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Why Physics Alone Cannot Define the ‘Physical’: Materialism, Metaphysics, and the Formulation of Physicalism

Published online by Cambridge University Press:  01 January 2020

Seth Crook  and
Carl Gillett
Seth Crook
Affiliation:
Illinois Wesleyan University, Bloomington, IL61702-2900, USA
Carl Gillett
Affiliation:
Illinois Wesleyan University, Bloomington, IL61702-2900, USA
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Extract

Materialist metaphysicians want to side with physics, but not to take sides within physics.

If we took literally the claim of a materialist that his position is simply belief in the claim that all is matter, as currently conceived, we would be faced with an insoluble mystery. For how would such a materialist know how to retrench when his favorite scientific hypotheses fail? How did the 18th century materialist know that gravity, or forces in general, were material? How did they know in the 19th century that the electromagnetic field was material, and persisted in this conviction after the aether had been sent packing?

The doctrine of physicalism casts a long shadow in contemporary philosophy, configuring all kinds of philosophical issues and projects. Unsurprisingly, its proponents argue that physicalism has all the obvious features necessary for a scientific hypothesis to be in what we will call ‘good standing,’ i.e. being worthy of serious scientific investigation. In fact, many claim much more, arguing that physicalism is a well-confirmed hypothesis and possibly amongst the best of our theories. But, as our second opening passage makes clear, a persistent worry has been that physicalism, or ‘materialism’ as van Fraassen terms it, is an edifice built on sand. For many philosophers question whether the ‘physical’ can be specified at all, or at least in a manner that will produce a physicalism that would be in good standing.

Type
Research Article
Information
Canadian Journal of Philosophy , Volume 31 , Issue 3 , September 2001 , pp. 333 - 359
Copyright
Copyright © The Authors 2001

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References

1 Lewis, David ‘New Work for a Theory of Universals,’ Australasian Journal of Philosophy 61 (1983) 343–77, at 364CrossRefGoogle Scholar

2 van Fraassen, Bas ‘Science, Materialism and the False Consciousness,’ in Kvanvig, J. ed., Warrant in Contemporary Epistemology: Essays in Honor of Plantinga's Theory of Knowledge (Lanham, MD: Rowman and Littlefield 1996), 169Google Scholar

3 For example, see Fodor, J. ‘A Theory of Content,’ in Fodor, J. A Theory of Content (Cambridge, MA: The MIT Press 1990)Google Scholar for an example of a naturalization project justified by reference to physicalism, and Kim, J. Mind in a Physical World: An Essay on the Mind-Body Problem and Mental Causation (Cambridge, MA: The MIT Press 1998)CrossRefGoogle Scholar where physicalism provides the background for his construal of the ‘problem of mental causation.’

4 For example, see Hempel, C. ‘Comments on Goodman's Ways of Worldmaking, Synthese 45 (1980) 193–200CrossRefGoogle Scholar, and ‘Reduction: Ontological and Linguistic Facets,’ in Morgenbesser, S. et al., eds., Philosophy, Science, and Method (New York: St. Martin's 1969)Google Scholar; Chomsky, N. Language and Mind (New York: Harcourt Brace and World 1968)Google Scholar, and Knowledge of Language (New York: Praeger 1986); and Crane, T. and Mellor, H. ‘No Question of Physicalism,’ Mind 99 (1990) 185–206CrossRefGoogle Scholar; as well as van Fraassen.

5 Melnyk, A. ‘How to Keep the “Physical” in Physicalism,’ Journal of Philosophy 94 (1997) 622–37CrossRefGoogle Scholar

6 Melnyk, A. ‘How to Keep the “Physical” in Physicalism’; and Poland, J. Physicalism (Oxford: Clarendon 1994)Google Scholar

7 Why are we ultimately concerned with the features necessary for a scientific hypothesis to be in good standing when we argue that physicalism is a philosophical hypothesis? Because we take the features underpinning Hempel's dilemma, such as being more likely than relevant rivals, or having the capacity to progress, and not being vague, or indeterminate, or a trivial doctrine, to be necessary features for any hypothesis to be in intellectual good standing, i.e. good standing simplicter!

9 For typical recent examples of a physicalism based upon realization see Melnyk, A. ‘Being a Physicalist: How and (More Importantly) Why,’ Philosophical Studies 74 (1994) 221–41CrossRefGoogle Scholar; and for one based upon a supervenience relation see Post, J. The Faces of Existence (Ithaca, NY: Cornell University Press 1987)Google Scholar.

10 For examples of recent physicalists who take this doctrine to concern more than just the logically contingent entities see Bigelow, J. The Reality of Numbers: A Physicalist's Philosophy of Mathematics (Oxford: Clarendon 1988)Google Scholar; and Maddy, P. ‘Physicalistic Platonism,’ in Irvine, D. ed., Physicalism in Mathematics (Dordrecht: Kluwer 1990)Google Scholar. We believe these exceptions prove the general rule.

11 Below all references to Melnyk are from ‘How to Keep’ unless otherwise indicated.

12 Although Melnyk does not mention it, we add the rider ‘all else being equal between Hand its rivals’ as a friendly amendment, since there is good evidence that scientific theory appraisal both involves the comparison of rivals and is multi-faceted, with many features being used in such comparisons.

13 Is P+ a relevant rival to physicalismCUR? Melnyk elucidates what he takes to be a relevant rival to a theory in the following manner:

(RR) A hypothesis H1 is a relevant rival to H2 if and only if (a) H1 is sensibly intended to achieve a significant number of H1's theoretical goals; (b) the hypotheses, H1 and H2, fail to supervene on one another; and (c) H1 has actually been formulated. (626)

It appears that P+ is a relevant rival to Melnyk's physicalism, since it satisfies the conditions laid down by Melnyk in (RR). First, P+ passes condition (a) of (RR) because it has just the theoretical goal Melnyk himself claims rivals must have in ‘giving an account of the relations among the ontologies that the many sciences … respectively postulate, in light of such cross-scientific regularities as have been discovered empirically’ (633). Second, P+ passes condition (b) demanding that the two theories do not supervene since the extra entity of P+ will be involved in further laws not found in current physics and hence PhysicalismCUR and P+ will not supervene in either their ontologies or laws. Third, condition (c) demands a hypothesis be formulated, and we have now formulated P+ (and we contend that other philosophers, such as Strawson, G. Mental Reality [Cambridge, MA: The MIT Press 1994]Google Scholar, have previously also given less formal accounts of P+). And apparently in sufficient detail, since we have not simply referred to some possible future theory, but instead given a definite account of the nature of the relevant theory's ontology. (Furthermore, we should note that such detail is apparently sufficient, since it at least equals, and most likely surpasses, the detail of dualistic or vitalistic hypotheses that are acknowledged by Melnyk as relevant rivals to physicalism).

14 At this point it may be objected that P+ relies upon an extension to current physics, So PhysicalismCUR might be represented as making the claim that there are A entities and P+ the claim that there are A and B entities. But, the objection continues, we know that some statement A is always more probable than the conjunction of this statement with some further claim. Thus, the objector concludes, we can quickly see that far from physicalismCUR being less probable than P+, the reverse is true. This claim about the relative probabilities of statements and their conjunctions may be true when the statements involved are taken in isolation, but our claim about the relative probabilities of physicalismCUR and P+ is not being made in isolation. Rather, we are arguing that when taken against the background of our knowledge of the history of the sciences, and physics in particular, then P+ is more likely than physicalismCUR· (Note also that all we strictly need establish to show that physicalismCUR fails Melnyk's own condition ADEQUACY is that P+ is equal in its likelihood).

15 Have we burdened Currentism with too strict a definition? It might be objected that a Currentist can defend a weaker, revised definition such as the following:

(CURRENTISM*) An entity is a basic physical entity, is ‘physicalCUR*,’ if and only if it is an entity directly referred to in the laws or theories of the designated portion of the current physics or is relevantly similar to one.

I. Ravenscroft, ‘Physical Properties,’ Southern Journal of Philosophy 35 (1997) 419-31, basically defends this position. We should note the close resemblance of this hypothesis to P+. The idea behind the suggestion would be to argue that under the new definition the as-yet-undiscovered entity to which P+ is committed would also be posited by physicalismCUR*, since this entity is relevantly similar to the entities of current physics. Thus P+ and physicalismCUR* would not be distinct and the objection to Currentism is defused since P+ is not a relevant rival.

Many will perhaps favor this response, but we believe it fails to save Currentism. First, we agree that P+ and physicalismCUR* are closely related, and we contend both are more likely to be true than Melnyk's physicalismCUR· Second, we suggest that the problem with such a revised definition is how to understand ‘relevant similarity’ to the entities of current physics in a manner that leaves physicalismCUR* as a version of Currentism. Would it, for example, exclude as basic physical entities any uncomposed mental entities posited in some interpretation of quantum mechanics? In answering such questions we contend that the revision must obviously go beyond Currentism by appealing in its understanding of ‘relevant similarity’ to some notion of the ‘physical’ wider than simply the posits of current physics. This can be done in either of two ways.

One might continue to look to the concepts of physics and appeal to a Futurist analysis using a future physics to supply the wider concept of the ‘physical.’ Or, more radically, one might move to a type of account that completely abandons direct reliance upon the concepts of physics in crafting such a notion of the ‘physical.’ In the former case, the suggestion abandons the guiding idea of Currentism in favor of its Futurist rival and we shall argue in Part II that such Futurist accounts also fail to overcome Hempel's dilemma. In the latter case, where direct reliance upon the concepts of physics is abandoned, then we suggest that one will be left with the kind of account we shall ultimately defend in Part III. Which of these options Ravenscroft favors, if either, we are unclear about, since he never clarifies what he means by ‘relevant similarity.’ However, either of the ways one may make such a clarification entails that the revision fails to sustain Currentism, and/or direct reliance upon the concepts of physics in successfully defining the ‘physical.’

16 Note that this second criticism of Currentism is based on the assumption that physicalismCUR is an incomplete hypothesis. Someone could try to defend Currentism by arguing that our present physics is complete. But we are skeptical about the chances of success of such a project. For given the historical evidence the likelihood of discovering new fundamental particles, etc., makes it prima facie plausible that we do not now have a completed physics.

17 All references are to Poland, Physicalism, unless otherwise noted. In 157-76, Poland deals with the objection that his account is indeterminate, and then in 142-7 outlines his initial response to Chomsky's triviality objection based on downward incorporation. A separate section of chapter 6, 329-33, entitled ‘The Problem of Downward Incorporation,’ then elaborates Poland's further responses to Chomsky. These passages support our view of Poland as a ‘Futurist.’ In addition, Poland never makes clear whether he favors the final, complete, or ideal science fitting his characterization of ‘physics’ and we will therefore bracket this question in our outline of his position. Nothing will turn upon this bracketing in our arguments.

18 Williams, D.C. ‘The Elements of Being,’ Review of Metaphysics 7 (1953) 3–18 & 171-92Google Scholar

19 We should note that our version of physicalism is a claim about the nature of the logically contingent entities that compose all other such entities, as befits a hypothesis in speculative cosmology. Thus when we talk of entities composing other entities we shall mean logically contingent entities, though for stylistic reasons we shall often leave this implicit.

20 Lakatos, I. Philosophical Papers, Vol. 1: The Methodology of Scientific Research Programmes (Cambridge: Cambridge University Press 1978)CrossRefGoogle Scholar

21 Once again, we include the ‘i.e.’ clause to mark that by ‘compose’ we still seek to be neutral amongst the various views about the ontological relation upon which physicalism should be built. Thus whenever we use ‘compose’ in outlining our positive account this should be taken to mean RN and is intended to remain neutral between realization, constitution, identity, supervenience, etc. Note also that the definition is intended to imply that the basic physical entities are the base relata of the relation RN.

22 Cornman, J. Materialism and Sensations (New Haven: Yale University Press 1971)Google Scholar; and Smith, A.D. ‘Non-Reductive Physicalism?’ in Robinson, H. ed., Objections to Physicalism (Oxford: Clarendon 1993)Google Scholar

23 Spurrett, D. and Papineau, D. ‘A Note on the Completeness of “Physics”,’ Analysis 59 (1999) 25–9CrossRefGoogle Scholar; and Montero, B. ‘The Body Problem,’ Nous 33 (1999) 183–200CrossRefGoogle Scholar

24 Furthermore, we should also note that Gillett, C. and Witmer, D.C. in ‘A “Physical” Need: Physicalism and the Via Negativa,’ Analysis 61 (2001) 302–9CrossRefGoogle Scholar, offer detailed arguments that the ‘non-mental’ fails to be an adequate philosophical replacement for the ‘physical.’

25 Note that one need not follow Williams in the manner in which he draws this distinction amongst entities. For rather than logical contingency and necessity, one might easily focus instead, for example, upon the properties of being capable or incapable of real change. The latter distinction, as well as a number of others, also serves to draw the intended division amongst entities.

26 We should note our account can still be used by those who want physicalism to be a theory addressing the relations amongst both logically necessary and contingent entities. If one simply deletes the references to ‘logically contingent entities’ in the definition of the ‘B-list,’ (I)-(III) and MATTER, then one would have formulated what we think is the most defensible physicalism of this kind.

27 Thanks to David Anderson for pressing the importance of this type of concern. A potentially important question is still whether a version of Hempel's dilemma arises with regard to the issue of specifying the ‘mental’? In response we should mark the important differences between (folk or scientific) psychology and physics. For these disciplines differ both in the scope of their goals, the maturity of their theories and hence the degree to which they undergo revisions. Given these points, we therefore do not yet see any analogue of such a dilemma in the case of the mental for the reasons outlined. Nonetheless we acknowledge the potential seriousness of this issue.

28 If one accepts Melnyk's point that physicalism need only be more likely than its rivals then one will accept that we are actually defending a stronger claim than we need in order to overcome Hempel's dilemma. Nonetheless, we believe our present evidence is such that it remains to be shown that physicalismMAT is even likely to be false.

29 We should note that our account also avoids another problem commonly argued to dog formulations of physicalism. For our account is not apparently open to a charge of vagueness or indeterminacy. As we argued above, given our present evidence, physicalismMAT makes determinate claims about the entities that are in the set that compose all other logically contingent entities, for example, leptons, quarks, and other entities of present physics. And our doctrine also makes determinate claims about the entities that are not in the set, for instance mental entities and biological entities such as pigs, amongst others.

30 The most famous contemporary defense of (b) is Field, H. ‘Tarski's Theory of Truth,’ Journal of Philosophy 69 (1972) 347–75CrossRefGoogle Scholar, but see also Field, H. ‘Physicalism,’ in Earman, J. ed., Inference, Explanation, and Other Frustrations (Berkeley, CA: University of California Press 1992)Google Scholar; Hellman, G. and Thompson, F. ‘Physicalism: Ontology, Determination, and Reduction,’ Journal of Philosophy 72 (1975) 551–62CrossRefGoogle Scholar; and J. Poland, Physicalism, amongst others.

31 Gillett, C. ‘The Methodological Role of Physicalism: A Minimal Skepticism,’ in Gillett, C. and Loewer, B. eds., Physicalism and Its Discontents (Cambridge: Cambridge University Press 2001)CrossRefGoogle Scholar

32 For example, the primary concern of Spurrett and Papineau is to frame so-called ‘Causal Arguments,’ the most famous being so-called ‘Arguments from the Completeness of Physics.’ We contend our definition of the basic physical entities clearly suffices for this, and other, metaphysical tasks. As we noted above, there may also be good reasons to be think that the Via Negativa approach of Spurrett and Papineau fails with such tasks. See Gillett and Witmer, ‘A “Physical” Need,’ for a detailed defense of the latter point.

33 We would like to thank the editors and two anonymous referees for helpful comments on an earlier version of the paper. For helpful discussion we would also like to thank David Anderson, Lenny Clapp, Paul Lodge, Liane Stillwell, and the audience at the joint Illinois Wesleyan University/Illinois State University philosophy colloquium where we read a version of the paper.