Must Physicalism Imply the Supervienence of the Mental on the Physical?

Presenter: Barbara Gail Montero, City University of New York

Commentator 1: Robert Howell, Southern Methodist University

Commentator 2: Gene Witmer, University of Florida

Commentator 3: Frank Jackson, Australia National University & Princeton University

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25 Comments

  1. Hi Barbara,
    I thought I might write to keep pushing a few points, though in the end we may not wind up too far apart.

    You suggest that if, as I suggest, there is a reason to count the chemical, biological, etc. as physical, we should focus on whether or not that reason applies to the mental, not on whether or not the mental supervenes on those things. I’m not sure I agree completely, but even if I did would this really defend your thesis? Wouldn’t it still be the case that there is a non-trivial supervenience thesis that is a necessary condition for physicalism?

    I do, as a matter of fact, think there is a shared nature among these things, but suppose one didn’t. One could still think it is an important question whether the mind bears a certain relationship to those other things out there. For example, the “reason to count the chemical” etc. as physical might simply be that we have successfully explained much of these things to our satisfaction, and we might wonder what the relationship of the mental to those things is. This reason doesn’t apply to the mental, and the supervenience question still seems a good one.

    I find myself wondering a little in this debate–are you really denying that supervenience of the mental on the narrow-physical base is a necessary condition for physicalism, or are you ultimately unsatisfied with characterizations of the base? The arguments sometimes sound like they support the latter. Or here’s another possible way to put your argument–given current ways of characterizing the base, supervenience on that base is not necessary for physicalism. Given a characterization of the base that makes supervenience necessary, make s it philosophically otiose since we should then merely ask whether that characterization applies to the mental. Would that be a fair statement of your view?

    More later. Cheers
    Robert

  2. Another brief note. I think that the Kripkean stuff in my response was not particularly well thought out, and it might be confused. I typically have the sense that Kripkean objections like this just change the way the initial view needs to be stated–that is that they are more semantic points than metaphysical ones–but I waver.
    In any case, you say “As long as you think both that there is some way that our physics could have been so that it does not suffice for, say, chemical bonding, and that if our physics were like this, physicalism still could hold, then it would seem that the mental could be physical, even if the mental does not supervene on the entities, properties, relation and laws of physics.”

    I guess I’m not sure there is a way that our physics could have been like that. There is a possible world where there is a discipline called physics which was much like ours and studied things much like ours, and in that world the stuff studies by that discipline would not be sufficient for chemical bonding. But I’m not sure what that says about our world. You might be right–and I certainly seem to see what you mean–but I do have some worry that when we twist a few of the world-knobs we can’t just assume the resulting description is really coherent and that it’s not only my ignorance of science that makes it seem so. So, forgetting Kripkean vocabulary, this is my worry here.
    Robert

  3. Oh well, while I’m here I might as well finish by talking about the last bit of my comments. I admit, it might not be too helpful by talking about “monism” when defining “physicalism” since it’s not totally clear what the former is. But I guess I do think that if there are really two different things–like matter and anti-matter–and they really can’t be described as sharing a nature, dualism of a sort would be true, and an important sort of physicalism would be false. I don’t think this is the case, though. I suggest briefly that I think our notion of the physical is grounded in the idea of things that can be described fully in terms of their impact on spatiotemporal dynamics. I think matter and anti-matter don’t seem likely counterexamples to this, at least from what I understand about them.
    You do mention a criticism of my view which I answer in a forthcoming book (which builds on my Physicalism, Old School article in part), namely that physicists “ponder the question of whether space-time itself is ultimately explained in terms of underlying non-spatiotemporal phenomena.”
    My answer to this is somewhat long, too long for here, largely because I think there are many things that might be meant by this hypothesis, and many of them are not really inconsistent with my view. For example, it might be that classical spacetime is emergent from an infinite dimensional Hilbert space, or something like that. If that is the case, the view is just about that Hilbert space. In other words, this view is not committed to a particular story of spacetime. Whatever the right way to describe it is, it seems that something like this view will work. If, however, it is meant that spacetime emerges from something that is so unspacetimelike that it cannot be handled in this way, there might be an issue (though I think a close plan B is in the offing). But I don’t see many physicists saying this. (Though admittedly my knowledge is quite limited.)
    One last thing. I really don’t think “physicists are pondering about x” can make x a counterexample, especially when the details are not in. Physicists might ponder a lot of things that make no sense in the end. In addition, given your commitment to the Hempelian Dilemma, I would think you would want to reserve the right to say that at some point physics has gone off the rails, at least with respect to what we care about as philosophers. I’m not sure we shouldn’t think it would have if it moves to a view that posits this more brute form of emergence. Hell, I’m not sure it hasn’t already with string theory. But I’ll be I’m in the minority.
    Cheers
    Robert

  4. Thank you Robert for the triage! Let me see what I can say rather briefly in response. You ask why a reason to count the chemical, biological, etc. as physical would not amount to some non-trivial supervenience thesis that is necessary for physicalism. My response is: why must it? Mightn’t there be some other reason, apart from a supervenience relation, to count, say, the biological as physical? I suggest one such reason in my response to Frank: such features of the world count as physical because they do not hint at the existence of God. Perhaps there are better reasons, but this shows, I think, that there is at least some sort of reason distinct from a supervenience relation.

    You wonder whether my point is that we do not have the correct supervenience base rather than that supervenience itself should not be thought of as a necessary condition for physicalism. I intend my argument against supervenience being a necessary condition for physicalism to apply to any base properties you choose (apart, of course, to the very broad “base” that includes everything).

    Could our physics not suffice for the chemical, biological etc.? I don’t know, but let’s say, as you put it, “there is a possible world where there is a discipline called physics which was much like ours and studied things much like ours, and in that world the stuff studied by that discipline would not be sufficient for chemical bonding.” If you take it that physicalism could still be true in this world, what this shows is that a supervenience thesis is not a necessary condition for physicalism. It might still hold in our world, but neither in that world nor in ours does physicalism entail it.

    Is there something more fundamental than space-time? It seems that if there is, it need not necessarily be nonphysical.

  5. Dear Robert and Barbara

    Barbara’s words above “I intend my argument against supervenience being a necessary condition for physicalism to apply to any base properties you choose” prompt me to add a small comment.
    Isn’t there an interesting question one can raise without entering the debate about what physicalism really is? It is a general question in metaphysics. Here’s the question. For some set of properties B instantiated at our world, is it or is it not the case that any minimal duplicate of our world with respect to B is a duplicate simpliciter? If B includes all properties instantiated at our world, the answer is trivial as Barbara in effect notes, but for (interesting) proper sub-sets of the properties instantiated at our world, it seems a good question to ask.

    Cheers

    Frank

  6. Frank, yes, I agree that that is a good question to ask. I just deny that the nagative answer to it implies that physicalism must be false. Moreover, in focusing exclusively on it in the debate over physicalism, we might be missing some other good questions.

  7. Barbara,

    My apologies for being so late in jumping in. But here I am now. Let me start ith your very first paragraph in response. You write:

    “Gene Witmer is shocked that I think we need an argument to show that physicalism must imply that mental properties cannot be over and above physical properties. I’m not surprised by this. Witmer, like most, just understands physicalism as entailing a supervenience thesis. I think it is worthwhile, however, to ask why it should, and I take the primary value of my paper as merely posing this question.”

    First, I should stress that I don’t simply understand what “physicalism” means in the first place by thinking of it as entailing a supervenience thesis. Rather, I think of it in the first place — that is, when I am simply trying to locate the idea as one to subject to clarification, prior to attempts at such clarification — as a claim about one sort of fact being somehow nothing over another, as being something that derives from another, that ‘reduces’ (in at least one appropriately metaphysical sense) to another, and so on. The point about supervenience is derived from this more basic core characterization. I don’t take it to be simply a terminological matter that physicalism implies an appropriate supervenience thesis. What *is* a terminological matter is that “physicalism” denotes a thesis that fits those preliminary characterizations (using “nothing over and above” and “reduce” talk and so on). If someone tells me that they didn’t understand the label to apply to a thesis that fit those characterizations, I suspect that at that point we are just talking past each other.

    Second — and most important — I am puzzled by your remark that your paper is meant merely to pose the question as to whether physicalism entails a supervenience thesis. Obviously, you don’t mean to say that you only want to pose the question; surely, you want to give reasons to think that, at a minimum, it’s not obvious that the answer is Yes, and more ambitiously, to give reasons to think that the answer is No.

    Now, you accept the idea that if physicalism is a “nothing over and above” (NOA for short) thesis of the sort I stress, then it indeed entails an appropriate supervenience thesis. So you must mean to cast doubt on the claim that physicalism is such an NOA thesis. So I fear you may just have something in mind quite different from what I take “physicalism” to be. However, on reflection, that seems to me quite unlikely. It seems more plausible that what is driving your discussion is primarily the contrast between different categories one might understand as the category of the physical and the resulting different requirements of physicalism.

    But let’s set that aside for a moment. If there *is* another core idea that you are focusing on, what is it? In my comments I spent time trying to find some indication of what alternative understanding of “physicalism” you think is available. But each such alternative understanding I could find hinted at in your paper seemed to turn out, on examination, to be quite inadequate.

    The closest you come to endorsing an alternate conception is what I formulated on your behalf as (3):

    (3) However the mental relates to the rest of the world, that relation is unexceptional; many other domains bear the same relation to the rest of the world.

    So here are some questions for you:

    Do you think (3) succeeds in picking out, however roughly, the intuitive content of physicalism?

    If not, then can you say anything about what physicalism is supposed to be that doesn’t involve an NOA thesis?

    If you do think (3) succeeds in picking out that intuitive content, how do you respond to the point that (3) is compatible with a kind of pluralist dualism that I described? If there are dozens of kinds of things in the world and none of them reduce to any other, is that consistent with physicalism? I would have thought that is just plainly incompatible with it. It’s just dualism of the traditional sort expanded to include many more irreducible kinds of things.

  8. Glad you’re here, Gene. (I suppose!) So, Gene, you think of physicalism, in the first place, not as entailing supervenience but rather as being a claim about one sort of fact not being over and above another sort of fact. OK, I don’t think it is about that either. You don’t believe that I really think that physicalism is not committed to the view that the mental is nothing over and about the narrowly physical (be this defined over physics, the physical sciences, or the nonmental.) But I really do think this. Are we just talking past each other? Can’t I try to convince you that you’ve somehow latched on to an incorrect way of understanding supervenience?

    I do try to do this in the paper, even though, and I’ll say it again, I take the primary value of my paper as merely posing the question of whether physicalism entails a supervenience thesis (or that it entails that the mental is nothing over and above the physical). This is not to say, as you seemed to understand me as saying, that my “paper is meant merely to pose the question as to whether physicalism entails a supervenience thesis.” I did indeed mean for it to do more, but the primary value, I imagine, is opening up a new topic of debate, in showing that there is a question to be asked (but it seems that I have not succeeded in convincing you of even this).

    So, given that I think that physicalism does not entail a supervenience thesis, what, as I see it, is the core idea of physicalism? True enough, I must have some reason for thinking that supervenience is not a necessary condition for physicalism, and this reason must have to do with what I see as the core idea of physicalism. Is the core idea your (3): “However the mental relates to the rest of the world, that relation is unexceptional; many other domains bear the same relation to the rest of the world”? Well, I’m not troubled by what you see an objection to this: it’s a kind of pluralism. I’ve never been good at counting the number of kinds of thinks there are in the world, but it seems that whatever total you arrive at, it doesn’t really matter relevant to physicalism. What’s wrong, for example, with there being two kinds of things in the world? I’ve never understood why that should strike people as physicalistically unacceptable. Of course, dualism was given the name dualism because (on some ways of counting things) it posits two kinds of things, but is this really what physicalistis should find abhorrent? Or is it something about how Descartes thinks of the mental? Moreover, if you are stuck on there being one kind of thing, (3) allows for this since if nothing is unexceptional, everything is physical, according to (3) and thus everything is of the same kind. (And, of course, everything can be of the same kind in infinitely many other ways as well. For example, if (3) is true, everything is the kind of thing that is self identical, or if you don’t like that and want a property that only contingently applies to everything, everything is such that it is either Ben Franklin or not the First Postmaster General). So this objection, does not bother me.

    However, I think that (3) is probably not entirely right for other reasons. As I said in my response to Jackson’s commentary, something like (3) could be true even if God exists and sets everything in motion yet, it is at least not clear that physicalism should be true in such a situation. So, as I suggested in my paper, I think the core physicalist idea has something to do with rejecting a world where God plays a managerial role as well as a world that evokes this idea, as it done when the mental is given a position of honor. After my talk at the Graduate center on this on Wednesday, Henry Shevlin suggested that perhaps physicalism is an anti-anthropomorphizing thesis. And I think that is a pretty good suggestion. But this is all very vague and I need to think much more about these issues.

  9. Barbara,

    It may be that we are talking past each other. What it seems to me is actually going on is a combination of two things. There are two distinct views, physicalism and naturalism, and your intuitions are partly being driven by naturalism as opposed to physicalism. But another thing going on is that you’re noticing the different ways of formulating physicalism, depending on what one takes as the physical base — the narrowly physical, the broadly physical, the non-mental, or whatnot. What Shevlin suggested to you is I think a good thought: I think what metaphysical naturalism amounts to is a kind of anti-anthropomorphism thesis. In brief, on my view, metaphysical naturalism is the claim that those things in the world that are of special interest to humans are not fundamentally different from those things that are not of any special interest to us. The formulation (3) I suggested is along these lines (though not exactly how I would set things up independently). But this seems to me quite distinct from physicalism, partly because, well, a simple pluralism with countless irreducibly different kinds of things is consistent with naturalism but not with physicalism. (I have a paper “Making Sense of Naturalism” in which I defend this way of thinking about metaphysical naturalism.)

    That’s what I think is going on overall, but to turn to details —

    So what might be the core idea of physicalism if not something with a “nothing over and above” clause? You don’t quite give an answer to this, saying that my suggested (3) is close, but not quite there. But what I want to focus on is your sense that a certain situation is consistent with physicalism — namely, the world I described earlier in which, as I said, all the distinguishable kinds of phenomena are metaphysically independent of each other, so that the chemical is something over and above the physical; the biological is over and above the chemical; the mental is over and above the biological; and so on.

    You think this situation is consistent with physicalism; I do not. You write:

    “Well, I’m not troubled by what you see an objection to this: it’s a kind of pluralism. I’ve never been good at counting the number of kinds of thinks there are in the world, but it seems that whatever total you arrive at, it doesn’t really matter relevant to physicalism. What’s wrong, for example, with there being two kinds of things in the world? I’ve never understood why that should strike people as physicalistically unacceptable. Of course, dualism was given the name dualism because (on some ways of counting things) it posits two kinds of things, but is this really what physicalists should find abhorrent?”

    Hold on. The issue isn’t whether there is something wrong with there being kinds of things in the world –or many kinds of things in the world. The issue is whether the situation is consistent with physicalism. If it is not, then, of course, the physicalist will hopefully have something to say about why such a situation is implausible. But he isn’t bound to saying that what makes it implausible is that it has more than one kind of thing in the world!

    What the physicalist finds implausible about such a world is that he thinks we have reason to think that everything in the world is fundamentally physical — and that, of course, implies a kind of anti-pluralism. But I am quite in sympathy with you when you say that you’ve “never been good at counting the number of kinds of things there are in the world.” I think that talk of number of kinds of just to court confusion. What matters is that there is already identified a privileged kind of thing — the physical. However, exactly, that is to be understood.

    Let me try another tack here. I think it is pretty safe to say that we’ll all agree that a physicalist is committed to either (4) or (5):

    (4) Everything is physical

    (5) Everything is _________ physical

    where the blank is filled in with some kind of qualifier, e.g. “ultimately” or “fundamentally” or such.

    Could either of those be true in the situation we’re talking about (where we have this general pluralism and many things that are not physical in any sense)? If not, isn’t that reason to reject that situation as incompatible with physicalism?

  10. here’s one reason to doubt that physicalism entails supervenience. in a purely physical world w, there might be two similar objects, A and B, that differ only in their location and their mass. each could have had a different location and mass. in particular it could have been that A had B’s location and mass and B had A’s location and mass, while everything else is the same. this possibility corresponds to a world w’ that is distinct from w: after all, worlds where an object A has distinct locations are distinct worlds. but w’ is physically identical to w. so physicalism holds in w but supervenence fails.

    of course anti-haecceitists, who deny that there can be distinct qualitatively identical worlds, will reject the set-up — but surely we don’t want to define physicalism so that it is incompatible with haecceitism (probably the dominant view of de re modality). an alternative possible moral here is that physicalism requires that all truths are grounded in physical truths, but that grounding does not obviously entail necessitation. another possible moral is to distinguish two notions of metaphysical possibility, one according to which there are two distinct metaphysical possibilities here and one according to which there are not. i’m inclined to endorse both of these morals. but this issue does suggest that the connection between physicalism and supervenience is not an open and shut case.

  11. Gene, I don’t think we’re talking past each other, at least not irredeemably so.
    You say that physicalism implies a kind of anti-pluralism. The only kind of anti-pluralism I can see it implying is that everything must be physical. But we can get that even if, as you put it, “all the all the distinguishable kinds of phenomena are metaphysically independent of each other.” Putting aside my earlier worries about whether physicalism should be consistent with the existence of God (as well as other worries about just how unique something has to be in order to count as unique), let’s say that the core idea of physicalism is that all entities and properties are not uniquely nonsupervenient on the realm of physics. To be physical, on this view, is to be not uniquely nonsupervenient on the realm of physics. This kind of physicalism is therefore anti-pluralistic since it holds that everything is physical yet consistent with there being a various and sundry metaphysically independent phenomena.

  12. Thanks, Dave, for pointing out a possible benefit of my way of looking at things! I do allude to this issue briefly in a footnote saying that if what I am arguing is correct, physicalists could consistently accept that haeccietistic properties fail to supervene on the fundamental physical properties, and your comment makes me think that this idea might be worth developing further. As for the two possible morals, I would love to hear more about them (and I suppose I will, if not here, then at the Pacific APA). The first one seems like a reasonable take on physicalism, sort of along Quinean lines (though as I mentioned—or perhaps mentioned only in the full version of the paper—I think one just might want to question even this). The second one, I definitely need to hear more about…

  13. cool — is this the paper i’m commenting on at the pacific APA? i don’t think i’ve gotten anything yet.

    here’s a bit more on those points from my book manuscript “constructing the world”:

    We know that the truths in question necessitate all *qualitative* truths, but one might think that the metaphysically fundamental truths should necessitate *all* truths. Matters are not entirely clear here, however. In practice, many philosophers at least implicitly take it that necessitation of object-involving truths is not required. For example, physicalists often allow that microphysical truths do not necessitate object-involving truths (that is, they allow that there are microphysically identical possible worlds involving different objects) without taking this to threaten physicalism. The issue is subtle. If the stronger thesis is required, then the move from necessitation to fundamentality will require either ruling out haecceitism or else fleshing out the necessitation base with certain object-involving truths (object-involving truths about certain microphysical objects, for example) so that the base becomes a full necessitation base. For present purposes, however, I will take it that at least one interesting sort of metaphysical fundamentality is compatible with failure to necessitate non-object-involving truths.

    Footnote: See Hofweber 2005 and Almatohari and Rochford 2011 for differing perspectives on this matter. My view is that even if object-involving truths are not necessitated by underlying qualitative truths, they may nevertheless be grounded in underlying qualitative truths. For example, suppose there are just two particles. Then the fundamental truth about the world might take the form $\exists x \exists y: x \neq y & Fx & Gy$. There may also be object-involving truths about this world of the form $Fa$ and $Gb$, but I do not think it is compulsory to see $Fa$ and $Gb$ as the fundamental truths here. Instead, they may themselves be grounded in the existential truths. This requires rejecting the standard view that existential truths are always grounded in object-involving truths. This view is consistent with a haecceitistic view on which there is a distinct world in which $Fb & Ga$. In effect, once there are objects in our world, we can use them to characterize various counterfactual possibilities involving them, but the original objects are nevertheless grounded in qualitative matters. More deeply, I think one can distinguish notions of prior and posterior metaphysical possibility here: there are multiple posterior metaphysical possibilities consistent with the existential truths, but only one prior metaphysical possibility. While haecceitism may be true of posterior metaphysical possibility, it is prior metaphysical possibility that is relevant to questions of grounding.

  14. Yes, Dave, indeed, this is the paper you’ll be commenting on at the Pacific APA. I’ll get the latest version of it and the power point to you soon.

    As for haeccietism, thanks for that. McLaughlin, if I recall, in his “On the Limits of A Priori Physicalism” seems to indicate that most physicalists were happy to reject it. Do you disagree with this?

  15. wel’ll have to do a philpapers survey! but my sense is that construing haecceitism as the view that there are distinct qualitatively identical possible worlds containing different objects, there are at least as many haecceitists as non-haecceitists about possible worlds, even among people who consider themselves physicalists. prima facie the arguments for haecceitism are pretty strong: for distinct objects A and B and an appropriate maximal property phi, A could have been the phi, B could have been the phi; so there’s a world where A is the phi and a world where B is the phi; if A had been the phi B wouldn’t have been the phi; so these worlds are distinct. one can avoid the conclusion by counterpart theory or other fancy footwork, but if one takes de re modality more seriously than this (as i think the majority do) the argument becomes fairly hard to resist. i think the right moral is to accept haecceitism about “counterfactual space” but to deny that this has serious consequences for the metaphysics of actuality.

  16. Barbara –

    Your last comment is helpful. So you’ll agree that anything deserving of the name “physicalism” is going to imply that (in SOME sense) everything is physical. Then you offer a way to understand that so it’s consistent with the pluralist situation I was worried about. Your key move is this suggestion:

    “To be physical, on this view, is to be not uniquely nonsupervenient on the realm of physics.”

    But I have to say I find it very hard to believe that this characterization of physicality could fit how people have been thinking about physicalism. The main reason is that this way of characterizing ‘physical’ makes the status of physicality depend on things that seem quite irrelevant. On this view, whether a kind K of entity is physical depends on whether or not other non-K things are supervenient on the realm of physics. That gives us some very strange consequences.

    Let me illustrate. Let the things in the realm of physics be of kind P; let the mental be M; let the chemical be C and biological be B. In addition, however, let us suppose there are kinds X and Y. These are things that are nothing like P-things. Nor are they mental; they are just some other weird alien kinds of properties we know nothing about. (They’re not actually isntantiated.) They’re metaphysically independent of every other kind of thing.

    Now consider two worlds w1 and w2 such that:

    (1) In w1, there exist things of kinds P, C, B, and M. C and B supervene on P, but M does not. Here, M is uniquely nonsupervenient and hence not physical.

    (2) In w2, there exist things of kinds P, C, B, M, X and Y. C and B supervene on P, but M, X, and Y do not. M is no longer uniquely nonsupervenient and hence counts as physical.

    So while M is not physical in w1, all we have to do is add a bunch of further nonsupervenient kinds of things and M becomes happily physical?

    Surely this is not a consequence we want. We don’t want a dualist to be able to say, “Hey, I’m not really a dualist. I mean, I’m not rejecting anything I said before, but I happen to believe, in addition, in lots of other independent properties. Now it turns out I’m really a physicalist!”

  17. Interesting comment, Dave. So the moral I’m reaping (at least right now, before I’ve thought about what you say in more detail) is that my rejection of a necessitation type of supervenience as a necessary condition for physicalism is one, but only one, way for physicalists to accept haecceitism, which is view that is at least prima facie attractive, whether or not you are a physicalist.

  18. I think you make a good point, Gene, and that is why I said that I was putting aside worries about just how unique something has to be in order for it to count as being unique. That is also why I also say in the full version of the paper (as well as something very close to this in the version posted here) that “if what really matters to physicalists is that the mental fits into our world more or less like the chemical, the biological and the geological, the quarks-and-leptons-only possibility and the-physical-sciences-only possibility should be, in and of themselves, perfectly, physically acceptable.” (I say “in and of themselves” since I don’t rule out the possibility that there are other factors, like the existence of God, that could make such a situation unacceptable.) In my answer to you above, I supposed that the core idea of physicalism is that all entities and properties are not uniquely nonsupervenient on the realm of physics in order to show that there could be a kind of physicalism that everything is physical yet consistent with there being a various and sundry metaphysically independent phenomena. I don’t, however, take this to be the core idea but do think that it comes close to a useful necessary condition for physicalism. But what, then, what do I think the core idea is? I’m working on this, but perhaps in your counterexample the reason why the view still seems nonphysicalistic is that the type of mentality in the world is the type that suggests a creator. So I’m still standing by this very vague idea of physicalism being about rejecting phenomena that suggest special consideration as getting at the core of physicalism.

  19. David,

    In your thought experiment, w is a “purely physical world”, and worlds w and w` are “qualitatively identical”, yet objects A and B have their masses and locations swapped. It is supposed to follow that not all of w’s facts supervene on w’s profile of physical facts. After all, w’s hacceitistic profile doesn’t supervene on w’s profile of physical facts.

    However, you must be assuming that w’s physical facts don’t include its hacceitistic facts; after all, if it did, then w’s hacceitistic profile would trivially supervene on its physical profile.

    But I think it’s not so obvious that physical facts shouldn’t include hacceitistic facts. For even in our world there is reason to think that contemporary physics incorporates hacceities.

    After all, it’s well-established that bosons do not obey the Pauli exclusion principle: arbitrarily many bosons can occupy the same quantum state (this includes occupying the same place at the same time). All of their properties, including their relational properties, are the same. Why would physicists say this, if they didn’t think particles had hacceities?

    Now, one might resist the claim that physicists are committed to hacceities on the grounds that multiple bosons in the same quantum state would each have “different histories”, so that their space-time worms would differ. Thus, assuming perdurantism, the particles would not have all the same properties, as their space-time worm differences would render them distinct, thereby eliminating the theoretical motivation to postulate hacceities.

    As a rebuttal, however, one could either reject perdurantism, or else defend the possibility of a world where two bosons are in the same quantum state for their “entire histories”. Either way, a correct physics would be committed to hacceities. Again, the lesson would be that the world’s hacceitistic profile would trivially supervene on its profile of physical facts.

  20. james: good point. though (i) to be committed to distinct qualitatively identical objects is not yet to be committed to haecceitism, as i understand things — that requires being committed to distinct qualitatively identical worlds. (ii) it’s not obvious that macro haecceities must supervene on micro haecceities, which is what would be relevant here. (iii) most fundamentally, i’m inclined to think that a “qualitative physicalism”, holding that all truths are grounded in qualitative (non-object-involving) physical truths could be true, even if object-involving truths don’t supervene on qualitative physical truths.

  21. It seems to me that Dave makes some good points here, however, James brings out an interesting issue (whether it is directly related to Dave’s concern’s or not): what else could it be besides a haecciety that make one boson distinct from another?

    On another matter, I know the conference is just about wrapping up here, but I was wondering if anyone might comment on this idea:

    Consider the possibility that the relation between the brain and the mind is probabilistic. Imagine, for example, that only 5/6 of normal human beings, as a matter of chance, are conscious. The existence of consciousness in any particular human, in such a situation, is simply a chance occurrence. Perhaps there is a theory that predicts that this is so; it would not be able to predict whether any given person is conscious but, given a large number of people, would be able to tell us roughly how many conscious individuals there would likely be. Or perhaps there is no such theory and that we have no way of knowing who is conscious, if that nearly 17% were generally behaviorally indistinguishable from the rest. (I do not, of course, mean to suggest that the world is like this. However, if it were, it could be one explanation for why a certain proportion of philosophers—1/6, perhaps—claim to deny the existence of consciousness!) What follows about the truth of physicalism? It seems to me, that if the relation between consciousness and the brain were only probabilistically specifiable, this would be remarkable. But I’m not sure that it is so remarkable that it would mean that physicalism is necessarily false. Yes, again, God—perhaps introducing a law linking neural states to chances of mental states—but as I argued before, this, as I see it, is not a problem.

    In this situation we seem, though, to have a unique failure of the supervenience of the mental on the phenomena of physics. So perhaps it’s not quite right to say that a necessary condition for physicalism is that the that mental is not uniquely nonsupervenient upon the physical? Of course, quantum mechanics, itself, is, according to our best understanding of it, deeply probabilistic. Although we can specify the average radioactive decay rate of a large number of similar atoms, for example, when a particular radioactive atom will decay is a matter of chance. Yet this does not show that physicalism is false. Perhaps the quantum mechanical probabilistic theory of the fundamental nature of the world is wrong. But what is relevant is that it seems compatible with physicalism. And so, more generally, it seems that the existence of events that are fundamentally probabilistic is compatible with physicalism, even, perhaps, if this fundamental probability lies at the level of the mental. So it still seems to fit into the world in a way similar to other features of the world.

    If I’m willing to go this far, however, why shouldn’t I say that even the non probabilistic, unique total failure of the mental to supervene on physics does not refute physicalism? After all, we do not require that physics has a supervenience base other than itself. Does the existence of a fundamental level that cannot be explained in terms anything more basic nor is determined by anything more basic suggest a creator? Some think it does. However, it does not seem to necessarily suggest a creator who had human beings in mind from the get go. But is this really relevant? Any thoughts would be appreciated.

  22. David,

    Thanks for the reply, and good points.

    I am a Buddhist about composite objects. I don’t think composite objects are even possible in any interesting sense; so I agree with your first two points, and maybe also your third point.

    Particularly, I agree with your third point if you’re simply imagining a possible world where there are no object-involving truths that supervene on qualitative physical truths, which is consistent with there being no (positive) object-involving truths at all.

    At any rate, I was trying to steer the discussion towards particles, instead of composite objects. One might imagine qualitatively identical worlds whose particle hacceities are swapped around a bit. Yet if a correct physics were to specify its world’s hacceitistic profile, its hacceitistic facts would trivially supervene on its physical facts.

  23. Barbara,

    Sorry to be coming in so late. Most of my reaction has already been said by others, so I’ll just respond to the last paragraph of your Feb. 29, 21:23 comment.

    One thought I’ve had all along is that “physicalism” will be a useless term unless something counts as non-physical. So, it’s important to ask what would count for you as non-physical. And I thought I knew your answer: *Unique* failure to supervene on the narrowly physical. — I agree with others who have pointed out highly counterintuitive consequences of adopting such a criterion, but at least it gives us *something* with which to contrast the physical.

    But in the last paragraph of your recent comment, you seem to be contemplating giving this up, and flirting with a new criterion for being non-physical — namely, X is non-physical iff the supposition that there is X suggests special creation by a god.

    I find this dismaying. I’m a dualist (for phenomenal qualities, not for beliefs and desires), and I’m an atheist. I don’t think my reasons for dualism even so much as suggest the idea of a special creator. If this new criterion for non-physicality were adopted, I’d have to say I’m a physicalist. All that would mean is that I’d have to think up a new word to express what others believe and I deny. Surely, there can be no philosophical profit in that.

  24. Thanks for those thoughts, Bill. My immediate response is that although your reasons for being dualism may not even so much as suggest the idea of a creator, dualism itself does. It suggests that the world was made with human beings in mind. Or at least a traditional Cartesian dualism does this. Panpsychism, perhaps less so….

  25. Just wanted to thank you all for your comments and to thank Richard for being the master mind behind the conference. It’s been tremendously helpful and quite a bit of fun.

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