Online research in philosophy

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.

Multiple realizability has been at the heart of debates about whether the mind reduces to the brain, or whether the items of a special science reduce to the items of a physical science. I analyze the two central notions implied by the concept of multiple realizability: "multiplicity," otherwise known as property variability, and "realizability." Beginning with the latter, I distinguish three broad conceptual traditions. The Mathematical Tradition equates realization with a form of mapping between objects. Generally speaking, x realizes (or is the realization of) y because elements of y map onto elements of x. The Logico-Semantic Tradition translates realization into a kind of intentional or semantic notion. Generally speaking, x realizes (or is the realization of) a term or concept y because x can be interpreted to meet the conditions for satisfying y. The Metaphysical Tradition views realization as a species of determination between objects. Generally speaking, x realizes (or is the realization of) y because x brings about or determines y. I then turn to the subject of property variability and define it in a formal way. I then conclude by discussing some debates over property identity and scientific theory reduction where the resulting notion of multiple realizability has played a central role, for example, whether the nonreductive consequences of multiple realizability can be circumvented by scientific theories framed in terms of narrow domain-specific properties, or wide disjunctive properties.

Carl Gillett has defended what he calls the “dimensioned” view of the realization relation, which he contrasts with the traditional “flat” view of realization (2003, 2007; see also Gillett 2002). Intuitively, the dimensioned approach characterizes realization in terms of composition whereas the flat approach views realization in terms of occupiers of functional roles. Elsewhere we have argued that the general view of realization and multiple realization that Gillett advances is not able to discharge the theoretical duties of those relations (Shapiro 2004, unpublished manuscript; Polger 2004, 2007, forthcoming). Here we focus on an internal objection to Gillett’s account and then raise some broader reasons to reject it.

Carl Gillett has defended what he calls the “dimensioned” view of the realization relation, which he contrasts with the traditional “flat” view of realization (2003, 2007; see also Gillett 2002). Intuitively, the dimensioned approach characterizes realization in terms of composition whereas the flat approach views realization in terms of occupiers of functional roles. Elsewhere we have argued that the general view of realization and multiple realization that Gillett advances is not able to discharge the theoretical duties of those relations (Shapiro 2004, unpublished manuscript; Polger 2004, 2007, forthcoming). Here we focus on an internal objection to Gillett’s account and then raise some broader reasons to reject it.

Thomas Polger and Laurence Shapiro argue that Carl Gillett's much publicized dimensioned theory of realization is incoherent, being subject to a reductio. Their argument turns on the fact that Gillett's definition of realization makes property instances the exclusive relata of the realization relation, while his belief in multiple realization implies its denial, namely, that properties are the relata of the realization relation on occasions of multiple realization. Others like Sydney Shoemaker have also expressed their view of realization in terms of property instances, yet they too have accepted the multiple realizability of properties. Thus I am interested in the more general issue raised by Polger and Shapiro's argument. Specifically, I show how to supplement a theory of realization with a category-inclusive auxiliary assumption, which avoids the stated reductio. I then offer a few reasons to justify the proposed category-inclusive view of realization, making some comparisons to supervenience and causation along the way.

My topic is the confluence of two recently active philosophical research programs. One research program concerns the metaphysics of realization. Within the literature on realization there is substantial disagreement about even the general outlines of a theory. Occasionally it seems that the only common ground is that realization is a dependence relation that sometimes or always relates entities that figure in different explanatory schema, such as those of the special sciences and those of more fundamental sciences. The other research program concerns scientific explanation in terms of mechanisms. According to the advocates of the “new mechanism” there is a distinctive and important kind of scientific explanation that is generated by discovering and describing causal mechanisms. There is some dispute about whether this kind of explanation is genuinely distinctive. And there is much dispute about how exactly to characterize mechanisms. But even most critics of the new mechanism do not wish to replace it with old fashioned deductive-nomological explanation.

The by now famous exclusion problem for mental causation admits only one possible solution, as far as I can see, namely: that mental and physical properties are linked by a vertical relation. In this paper, starting from what I take to be sensible premises about properties, I will be visiting some general relations between them, in order to see whether, first, it is true that some vertical relation, other than identity, makes different sorts of causation compatible and second, whether physical and mental properties can be pairs of such relation.

According to the received view in philosophy of mind, mental states or properties are _realized_ by brain states or properties but are not identical to them. This view is often called _realization_ _physicalism_. Carl Gillett has recently defended a detailed formulation of the realization relation. However, Gillett’s formulation cannot be the relation that realization physicalists have in mind. I argue that Gillett’s “dimensioned” view of realization fails to apply to a textbook case of realization. I also argue Gillett counts as realization some cases that should not count if realization physicalism is to be distinguished from its competitors in the usual ways. I conclude that the relation described by Gillett cannot be realization.

The ?Dimensioned? view analyzes (multiple) realization in terms of compositional relation, and the ?Flat? view analyzes (multiple) realization in terms of causal-functional mechanism. The two different analyses of realization lead to the disagreement about whether realization is transitive. The two views, perhaps not surprisingly, have different consequences on testing for multiple realization, and prescribe different ?reconstructions? for the evidential significance of observation for multiple realization. I examine the differences between the two views on testing for multiple realization within a model-selection theoretical framework. I claim that the model-selection theoretical framework provides a ground to discuss and assess evidence for multiple realization.

How can mental properties bring about physical effects, as they seem to do, given that the physical realizers of the mental goings-on are already sufficient to cause these effects? This question gives rise to the problem of mental causation (MC) and its associated threats of causal overdetermination, mental causal exclusion, and mental causal irrelevance. Some (e.g., Cynthia and Graham Macdonald, and Stephen Yablo) have suggested that understanding mental-physical realization in terms of the determinable/determinate relation (henceforth, 'determination') provides the key to solving the problem of MC: if mental properties are determinables of their physical realizers, then (since determinables and determinates are distinct, yet don't causally compete) all three threats may be avoided. Not everyone agrees that determination can do this good work, however. Some (e.g., Douglas Ehring, Eric Funkhauser, and Sven Walter) object that mental-physical realization can't be determination, since such realization lacks one or other characteristic feature of determination. I argue that on a proper understanding of the features of determination key to solving the problem of MC these arguments can be resisted.