It’s A Duck… No, A Rabbit… No, It’s Physicalism!

I often argue that physicalism is false, but this is because I assume a reductionistic picture of physicalism based upon our current understanding of the physical universe.  I do not think that our current physical sciences can justify non-reductive physicalism with its exotic supervienences, panpsychisms, etc.  But I should put it this way, either physicalism is reductive and false, or non-reductive and trivial.  I say that non-reductive physicalism is trivial because it simply a priori defines any existing phenomenon as physical so as to preempt the discovery of some future phenomenon that lies outside of our current understanding of physical reality.  Essentially, I endorse Hempel’s dilemma on this point.  Daniel Stoljar (2009) writes the following of the dilemma:

One might object that any formulation of physicalism which utilizes the theory-based conception will be either trivial or false. Carl Hempel (cf. Hempel 1970, see also Crane and Mellor 1990) provided a classic formulation of this problem: if physicalism is defined via reference to contemporary physics, then it is false — after all, who thinks that contemporary physics is complete? — but if physicalism is defined via reference to a future or ideal physics, then it is trivial — after all, who can predict what a future physics contains? Perhaps, for example, it contains even mental items. The conclusion of the dilemma is that one has no clear concept of a physical property, no concept that is clear enough to do the job that philosophers of mind want the physical to play.

One response to this objection is to take its first horn, and insist that, at least in certain respects contemporary physics really is complete or else that it is rational to believe that it is (cf. Smart 1978, Lewis 1994 and Melnyk 1997, 2003). But while there is something right about this, there is also something wrong about it. What is right about it is that there is a sense in which it is rational to believe that physics is complete. After all, isn’t it rational to believe that the most current science is true? But even so — and here is what is wrong about the suggestion — it is still mistaken to define physicalism with respect to the physics that happens to be true in this world. The reason is that whether a physical theory is true or not is a function of the contingent facts; but whether a property is physical or not is not a function of the contingent facts. For example, consider medieval impetus physics. Medieval impetus physics is false (though of course it might not have been) and thus it is irrational to suppose it true. Nevertheless, the property of having impetus — the central property that objects have according to impetus physics — is a physical property, and a counterfactual world completely described by impetus physics would be a world in which physicalism is true. But it is hard to see how any of this could be right if physicalism were defined by reference to the physics that we have now or by the physics that happens to be true in our world.

A different response to Hempel’s dilemma is that what it shows, if it shows anything, is that a particular proposal about how to define a physical property — namely, via reference to physics at a particular stage of its development — is mistaken. But from this one can hardly conclude that we have no clear understanding of the concept at all. As we have seen, we have many concepts that we don’t know how to analyze. So the mere fact — if indeed it is a fact — that a certain style of analysis of the notion of the physical fails does not mean that there is no notion of the physical at all, still less that we don’t understand the notion.

One might object that, while these remarks are perfectly true, they nevertheless don’t speak to something that is right about Hempel’s dilemma, namely that for the theory-conception to be complete one needs to say a little more about what physical theory is. Here, however, we can appeal to the fact that we have a number of paradigms of what a physical theory is: common sense physical theory, medieval impetus physics, Cartesian contact mechanics, Newtonian physics, and modern quantum physics. While it seems unlikely that there is any one factor that unifies this class of theories, it does not seem unreasonable that there is a cluster of factors — a common or overlapping set of theoretical constructs, for example, or a shared methodology. In short, we might say that the notion of a physical theory is a Wittgensteinian family resemblance concept, and this should be enough to answer the question of how to understand physical theory.1

While Wittgensteinian family resemblances might be the best we can do to “define” physical theory, it is still inadequate to answer the charge of this dilemma.  The point is that we cannot anticipate what future member of this family might come about, so we cannot be sure what ought to count as physical.  Furthermore, it is precisely with regard to the boundary cases, the mind, and what is now called the supernatural, that may alter an change what is “defined” as natural or physical.  We must operate within the family resemblances we now have, not an ideal set of family resemblances.  Thus, I do not think Wittgenstein provides an out for this dilemma.  So I am content to say that physicalism is either false or trivial.
1D. Stoljar. 2009. Physicalism. The Stanford Encyclopedia of Philosophy. Retrieved September 4, 2011.

Posted on September 4, 2011, in Philosophy of Mind and tagged , , . Bookmark the permalink. 4 Comments.

  1. Hello Daniel!

    I just found this blog, and I must say I’m excited to dig through the archives once I have a moment. I found myself contemplating Hempel’s dilemma not too long ago after reading a post on cl’s blog.

    You said the force of Hempel’s dilemma rests upon the idea that we “can’t anticipate future members” of the physicalist family. This seems like a rather bizarre task to ask of a physicalist: how might we anticipate future physical members other than Wittgenstein family relations? Were we to suppose, before the advent of quantum mechanics, that quarks existed?

    Perhaps you could expound upon what you would expect of a physicalist in “anticipating future members”.

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  2. Matt,

    I have seen you on various blogs and am pleased you have found your way here. My blog is still fairly new, and sadly rough, but I hope you find some of the content of interest and worthy of your comments.

    You ask a very interesting question here and I suppose it cuts right to my point. I do not expect physicalists to be prognosticators at all. Rather, I recommend against making any such universal ontological statements in the first place. I suppose I am mostly chastising the strong physicalist who says that only physical/material things exist. The weak physicalist might say that it is only physical things in which she has found justification for belief. But a weak physicalist might still be open to the possibility that there are more things in Heaven and Earth than are dreamt in her philosophies. Still, there are problems even with this weak variety.

    Nonetheless, I can hardly fault someone for finding justification only for physical things. If that is all one finds justification for, then that is all they can say they know. In this sense, the weak physicalist is only being honest. Still, I think there are good arguments to justify the existence of non-physical entities. Those arguments must be made and the case must be put forward–a task from which I hope not to shy.

    I do fault the strong physicalist who is so hasty as to stipulate that all existing things are physical things. I take this to be an a priori position whereby the definition of physicalism is a mere triviality. And yet both the weak and strong physicalist have the serious burden of distilling a clear idea of what constitutes and defines physical reality–the key through which all known entities can be inferred to be physical and in no way non-physical. Thus, I think even the “weak physicalist” is susceptible to Hempel’s first horn. That is, the “weak physicalist” must admit that her justifications are limited and are likely to be overthrown by future revolutionary discoveries in physics. As Quine has said, no belief is immune from revision.

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  3. “And yet both the weak and strong physicalist have the serious burden of distilling a clear idea of what constitutes and defines physical reality–the key through which all known entities can be inferred to be physical and in no way non-physical.”

    As Stoljar mentions in his article, I think the lack of a concise definition of physical does not prevent us from being able to determine a clear conception of what a physical system is. While physics is likely far from completion (if it’s even possible), we can infer a family-resemblance concept in order to make future theories about the physical defeasible.

    This is an interesting task and one that I might take up soon, attempting to determine what family-relations we might confer between these various physical theories.

    It also seems pertinent that if non-physicalists wish to differentiate between physical and non-physical phenomena, that they too ought to have some idea of the principle differences between the two phenomena that would cause a change in category.

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  4. Matt,

    As Stoljar mentions in his article, I think the lack of a concise definition of physical does not prevent us from being able to determine a clear conception of what a physical system is. While physics is likely far from completion (if it’s even possible), we can infer a family-resemblance concept in order to make future theories about the physical defeasible.

    I think the issue is that the non-physicalist does not dispute the physicality of entities currently understood by our physics. We can say that certain incomplete physical systems give us a good idea of what physically exists, but this is inadequate when making the universal claim that all existing entities and phenomena are physical in nature. The non-physicalist points to various entities and phenomena and says that the current physics is inadequate. When the physicalist replies that some future or idealized physics will account for such things, or must account for such things, it comes off as a mere stipulation, i.e. by definition if it exists, then it will be accounted for by an ideal physics. At the same time, there is good reason to doubt that there ever will be a complete and consistent set of physical laws, as you hint with your “if it’s even possible” aside.

    If physicalism is based solely on our current understanding of physics, then I think there is good reason to think it is false. It cannot, as far as I can tell, adequately account for the individuation and identity of organisms, qualia, the status of propositions, numbers, moral and aesthetic values, and, if one takes cosmological arguments seriously, the existence of a non-physical cause of the universe. Now I know that there are many rebuttals to qualia, and the cosmological argument, though I remain unconvinced. One could be a subjectivist with regard to moral and aesthetic values and still manage in this world (though I think this is also misguided). One could deny the existence of numbers and propositions without too much difficulty. But, I do not think it is so easy for the physicalist to explain how persons are individuated without appeal to the idealized physics that we don’t have and might never have. The physics we do have seem to make it more and more implausible that identity and individuation will be explained. And this is why you might see me argue this point across various blogs and here. I think it is the most powerful objection to physicalism. In fact, on two separate occasions when I have made this argument against the physicalist, I was directed to the same wiki page: (http://en.wikipedia.org/wiki/Identical_particles). The physicalists with whom I have argued seem to think they are helping their cause when they argue that even the fundamental particles lack criteria for individuation and identity. One wonders where the emergent property of identity and individuation comes from. Perhaps it “supervenes” on organisms, whatever that might mean! Then again, maybe I do not have an adequate understanding of “supervenience”, I take it as the black-box of non-reductive physicalism by which many classic problems of reductionism are magically dissolved without the need to do one scientific experiement.

    It also seems pertinent that if non-physicalists wish to differentiate between physical and non-physical phenomena, that they too ought to have some idea of the principle differences between the two phenomena that would cause a change in category.

    A sound point indeed. What is sauce for the goose… But we might just embrace Hempel’s dilemma too. That is, if physicalism is defined by our current science, then non-physicalism is true. If physicalism is defined by some idealized physics that accounts for all existing entities, then non-physicalism is false, but only because it has been stipulated so (a rather uninteresting defeat of non-physicalism).

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