect) superdupervenience is a matter of Condition on Causal Powers (CCP): every causal power bestowed by the supervenient property is identical with a causal power bestowed by its base property. Here I show that CCP is, as it stands, unsatisfactory,for on the usual understandings of causal power bestowal, it is trivially (...) satisfied or falsified. I offer a revision of CCP which incorporates the evident fact that causal powers are grounded in fundamental forces. (shrink)

A purely metaphysical formulation of physicalism is surprisingly elusive. One popular slogan is, 'There is nothing over and above the physical'. Problems with this arise on two fronts. First, it is difficult to explain what makes a property 'physical' without appealing to the methodology of physics or to particular ways in which properties are known. This obviously introduces epistemic features into the core of a metaphysical issue. Second, it is difficult to cash out 'over-and-aboveness' in a way that is rigorous, (...) metaphysically pure and extensionally apt for the purposes of the debate. In this paper I will touch on the first problem, but I wish to focus on the second. In particular, I will focus on the claim that supervenience theses cannot define physicalism because they allow classical emergentist dualism through the physicalist door [Horgan 1993; Kim 1998; Wilson 2005]. I will argue that when the relevant supervenience thesis is metaphysical, emergentism is excluded. Against recent arguments to the contrary, I maintain that this is the case even given necessitarianism about natural laws [Wilson 2005]. I will argue that a necessitarian with emergentist sympathies will be forced either into a type of quasi-panpsychism, where our basic physical properties contain the illicit seeds of mentality at their core, or she will be forced to admit that emergence laws are not necessary after all. Either way, the combination of necessitarianism and emergentism does not provide a counterexample to supervenience physicalism. (shrink)

This slim volume is sure to provoke. The topics include physicalism, the theory of color, and metaethics, but the primary focus is metaphilosophical: Jackson aims to defend the use of conceptual analysis as a tool for doing “serious metaphysics.”.

The physicalist thesis that all entities are nothing over and above physical entities is often interpreted as appealing to a supervenience-based account of "nothing over and aboveness”, where, schematically, the A-entities are nothing over and above the B-entities if the A-entities supervene on the B-entities. The main approaches to filling in this schema correspond to different ways of characterizing the modal strength, the supervenience base, or the supervenience connection at issue. I consider each approach in turn, and argue that the (...) resulting formulation of physicalism is compatible with physicalism’s best traditional rival: a naturalist emergentism. Others have argued that supervenience-based formulations of physicalism fail. My aim here, besides addressing the full spectrum of supervenience-based approaches, is to show how certain philosophical and scientific theses concerning naturalism, properties, and laws give us new reasons to think that supervenience-based formulations of physicalism are untenable. (shrink)

I argue that an adequate account of non-reductive realization must guarantee satisfaction of a certain condition on the token causal powers associated with (instances of) realized and realizing entities---namely, what I call the 'Subset Condition on Causal Powers' (first introduced in Wilson 1999). In terms of states, the condition requires that the token powers had by a realized state on a given occasion be a proper subset of the token powers had by the state that realizes it on that occasion. (...) Accounts of non-reductive realization conforming to this condition are implementing what I call 'the powers-based subset strategy'. I focus on the crucial case involving mental and brain states; the results may be generalized, as appropriate. I first situate and motivate the strategy by attention to the problem of mental causation; I make the case, in schematic terms, that implementation of the strategy makes room (contra Kim 1989, 1993, 1998, and elsewhere) for mental states to be ontologically and causally autonomous from their realizing physical states, without inducing problematic causal overdetermination, and compatible with both Physicalism and Non-reduction; and I show that several contemporary accounts of non-reductive realization (in terms of functional realization, parthood, and the determinable/determinate relation) are plausibly seen as implementing the strategy. As I also show, implementation of the powers-based strategy does not require endorsement of any particular accounts of either properties or causation---indeed, a categoricalist contingentist Humean can implement the strategy. The schematic location of the strategy in the space of available responses to the problem of mental (more generally, higher-level) causation, as well as the fact that the schema may be metaphysically instantiated, strongly suggests that the strategy is, appropriately generalized and instantiated, sufficient and moreover necessary for non-reductive realization. I go on to defend the sufficiency and necessity claims against a variety of objections, considering, along the way, how the powers-based subset strategy fares against competing accounts of purportedly non-reductive realization in terms of supervenience, token identity, and constitution. (shrink)

Note: this is the first published presentation and defense of the 'proper subset strategy' for making sense of non-reductive physicalism or the associated notion of realization; this is sometimes, inaccurately, called "Shoemaker's subset strategy"; if people could either call it the 'subset strategy' or better yet, add my name to the mix I would appreciate it. Horgan claims that physicalism requires "superdupervenience" -- supervenience plus robust ontological explanation of the supervenient in terms of the base properties. I argue that Horgan's (...) account fails to rule out physically unacceptable emergence. I rather suggest that this and other unacceptable possibilities may be ruled out by requiring that each individual causal power in the set associated with a given supervenient property be numerically identical with a causal power in the set associated with its base property. I go on to show that a wide variety of physicalist accounts, both reductive and non-reductive, are implicitly or explicitly designed to meet this condition, and so are more similar than they seem. In particular, non-reductive physicalism accounts typically appeal to a relation plausibly ensuring that the powers of a higher-level property are a proper subset of those of its physical base property. (shrink)

It has been suggested that many philosophical theses—physicalism, normative naturalism, phenomenalism, and so on—should be understood in terms of ground. Against this, Ted Sider (2011) has argued that ground is ill-suited for this purpose. Here I develop Sider’s objection and offer a response. In doing so I develop a view about the role of ground in philosophy, and about the content of these distinctively philosophical theses.

G. E. Moore argues that goodness is an intrinsic non-natural property that supervenes irreducibly on the intrinsic natural properties of its bearers. Accordingly, it is often supposed that “Moorean” supervenience is incompatible with physicalism, a naturalistic thesis. In this paper I argue that Moorean supervenience is not in itself incompatible with physicalism, Moore’s ethical non-naturalism notwithstanding. Understanding why will help us to better appreciate the full range of resources available to physicalists.

A prominent objection to supervenience physicalism is that a definition of physicalism in terms of supervenience allows for physicalism to be compatible with nonphysicalist outlooks, such as certain forms of emergentism. I take as my starting point a recent defense of supervenience physicalism from this objection. According to this line of thought, the subvenient base for emergent properties cannot be said to be purely physical; rather, it is “polluted” with emergent features in virtue of necessarily giving rise to them. Thus, (...) if emergentism is true, it is false that everything supervenes on physical properties. I argue that this gives way to a new challenge for supervenience physicalism. The challenge, roughly, is to distinguish the emergentist’s “polluted” base from a physical supervenience base; that is, to give conditions under which the subvenient base is not “polluted” by supervenient properties. The problem, I argue, is that it is hard to see how this can be done without collapsing supervenience physicalism into alternative approaches to physicalism. I thus argue that if the present defense of supervenience physicalism succeeds in defending the adequacy of a supervenience-based definition of physicalism, it does so by compromising its uniqueness. (shrink)

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. (shrink)

Twenty years ago, Richard Boyd suggested that physicalism could be formulated by appeal to a notion of realization, with no appeal to the identity of the non-physical with the physical. In (Melnyk 2003), I developed this suggestion at length, on the basis of one particular account of realization. I now ask what happens if you try to formulate physicalism on the basis of other accounts of realization, accounts due to LePore and Loewer and to Shoemaker. Having explored two new formulations (...) of physicalism, I conclude that my 2003 formulation remains the most promising. (shrink)

A review of Andrew Melnyk's _A Physicalist Manifesto_ (Cambridge: CUP, 2003).

Supervenience has provided a way for nonreductive materialists to explain how the mental can be physically irreducible but still physically respectable. In recent years, doubts about this research program have emerged from a number of quarters. Consequently, Terence Horgan has argued that nonreductive materialists must appeal to an upgraded "superdupervenience," if supervenience is to do any materialist work. We argue that nonreductive materialism cannot meet this challenge. Superdupervenience is impossible.

How should the metaphysical hypothesis of materialism be formulated? What strategies look promising for defending this hypothesis? How good are the prospects for its successful defense, especially in light of the infamous "hard problem" of phenomenal consciousness? I will say something about each of these questions.

First, we shall consider the distinction as set forth in Principia. Next, on the basis of what Moore says there, a view as to the nature of universals will be attributed to him. This view will provide the ground for a radical distinction between natural and non-natural properties. But it will not quite jibe with other things he says at a slightly later period. Nor will it be clear why he holds to such a view of universals. Finally we shall (...) consider a very early paper of Moore's, written just prior to Principia. An analysis of this paper will reveal a rather strange and complex ontology implicit in it. This, in turn, will show the source of the ontology of Principia; why the ontology attributed to him in Principia does not jibe with other things he says; and the origin of the notion of non-natural properties. (shrink)

A compelling idea holds that reality has a layered structure. We often disagree about what inhabits the bottom layer, but we agree that higher up we find chemical, biological, geological, psychological, sociological, economic, /etc./, entities: molecules, human beings, diamonds, mental states, cities, interest rates, and so on. How is this intuitive talk of a layered structure of entities to be understood? Traditionally, philosophers have proposed to understand layered structure in terms of either reduction or supervenience. But these traditional views face (...) well-known problems. A plausible alternative is that layered structure is to be explicated by appeal to explanations of a certain sort, termed / grounding explanations/. Grounding explanations tell us what obtains in virtue of what. Unfortunately, the use of grounding explanations to articulate the layered conception faces a problem, which I call /the collapse/. The collapse turns on the question of how to ground the facts stated by the explanations themselves. In this paper I make a suggestion about how to ground explanations that avoids the collapse. Briefly, the suggestion is that the fact stated by a grounding explanation is grounded in its /explanans/. (shrink)