A Mereological Characterization of Physicalism

Abstract

Physicalism is usually understood as the claim that every empirical entity is or is determined by physical entities. The claim is however imprecise until it is clarified what are the physical entities in question. A sceptical argument in the form of a dilemma tries to show that this problem of formulation of physicalism cannot be adequately met. If we understand physical entities as the entities introduced by current physics, the resulting claim becomes most probably false. If we instead understand physical entities as those entities introduced by some future ideal physics, the claim then becomes indeterminate in content. Both horns seem equally bad. In the first part of the paper, I survey the strengths and weaknesses of different proposed solutions to this problem of formulation. In the second part, I lay out a new formulation of physicalism, partly based on a mereological principle, which overcomes the dilemma, and argue that it is a correct formulation of physicalism to the extent that it rules out clear antiphysicalist scenarios and is compatible with clear physicalist scenarios.

Acknowledgements

Research leading to this work has been partially funded by the Spanish Ministry of Education, research projects HUM 2004–05609–C02–02 and HUM 2005–04369. Also, this work, as part of the European Science Foundation EUROCORES Programme OMLL, was supported by funds from the DGI of the Spanish Ministry of Education, research project BFF2002–10164, and the EC Sixth Framework Programme under Contract no. ERAS‐CT‐2003–980409. A distant predecessor of this paper was presented at the III ECAP Conference held in Maribor and at the IX ESPP Conference held in Warwick. A more recent one was discussed in the LOGOS Seminar held in Barcelona. I thank all audiences there for helpful comments and suggestions. I am also extremely grateful to two anonymous referees of International Studies in the Philosophy of Science for useful comments and criticisms on a preliminary draft.

Notes

[1] Terminological note: throughout this paper, I will use ‘entity’ as a convenient dummy for an item of any ontological category, whether object, property, event, or process. Later on, I will dub entities belonging to the ontological categories of objects, events, and processes—that is to say, entities for which one can can sensibly ask whether they have proper parts—‘individuals’. So, according to this usage, individuals and properties will exhaust all entities.

[2] See Crane and Mellor (1990), as an instance of a work critical of physicalism where this rough formulation is endorsed, and Poland (1994), as an instance of a work defending physicalism where a formulation close to (P) is proposed. Details of Poland’s formulation, however, will be discussed below.

[3] Notice that under the intended reading of ‘physical entities’, claim (P) would read as: ‘every empirical entity is or is fully determined by those empirical entities which fully determine all empirical entities’.

[4] By ‘metaphysical priority of the entities studied by physics’, I just mean here that these entities belong to the basis of the relation of full determination discussed above.

[5] The dilemma is called ‘Hempel’s dilemma’ in Melnyk (1997), on account of the fact that Hempel was one of the first to formulate it. This dilemma is also one of the main arguments against physicalism in Crane and Mellor (1990). On the other hand, it is important to keep in mind that the dilemma arises only when one tries to restrict the class of physical entities by resorting to the theories of physics.

[6] In the next two sections, I will qualify this claim.

[7] See, for this criticism, Montero (1999) and Crook and Gillett (2001).

[8] A competent use of a theoretical concept need not require a deep understanding of the theory which introduces it; instead, merely being able to engage in an appropriate deferential practice might be enough. So, I am not claiming that only competent physicists can hold theses (PM) or (PH).

[9] I will go back to this objection later on, after having introduced my mereological caracterization of physicalism.

[10] It is fair to say that Melnyk does take into consideration the accessibility problem faced by his characterization of physicalism (Melnyk 1997, footnote 21). However, the remedy that he proposes is not satisfactory. Melnyk proposes to unpack his definition as the conjunction of two theses: (1) there is some science S, distinct from the totality of all the sciences, such that every entity (property) is either itself mentioned as such in the laws and theories of S or ultimately constituted (realized) by entities (properties) mentioned as such in the laws and theories of S; and (2) S is current physics. Melnyk then proposes that the common core of phyisicalism is allegiance to claim (1). Now, suppose again that current physics evolves in a set of theories according to which among the fundamental entities introduced by these theories there are mental entities. This possibility would not contradict Melnyk’s claim (1) but it would be overtly incompatible with physicalism.

[11] I have changed some of the original terminology used by Crook and Gillett for expository convenience. I will also ignore some of the details of their account which I judge to be of no consequence for the discussion to follow. For a full statement of Crook and Gillett’s characterization of physicalism, see Crook and Gillett (2001), Section 3.

[12] Bear in mind here that I use ‘entity’ for an item of any ontological category. See note 1.

[13] So, I understand biological emergentism as the claim that some biological properties including that of being alive are ‘weak emergent’ (Bedau 1997); thus, I think that a good characterization of physicalism should disallow weak emergence. Sometimes, vitalism is understood as a doctrine that amounts to what I call ‘biological emergentism’ in the main text. The distinction between vitalism and biological emergentism, however, can be traced back to the classical discussion in Broad (1925). In fact, Broad presented himself as a non‐vitalist who defended biological emergentism. On this aspect of Broad’s views, see Newman (2001).

[14] Recall that what is at stake is not whether biological emergentism is likely or not given the empirical evidence that we now have. What matters instead is whether the proposed definition of physicalism rules out situations in which physicalism would turn out false, regardless of the probability that these possibilities are real.

[15] Actually, I think this claim is too strong for the physicalist, for reasons that will emerge in the discussion of the next difficulty with Crook and Gillett’s proposal. The reader should view this bold claim as a rough and ready way of describing the physicalist position that needs some refinement. I shall make clear the refinements needed in the remainder of this section and in the next. Also, bear in mind that, as stated in Section 1, the relation of full determination entails the requirement of complete explanation.

[16] Here, I rely on the assumption that physical_MAT entities are introduced by description and on Russell’s theory of descriptions. If these assumptions were not shared, claim (PC&G) would still not be true on the possibility under consideration. That is all that this third objection requires.

[17] Unless, in such a world, mental entities are fully determined by further mental entities without end. I will comment on this possibility later on, when formulating my mereological characterization of physicalism. In any case, there are clearly worlds with no ultimate level of empirical entities which are clearly physicalistic worlds, and this is enough to show that proposal (C&G) is not correct.

[18] It might be objected that the idea of the unity of sciences was alien to at least some past materialists. I think that this is at least disputable. For one thing, past materialists thought that because of the truth of physicalism, there is in principle no unclosable gap between human sciences on the one hand and natural sciences on the other. For another, past materialists also thought that the entities which are the subject of what we now call ‘special sciences’ were also dependent on further empirical entities. In any event, I do not claim, as will be clear in a moment, that the thesis of physicalism contains a claim about the unity of science, only that it involves a claim that, under the characteristic way in which empirical sciences are individuated in our times, does entail a claim about the unity of these sciences.

[19] This proposal is far from original. The idea of linking the possibility of the unity of sciences to a mereologically stratified world can already be found in Oppenheim and Putnam (1958), although I disagree with their reductivist account of the unity of sciences.

[20] If we assume that material objects are continuants, that is to say, that they do not have temporal parts and that at any time at which they exist, they are present as a whole, and not just in part, then the relation of being a proper part of should be understood as relative to times for them. I am ignoring this complication here, since it depends on controversial ontological issues such as the cogency of the distinction between occurrents and continuants. In any event, taking this into consideration would lead us to formulate claim (1) in a more careful and complicate way, but the complication would not affect the point of the mereological characterization of physicalism.

[21] This is not an uncommon assumption in recent discussions of physicalism. See, for instance, Kim (1998, 2005).

[22] For instance, sometimes it is argued that an extensional principle should also be added to the effect that there cannot be two distinct individuals with exactly the same proper parts or alternatively that for any two overlapping individuals —that is to say, with proper parts in common— they have a maximal common part. However, extensional mereology is not beyond dispute, and therefore I do not find it wise to require of a physicalist a commitment to extensional mereology. For a thorough discussion of extensional mereology, see Simons (1987).

[23] Notice, however, that it is consistent with (1) that there are mental or biological properties at the lowest level in the hierarchy fully determining the rest of properties. I am assuming that this is not a genuine emergentist possibility, since, as commonly understood, emergentism involves the claim that mental or biological properties (or macrophysical properties) actually emerge at some level in an unexpected and unexplainable way. In any event, if one wants to count this possibility as a genuine emergentist position, then it is ruled out by the conjunction of claims (1) and (2) as made clear below.

[24] I am grateful to an anonymous referee of ISPS for calling my attention to this point and suggesting the necessity of the second conjunct of claim (2).

[25] Of course I am assuming here that one can grasp a concept without knowing explicitly an analysis of its necessary and sufficient conditions of application. It would be foolish to require a physicalist to have such an explicit analysis of mereological relations. In fact, I shall be content to assume that one can master a concept even if no such analysis in terms of necessary and sufficient conditions of application is possible.

[26] A troublesome possibility still remains. Imagine that future psychology evolves in such a way that it introduces a theoretical individual which is found to be ultimate. Is this compatible with physicalism or not? I think two cases need to be discerned here. First, suppose that this individual has folk psychological properties, for instance, suppose that it is conscious. In such a case, physicalism would be false, but the mereological characterization would be false, too, since (2) would turn out false because a folk special science entity, the property of being conscious, would belong to the ultimate level. Second, if that individual instead had no folk psychological properties, then in this second case the mereological characterization would be true. However, I do not see any compelling reason to deny that physicalism would also be true in that case. I think that even if such an entity were introduced in the exercise of a special science like psychology, it would probably be treated as a microphysical entity and assimilated to microphysics. In any event, I think this second case is not a very clear case from a physicalist standpoint. Therefore, I would say that the proposed characterizations of physicalism should not be assessed by taking a case as dubious as this into account.

[27] For a defence of claims of this sort, see Crane and Mellor (1990).

[28] Still, Jeffrey Poland seems to recommend such a view in passages like this:

although current [physical] theory provides the best estimate of what is in the domain of physics and thus in the bases, it neither provides the content of physicalist theses nor determines their fate. Therefore, given that some physical theory must be true if there are to be determinate physical bases and true physicalist theses, that theory need not ever be accessible to humans in order for the theses to be non‐vacuous. (Poland 1994, 166)

In spite of passages like this, Poland’s overall position with respect to Hempel’s dilemma is not entirely clear to me.

[29] Notice that Crook and Gillett’s proposal also incorporates a negative claim, since they require physical_MAT entities, among other things, to be non‐mental.

[30] By ‘metaphysical priority’, I just mean here full determination.

Additional information

Notes on contributors

David Pineda

David Pineda is at the Departament de Filologia i Filosofia, Universitat de Girona, Spain.