Non-reductive physicalism consists in the joint theses of non-identity and supervenience. And this leads to big trouble. That’s the short version. Here’s the longer version:Â
Non-reductive physcialism is non-reductive because it holds that no mental property is identical to any physical property. Call this the non-identity thesis. It is physicalist because it holds that there can be no differences without physical differences obtaining. Call this the supervenience thesis. So, for example, if a and b differ with respect to the mental properties M1 and M2 that they instantiate, they must do so in virtue of instantiating some distinct physical properties P1 and P2.
Here’s where problems arise. The demands of supervenience don’t require only that mental differences give rise to physical differences. All differences must give rise to physical differences. (That’s what “no difference without a physical difference” means.) It follows then, that if the thesis of non-identity holds, there is sense to be made of the question of in what consists the difference between M1 and P1. If they are distinct, there must be some physical difference in virtue of which they differ. Call that P3. P3 also must differ from M1, otherwise non-identy is violated. P3 must further differ from P1, otherwise there would be no physical difference in virtue of which M1 and P1 differ. So the difference between M1 and P1 demands the positing of a distinct property, P3.
Since P3 is distinct from M1, the question again arises of in what consists the distinction and the answer will involve P4, which by similar chains of reasoning will lead to P5 and P6 and so on. This, I assume, is a bad thing.
Fans of non-identity should give up on physicalism altogether. Fans of physicalism should embrace identity theory.
An interesting argument, but I am worried it might trade on an ambiguity in ‘is’.
To understand your argument, I’ver tried to come up with a counterexample. Consider some mousetrap and its description at the level of physics (or whatever), call that low-level description P1. THe property of being a mousetrap is not identical to P1. Some extra ingredient, P2 is needed to make it a mousetrap. Etc.
My mousetrap example, which uses similar logic to your argument, seems unsound. Wouldn’t a functionalist just say your argument is like the mousetrap argument?
One thought: it seems when we say that the mousetrap ‘is’ P1, we should interpret the ‘is’ as the ‘is’ of predication, not of identity. The functionalist wants to give a general description of what makes all mousetraps what they are, to justify subsuming them under the same predicate. Similarly for the mind.
Have I missed something?
Hi Eric,
Thanks for the comment. I think the argument can be made with “is” unambiguously reserved for the “is” of identity and the “is” of predication replaced with the having of properties.
So, if supervenience is true then for each distinct property an object has (M1, M2,..), there must be distinct physical properties (P1,P2,…) that it has in virtue of which the initial distinctions obtain. If the non-identity thesis is true, then M1 is not P1.
Regarding mousetraps: If object t is a mousetrap, then it has property M, the property of being a mousetrap. If there is no physical property P that t has that M is identical to, then, on pain of regress, you better not embrace the thesis of supervenience.
For what it’s worth: I prefer supervenience and thus reject the claim that trapping mice is a non-physical thing for a device to do.
Thanks for clarifying things. I still need to mull it over, as it has a sleight-of-hand feel to it (it’s just too simple to be right!).
So I am right to say your argument can be used for any property, such as the property of being a mousetrap or a heart?
Yes, it can be used for any property. By which I mean: for any property that supervenes on the physical, there is some physical property that it must be identical to.
[F]or any property that supervenes on the physical, there is some physical property that it must be identical to.
This is a very interesting claim, and the key. I think the key objection you will get is that disjunctions of physical properties are not physical properties (e.g., the property of being a mousetrap is identical to the property of being a spring-loaded wire on a wooden board OR A poison-laced piece of sticky paper OR…, and this disjunctive property is not physical). I am not sure how I feel about this objection. Is the property of being ’spin up xor spin down’ physical? Yes. How about the property of being an ‘Electron or a brick’? It is not all that clear to me.
I tend to doubt that the reductive physicalist is forced to embrace disjunctive reductions. At least, I’m not persuaded by so-called multiple realizability objections that this must be so. Consider the property of moving at a speed of 55mph. Things with diverse chemical compositions can do that–pieces of ice, chunks of gold, etc–but this doesn’t suffice to make moving at that speed a disjunctive property. It’s just a single non-disjunctive physical property.
I agree that multiple realizability doesn’t imply that identity theory is false (solidity, brittleness, temperature etc are all multiple realizable but physical properties). However, in such cases we know the physical property that all instances have in common. With things like mousetraps, it is not as clear that there is a straightforward physical-level description other than the disjunction.
For consciousness debates, this isn’t that important: arguments to the effect that consciousness is more like a mousetrap than like temperature are not very strong, and functionalism has too long ridden on the coattails of facile multiple realizability arguments. However, it seems that your general claim, that any property which supervenes on the physical is identical to some physical property, seems weakened by kinds like mousetraps (unless disjuncts of physical properties are physical).
Note I am not convinced by my argument, but I was just wondering what you’d think of the stock functionalist reply.
One way of seeing the upshot of regress argument is that if it is true of a thing that it is a mousetrap, then that right there is a straightforward physical-level discription of the thing. The possibility is left open that the long disjunctive list is not the physical-level description of the thing but just a list of various physical properties with respect to which things may differ while still instantiating the physical property of being a mousetrap.
I bring this up not because I think it is necessarily right. Maybe disjunctivism is ok after all. However, if one had reservations about disjunctivism, one could still embrace the conclusion of the regress argument.
[...] At this point the property dualist may be feeling that the problem posed applies only to substance dualists. The property dualist may think they can help themselves to physical differences between individuals in a way that the substance dualist cannot. What distinguishes numerically distinct yet mentally identical individuals? The property dualist may think that they can answer “physical properties” as easily as the physicalist. However, this is not so. Consider the question of a world in which there are two distinct minds but only one body (with only one brain). If mental properties are indeed distinct from physical properties, then the dualist would have no grounds for ruling out the absurd situation of multiple numerically distinct yet qualitatively identical minds inhabiting the same body/brain. And if the property dualist thinks they can help themselves to supervenience at this point, then they face the problem of regress discussed previously here. [...]
I can’t follow what you are assuming about property identities in this argument. But one thing I can see is that you seem to be assuming only local supervenience, whereby the M properties of a thing are taken to supervene on the P properties of that very thing. This rules out global forms of supervenience, and particularly forms in which even the individuals of the supervening vocabulary can’t be identified with the individuals of the subvening vocabulary (as in Haugeland’s “Weak Supervenience” and examples therein).
Anders,
I don’t see that my argument depends on local supervenience. What lead you to believe that it does?
Well I don’t really understand it, I was only making a guess at what you were arguing.
Let me try being a little more concrete. Suppose we hold that economic facts supervene on physical facts. That means that if there are two possible worlds such that some economic fact is true in one but not in another, then the worlds must differ in some physical fact.
Now what I don’t understand is your claim that “All differences must give rise to physical differences.” Supervenience as best understood is concerned primarily with differences of fact or statement, not properties directly. Suppose an individual Jones is a millionaire in one world but not another. Then we know there must be some physical difference between the worlds. But this need not be any local structural difference in Jones. It might be due entirely to his turning 21 and coming into a trust fund established long ago and far away in one world, but not in the other, which has not causally affected his development yet. Still, the events that established this did involve molecules moving differently in that world at that distant time. So global supervenience is maintained.
Now someone holds, plausibly enough: the property M of being a millionaire can’t be identified with any physical property. Well so what? You say: “It follows then, that if the thesis of non-identity holds, there is sense to be made of the question of in what consists the difference between M1 and P1. If they are distinct, there must be some physical difference in virtue of which they differ. Call that P3.” I don’t see how that follows from the definition of supervenience I am using. You need to find some difference in facts in two worlds before you can mobilize the definition.
I suppose it is a fact that for all physical properties P, ~(P = M). But that could be taken to be a necessary truth, one holding in all possible worlds.
So I don’t see where a difference in facts comes in to let you make use of the definition of supervenience.
Anders,
I don’t see that much hinges on the fact vs. properties stuff. Formulating supervenience in terms of properties is pretty standard (see http://plato.stanford.edu/entries/supervenience/. For more on me on supervenience, see: http://philosophy.uwaterloo.ca/MindDict/supervenience.html.
True there are many different definitions of supervenience, but some of the distinctions among them do make a difference. I think some of them are too strong to be plausible as an account of the supervenience of mental and physical. Twin Earth style arguments seem to me to show that it has to be global supervenience, as in the economic case, since psychological facts (including phenomenal facts) fail to supervene on local brain or physical structure. And I don’t see how your particular argument can be run under global supervenience. If it talks about the M differences of some thing supervening on the P differences of that very same thing, then it is too strong, since psychological differences among physical structural twins can be like economic differences, supervening only on very remote physical facts about their environments.
But I think I now see the more fundamental flaw. Consider a form of supervenience that says that no two individuals can differ in mental properties without differing in some physical property. Now we say that properties M1 and P1 are non-identical. You say, in effect: well, M1 and P1 are also individuals, so, by supervenience, M1 and P1 must differ in some physical property.
But that’s just confused because M1 and P1 are not individuals at all: they are properties of individuals. So they are not subject to the supervenience requirement.
I don’t believe I have ever heard of a definition of supervenience that would entail that step about properties. If valid, it would make the flaw in non-identity pretty blatant.
Anders,
Re global: To run it for global super v the physical differences can be relational. Or the individuals can be worlds themselves.
Re: what’s subject to the supervenience requirement: Everything is subject to the supervenience requirement. Otherwise, what’s the point of calling non-reductive physicalism “physicalism”?
> Everything is subject to the supervenience requirement. Otherwise, what’s the point of calling non-reductive physicalism “physicalism�
Well nothing hinges on whether it is called “physicalism” or not. But I gather the intuition is to allow that in some sense the physical facts determine all the other facts, so that, as it were, once the gods settled all the physical facts in the world they would not need to superadd any of the other facts, the other facts are settled.
This doesn’t need the premise you are relying on about applying to distinct properties as well as individuals. As I understand it the supervenience intuition requires only that “everything” means every THING, i.e. every individual.
Hi Anders,
Here’s an intuition: : “facts” means facts, and as long as there are facts about property differences, those are facts too. Also, if there are facts about fact differences, those too are facts.
If it is intuitive that all facts are determined by physical facts, then there must be some physical fact that determines the difference between a physical fact and a non-physical fact. Call the three facts mentioned in the previous sentence P1, M1, and P3, and you can see how a fact-based version of the regress argument will go.
> If it is intuitive that all facts are determined by physical facts, then there must be some physical fact that determines the difference between a physical fact and a non-physical fact.
Sorry, I don’t see how this is going to go for a fact-based definition.
I take it “determine” in the supervenience definitions has a similar sense to the one it bears when we say that the argument of a mathematical function determines its value: there cannot exist two worlds such that they are the same in all the subvening facts, but different in one of the supervening facts. Equivalently, if two worlds differ in that some M-fact is true in one but not another, then they must differ in some P-fact (some P-fact must be true in one but not another.)
Now suppose we say it is a fact (truth) F1 in some world W1 about mental property M and physical property P that ~(M=P). Does F1 supervene on the set of all physical facts in W1, call it P_w1? Well, that means there can’t be another world W2 which in which every member of P_w1 holds but but F1 does not hold.
Is that going to be a problem? I don’t see it. In fact one could plausibly say that F1 is a necessary truth, which obtains in every possible world. So you could not even construct two possible worlds that differ in respect of F1’s obtaining, as you would have to to display a failure of supervenience. (Necessary truths supervene on the physical in a trivial way.)
Anders,
It looks to me like you are just begging the question about about what facts count as subvening facts. Of course, it is open to the non-reductive physicalist to simply redefine the supervenience intution so that non-reductive physicalism is immune to the regress argument. But doing so looks pretty ad hoc.
> looks to me like you are just begging the question about about what facts count as subvening facts.
How so? was taking it that the subvening facts could be “all physical facts”, pretty much on any plausible reading of that. I don’t see where anything I said depends on restricting the subvening facts.
It should be clear from the definitions that all necessary truths supervene (for a trivial reason) on the physical, are you denying that?
[...] I’ve been thinking about Chase Wrenn’s third-man argument against realization (here) and my own against non-reductive physicalism (here) and the less-than-fully-baked idea occurred to me to run a third-man against the so-called representation relation. [...]
The difference between any two properties need not itself be a distinct property of the thing in question. So your regress argument is a complete non-starter unless you can show that differences in properties must also be properties. Yet if differences between properties are themselves properties, then the regress problem will plague every thing that has more than one property.
I’m also confused about how I can avoid the conclusion that you’re equivocating on ‘difference.’ The non-reductive position says that there can be no difference between two mental properties M1 and M2 unless there is a difference between the physical properties P1 and P2 that instantiate them. It does *not* claim that because M1 is different from P1, there must be some further physical property. That’s just juvenile equivocation.
So, where are your real arguments against non-reductive physicalism?
Oh, that’s right, YOU DON’T HAVE ANY!!!!!!!!
Hey “Tootie”,
“If differences between properties are themselves properties, then the regress problem will plague every thing that has more than one property”
Yes, I totally agree with that. And so should everyone who doesn’t want to fall into a stupid regress. Unfortunately, if you want to be both a non-reductivist and a physicalist, you don’t get to avoid that.
What’s physicalistic about the non-reductive position that you are defending if doesn’t explicate the difference between M1 and P1 in terms of there being a physical difference between the two? Is it just a brute difference which you call “physicalist” because you feel like it?
The full version of my argument is available here:
http://www.petemandik.com/philosophy/papers/sn.pdf
It’s worth spelling out, I guess, that the construction of the regress doesn’t depend on reification of “being different” as a property unto itself. The relevent notion of differnce can be unequivocally spelled out in terms of failure of identity.
So:
Physicalism requires that no properties can be non-identical without being instantiated in virtue of non-identical physical properties. In the case of non-identical mental properties M1 and M2, they are instantiated in virtue of P1 and P2.
The Non-identity thesis requires M1 be identical to no physical property and thus not identical to P1.
An application of physicalism (”no properties can be non-identical without…”) to M1 and P1 requires the instantiation of P3, which itself is non-identical to P1 and M1.
An application of physicalism to M1 and P3 requires the instantiation of P4…M1 and P4 require P5..and so on to P-infinity.
The regress doesn’t necessarily depend on interpreting P3 as “the property of P1 and M1 being different”. It depends on P3 being identical to neither P1 nor M1.
If you really really like the non-identity thesis, the thing to do is reject physicalism as I’ve characterize it here. However, such a rejection involves having to give different answers to questions of the form, “in virtue of what are two properties different?” depending on whether the properties in question are 1) two different mental properties, 2) two different physical properties, or 3) a mental property and a physical property.
1) In the mental-mental case, the two mental properties are non-identical in virtue of being instantiated by physical properties that are non-identical.
2) In the physical-physical case, the difference is due simply to the two physical properties being non-distinct.
3) In the mental-physical case, the difference is due simply to the mental property and the physical property being non-distinct.
If we ask what’s physicalistic about 1-3, what merits considering the differences in question physical differences, we only get satisfying answers for 1 &2.
For 2, what makes the difference in question a physical difference is that there are two properties that are non-identical and both physical.
For 1, what makes the difference in question a physical difference is parasitic on 2.
For 3, the difference is simply that the properties are non-identical. But since one of the properties in question is non-physical, there seem to be no grounds for regarding the difference in question a physical difference (since neither 1 nor 2 can supply the grounds). Further, there seem to be no grounds for consdering the position in question a version of physicalism. It’s dualism.
This is just a rehash of Bradley’s argument against relations. But today nobody would make much of it. It’s not a vicious regress. On the contrary, it’s a progression. A progression with many virtues. It’s a perfectly fine way to generate an infinite hierarchy of relations.
Eric,
there may be lots of infinite progressions that are nice to have around, but I don’t see why you are in love with this one.
M1 is distinct from P1 in virtue of M1’s being instantiated by an infinite series of physical properties P3-Pw, each of which is distinct from P1. What’s so great about that?
You’re right - I didn’t mean to imply that I’m in love with the Bradley hierarchy. It’s actually pretty trivial. But it’s not a vicious regress.