On the pedigree of the ‘subset view’ of realization
University of Toronto
The ‘proper subset view’ of physical realization, according to which it is key to non-reductive realization that the powers of higher-level and lower-level features stand in a proper subset relation, is often credited to Sydney Shoemaker, citing his 2000/2001 paper ‘Realization and Mental Causation’ (first published in 2000 in the Proceedings of the 20th World Congress in Philosophy, which took place in August 1998, and reprinted in revised form in Physicalism and Its Discontents, Gillet and Loewer, eds., in 2001). Correspondingly, the view is frequently described as ‘Shoemaker’s subset account of realization’, ‘Shoemaker’s proper subset view’, ‘Shoemaker’s strategy for non-reductive physicalists’, and so on.
However, I was the first person to present and defend the subset view, in 'How Superduper does a Physicalist Supervenience Need to Be?' (Philosophical Quarterly, 1999), based on a term paper of the same name that I wrote as a third-year graduate student at Cornell in April-May 1998. I don’t take credit for the basic idea---like Shoemaker, I credit this to Michael Watkins, who suggested it in the course of a 1996 NEH Seminar in the Metaphysics of Mind run by John Heil, that I attended and that Shoemaker visited; Watkins’s suggestion was then concurrently developed by both Shoemaker and me. But again, I was the first to present and develop it in print, and many of the arguments that are attributed solely to Shoemaker can be found in my original paper. Moreover, since 1998/9 I've refined and developed my conception of the approach, in my 2001 dissertation (Physicalism, Emergentism, and Fundamental Forces) and in several papers, including 'Supervenience-based Formulations of Physicalism' (Nous 2005), ‘Determination, Realization, and Mental Causation’ (Philosophical Studies 2009), 'Non-reductive Physicalism and Degrees of Freedom' (BJPS 2010), 'Non-reductive Physicalism and the Powers-based Subset Strategy' (Monist 2011), and ‘Metaphysical Emergence: Weak and Strong’ (forthcoming).
So I have at least an equal claim to being a progenitor and defender of the subset view. However, many authors do not cite me at all. And when I am cited, my work frequently fails to be discussed in the main text, even when arguments very similar to those being discussed first appeared in my work, and even when my work contains explicit responses to objections being discussed in the main text.
Besides the subset view, I have at least an equal claim to credit for two other theses associated with this view, which again are proposed and extensively defended in my work, starting with my 1998/9. First is that the proper subset approach to realization provides a basis for a ‘compatibilist’ solution to the problem of mental (higher-level) causation; second is that Yablo’s determinable-based account of realization (‘Mental Causation’, Philosophical Review 1992) can be profitably interpreted as involving satisfaction of the subset condition on powers. Here again, Shoemaker’s work is commonly cited, whereas mine almost never is.
There is one final, more general thesis for which I deserve, but haven’t so far gotten, credit. In my 1999 paper, I proposed and defended attention to powers, as opposed to either supervenience relations or explanatory relations (such as Horgan’s superdupervenience’), as providing a properly metaphysical basis for characterizing the primary differences between emergentist, reductive physicalist, and non-reductive physicalist accounts of seemingly higher-level features. To the extent that there has been a ‘metaphysical turn’ in understanding dependence relations, my paper was certainly in on the ground floor, and deserves to be acknowledged as such. Certainly I was calling attention to the need for such relations to be understood in metaphysical rather than merely modal or epistemic terms long before, e.g., Fine, Schaffer, or Rosen.
Below I flag a couple of key passages and sections from my 1999 paper, relevant to these theses; again, the view has undergone some refinement in my later work (e.g., I now formulate the proper subset condition in terms of token powers, on a given occasion).
In my 1999 paper, I started by motivating, by attention to the problem of mental (more generally, higher-level) causation, the need for all varieties of physicalism to impose the following condition on causal powers:
Condition on Causal Powers (CCP): Each individual causal power associated with a supervenient property is numerically identical to a causal power associated with its base property.
I said, after having discussed how robust (British) emergentists would likely respond to the problem:
The emergentist response to the possibility of mental causal overdetermination is to deny that the physical is causally closed [...] and to assert that mental properties have causal powers not possessed by any physicalistically acceptable base properties. Physicalists committed to the causal efficacy of mental properties, as well as to the thesis that mental properties are “nothing over and above” mental properties (that is, most physicalists) cannot take the emergentist route. They cannot allow that mental properties have any causal powers that are completely different from their physicalistically acceptable base properties (this violates physicalism), nor can they allow that mental properties have the same, but still numerically distinct, causal powers as their base properties (this leads to causal overdetermination). The remaining option for such physicalists is to hold, in contrast to emergentists, that every individual causal power of a mental property is identical to a causal power of a physicalistically acceptable base property. (As will be made clear later, this restriction does not entail that mental properties are identical to their base properties.) (41)
I then went on to note that imposition of CCP was compatible with a distinctively non-reductive physicalist account of the relation at issue, if the powers of the higher-level feature were a proper subset of those of the lower-level feature:
Conceiving of a physicalist supervenience in terms of causal powers would do more than allow physicalists to determinine whether a given property superdupervened on another. It would also provide a blueprint for non-reductivists to establish that a given supervenient property was distinct from its base property, by showing that the base property had (one or more) different causal powers than the supervenient property. In this case the set of causal powers associated with the supervenient property would be a proper subset of the set of causal powers associated with the base property, thus providing a clear-cut account (which has too often been lacking) of how a higher-level (say, mental) property could be distinct from, and yet “nothing over and above”, a lower-level physicalistically acceptable property.[Footnote: This observation is due to Michael Watkins, who used it (in John Heil’s 1996 NEH seminar in the Metaphysics of Mind) in service of a non-reductive physicalist solution to the problem of mental causation.] Attention to causal powers would also go some distance towards enabling physicalists to establish that a given property was multiply realizable, by showing that the causal powers associated with a given supervenient property were subsets, proper or improper, of the causal powers of properties in more than one supervenience base set. If we are looking for markers that can do some metaphysical work, causal powers seem to be just the ticket. (45)
Finally, I considered three non-reductive physicalist accounts of the realization relation, and argued that the relation in each case arguably satisfies the condition on powers in question, including Yablo’s (1992) suggestion that higher-level features are determinables of physical determinates, Pettit’s (1995) account of physicalism and associated ‘dot-shape’ analogy, and Shoemaker’s (unpublished) account of realization as one that, in virtue of Shoemaker’s causal account of properties, can explicitly incorporate the proper subset condition.