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Abstract
Melnyk provides a rigorous analysis of the notion of realization with the aim of defining Physicalism. It is argued here that contrary to Melnyk's Realization Physicalism, the idea that mental phenomena are realized by physical phenomena fails to capture the physicalist belief that the former obtain in virtue of the latter. The conclusion is not that Physicalism is false, but that its truth is best explained with some notion other than realization in Melnyk's sense. I also argue that the problems with Melnyk's brand of Realization Physicalism generalize to other potential attempts to express Physicalism in terms of realization. The burden of proof is on the Realization Physicalist to show that physicalist intuitions can be adequately captured with the notion of realization.
Notes
Robert Francescotti is Professor of Philosophy at San Diego State University.
Notes
[1] In this paper, I speak of mental rather than psychological properties simply because I wish to include the features of “folk psychology,” assuming these exist, while remaining neutral on the issue of whether folk psychological concepts should figure in the science of psychology.
[2] In section 2, two reasons are noted for not viewing both the realizer and the realized as tokens; one of these reasons is given by Polger and Shapiro (Citation2008).
[3] What follows ‘[R]’ are Melynk's exact words, although he uses the label ‘[RP-R],’ where ‘RP’ abbreviates ‘Realization Physicalism’.
[4] One might think that a mental event is not identical with the constituent neural event for the same reason one might believe that a statue is not identical with the constituent lump of clay—namely, the mental episode (statue) has different persistence conditions than the neural event (lump of clay). For example, an item can continue to be the same neural event (lump of clay) while ceasing to be a mental episode (statue).
[5] For an earlier and underdeveloped attempt to show that the mental can realize the physical, see Francescotti's (Citation2002), prior to Melnyk's (Citation2003, Citation2006) elaborate account of Realization Physicalism.
[6] According to Melnyk, a type is physical “iff either it is expressed by some positive predicate (e.g., ‘is an electron’, ‘has charge’) used in the formulation of the theories of current physics or it is expressed by some predicate constructable out of the positive predicates of current physics via the use of such predicate-forming machinery as the language of physics already contains, as well as of (possibly infinitary) conjunction and disjunction, and negation, so long as (i) the constructed predicate does not express a necessary property (e.g., that of either being a quark or not being a quark) and (ii) the constructed predicate is not entirely negative” (2003, p. 18).
[7] The non-physical realizing the physical is not only found in the case of mentality. If mental phenomena can realize the stuff of physics, then it should be no surprise that chemical and biological phenomena can do so as well. Consider, for example, a token x of the biological type, tendon, and suppose that x instantiates in manner P at the level of physics. In this case, x is of a biological type that meets the condition, C, of being instantiated in manner P, and meeting this condition necessitates that there is a token of P. So according to [R], biological tendon-token x realizes a token of a physical type. However, showing problems for Realization Physicalism with respect to all properties outside the domain of physics is too ambitious a project for a single paper. So the goal here is only to show problems for Realization Physicalism where mental properties are concerned.
[8] Shoemaker also requires that “X is not a conjunctive property having Y as a conjunct” (2001, p. 78). Without this constraint, realization would be too easy to come by. For any property F and any other property G, the conjunction F & G would realize both F and G. However, Shoemaker later comes to realize that a total ban on conjunctive properties as realizers is too strict (see his Citation2007, pp. 26–28).
[9] Shoemaker also expresses his subset view of realization with the notion of a forward-looking and a backward-looking causal feature: “one property realizes another if the set of its forward-looking causal features contains as a subset the forward-looking causal features of the other, and the set of its backward-looking causal features is a subset of the backward-looking causal features of the other” (Citation2003, p. 3).
[10] A major goal of Yablo and Shoemaker in presenting their accounts of realization is to solve the exclusion problem introduced by Kim (e.g., Citation1989, section V), the worry that if mental properties are not reducible to physical properties, then any mental property is excluded from being a cause by the underlying physical property. “The subset account,” Shoemaker notes, “obviously avoids the threat that the causal role of the realized property will be preempted by its realizers” (Citation2007, p. 13). For on this account, we do not have to view mental property M as vying with physical property P as the cause of, say, behavior B; rather the causal powers bestowed by M are included among those bestowed by P. And regarding Yablo's account: “determinates do not contend with their determinables for causal influence” (1992, p. 259) since the determinable simply abstracts away causally irrelevant detail and therefore contains just that part of the determinate that is sufficient for the effect.
[11] Endicott (Citation2006) cites Yablo's account and Shoemaker's as examples of what he calls the “metaphysical” tradition to understanding realization. Endicott mentions two other traditions. What he labels the “logic-semantic” tradition views realization as an interpretation of symbolic objects. Applied to mental properties, the position is that “a set of mental properties that constitutes a system's cognitive program is realized by a set of engineering properties possessed by that system if and only if (a) the system's behavior supports an interpretation according to which instances of the computational properties are internal symbols involved in the operations of the system, and (b) it is rational for the system to possess those symbols and operations under the stated interpretation” (Endicott, Citation2006, p. 428). Here, too, we have a version of the core functional approach, where the functional role is matter of satisfying some interpretation. What Endicott calls the “mathematical” tradition equates realization with a form of mapping between objects. In general, x realizes y because elements of y map onto the elements of x. However, the mere existence of a mapping, Endicott notes, does not distinguish between simulated and genuine realization. To guarantee genuine realization, Endicott suggests that one cite facts about causal structure, which gives the view that “a set of mental properties that constitute the cognitive program of a system is realized by a set of engineering properties possessed by that system if and only if (a) there is a one-to-one mapping between instances of the two sets of properties, and (b) the engineering included has the causal structure to satisfy the computational state transitions required by the program” (2006, p. 428). With the addition of (b), the mathematical approach also fits CFM.
[12] On another formulation, “P determines Q … only if (i) necessarily, for all x, if x has P then x has Q; and (ii) possibly, for some x, x has Q but lacks P” (Yablo, Citation1992, p. 252). For the example to fit this description, we can think of the properties P instantiated in M1 , P instantiated in M2 , … and P instantiated in Mn , each of which is sufficient for being P.