Normativism and Mental Causation by Justin Thomas Tiehen, B. A. Dissertation



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5. Physicalism

I take the most serious problem facing antireductionistic accounts of normativity to be that they stand in apparent tension with our contemporary scientific worldview. Here and in effect throughout the remainder of this work, I will be arguing that this is not so. More specifically, what I will be arguing is that my antireductionism about normativity and thus belief is compatible with at least a moderate form of physicalism. Establishing that this is so would by no means establish that antireductionism about normativity is completely lacking in problems. However, I believe that it would establish that the most daunting challenge facing antireductionists is one that can be met.



5.1 Supervenience

Let’s begin with normative antireductionists’ acceptance of the thesis that normative properties metaphysically supervene on non-normative properties. For our purposes, it will be convenient to formulate this thesis using the “possible worlds” analysis of strong supervenience.154

Normative Supervenience: for any objects x and y and any metaphysically possible worlds w and w’, if x in w is non-normatively indiscernible from y in w’ (i.e., if x instantiates all the same non-normative properties in w that y does in w’) then x in w is normatively indiscernible from y in w’ (i.e., x instantiates all the same normative properties in w that y does in w’).
Given my acceptance of this thesis, my antireductionism about normativity and thus belief is compatible with the metaphysical supervenience of mental properties on physical properties.155 Though in Chapter 4 I compared my antireductionism about normativity and thus belief with Chalmers’ antireductionism about phenomenal consciousness, here we have a profound difference between the two views. On Chalmers’ view, phenomenal mental properties supervene on physical properties with only nomological necessity.

Often, physicalism has been understood entirely in terms of metaphysical supervenience (or something similar). Complications about alien properties and the like aside, the idea is that physicalism is true just in case everything metaphysically supervenes on the physical: just in case all truths metaphysically supervene on physical truths, just in case all properties metaphysically supervene on physical properties, etc.156 If physicalism is understood in these terms, then my antireductionism about normativity and thus belief is straightforwardly compatible with physicalism, while Chalmers’ antireductionism about phenomenal consciousness is not.

There are reasons to think that physicalism requires something more than just metaphysical supervenience however. In fact, one of these reasons just is that Moore’s non-naturalism in metaethics, which again my own normative antireductionism is partly modeled after, is compatible with the metaphysical supervenience of everything on the physical. “Surely no materialist or naturalist metaphysical position could embrace Moore’s metaethics,” Terence Horgan writes in his attempt to motivate the claim that physicalism requires something more than supervenience.157 We will get to Horgan’s views in time. Here at the outset let me say just that the existence of Moore’s view is not by itself a decisive consideration against those attempts to understand physicalism entirely in terms of metaphysical supervenience. For as I noted in Chapter 4, it’s not fully clear what Moore’s non-naturalism amounts to exactly, and one possibility is that by accepting metaphysical supervenience Moore (unwittingly) committed himself to a metaphysical position that today we would describe as physicalistic.

To get at essentially the same point in another way, imagine that Moore had not poisoned the well as he did by using the label “non-naturalism.” Imagine that he held substantively the same metaphysical view that he actually did but marketed his view as a novel form of nonreductive physicalism. The Moore you are now imagining is me – at least roughly. In what way would this Moore have been making a mistake by calling himself a physicalist? Before we attempt to answer this question, I want to build some of my physicalist credentials up by tracing out a few of the consequences that follow from my acceptance of the metaphysical supervenience of mental properties on physical properties.

5.1.1 CONCEIVABILITY, POSSIBILITY, AND THE DIFFERENCE BETWEEN THE NORMATIVE AND THE PHENOMENAL

I have argued for the conceivability of belief zombies. Assuming now that they are conceivable, how are we to block the antiphysicalistic inference to their possibility? Partly by holding that a conditional version of the normative supervenience thesis we’ve been considering is an analytic truth: it’s analytic that if there are normative properties, they metaphysically supervene on non-normative properties. If this conditional supervenience thesis is analytic then its negation is inconceivable, and thus impossible. Below, this will help us block the inference from conceivability to impossibility. That the conditional supervenience thesis is analytic is not in any way a special commitment of normative antireductionism, but rather is accepted by every remotely plausible metaphysical account of normativity that there is, including all standard versions of analytical reductionism, metaphysical reductionism, eliminativism, non-eliminativist antirealism, etc.158

One way of illustrating the analytic nature of the conditional supervenience thesis is by considering difficult moral cases. For the sake of argument, let’s suppose that the execution of Saddam Hussein provides such a case. That is, let’s suppose that we can feel the pull both of considerations suggesting that the execution was morally justified – Saddam was an especially bad guy – and also of considerations suggesting that it was not – is capital punishment ever justified? Even as we remain undecided regarding which of these two moral judgments to make, one thing is clear. It is inconceivable that another execution could possess all of the non-normative properties this one did – properties like that of being the execution of a person responsible for the death of so many people – and yet differ in moral status from this one. If Saddam’s execution was justified, then any execution non-normatively indiscernible from it must also be justified. If Saddam’s execution was not justified, then any execution non-normatively indiscernible from it will also not be justified. Anyone who denies the supervenience principle being illustrated here can be fairly accused of failing to fully grasp the normative concepts involved.

The analytic status of the conditional normative supervenience thesis leads to deep differences between belief zombies and phenomenal zombies. Even aside from my present effort to block conceivability to possibility entailment, these differences should be stressed. Those who take phenomenal zombies to be conceivable hold that it’s conceivable that a physical duplicate of me could be a phenomenal zombie even given that I myself am not one. The analog to this is inconceivable when it comes to belief zombies. It’s conceivable that all physical duplicates of me (including myself) possess beliefs, and it’s conceivable that all physical duplicates of me (including myself) are belief zombies. But, it’s inconceivable that I possess beliefs while some physical duplicate of me is a belief zombie. That this is inconceivable follows directly from the analytic status of the conditional normative supervenience thesis. When it comes to conceiving of belief zombies, you can turn all the lights on, and you can turn all the lights off. You cannot turn some of the lights off while leaving others on though.

Compare Saddam’s execution on this particular point. It’s conceivable that the execution and all possible non-normative duplicates of it are morally justified. It’s also conceivable that the execution and all possible non-normative duplicates of it are not morally justified – that is, it’s conceivable that they are all justification zombies, as it were. It’s inconceivable, though, that Saddam’s execution is morally justified while some non-normative duplicate of it is not (or vice versa).

There is a real sense, then, in which we cannot keep both a true believer and also a belief zombie of the sort I have discussed before our minds at the same time, as we can keep both a true conscious experiencer and a phenomenal zombie before our minds at the same time. Perhaps this is part of the explanation of why so few philosophers have countenanced the conceivability of belief zombies. Given that we ourselves are true believers, belief zombies are conceivable. Thus, conceiving of belief zombies involves either conceiving of oneself as a belief zombie or, alternatively, ignoring one’s own status as a true believer. As someone who continues to insist that belief zombies are conceivable, I claim that this is something that can be done.

If the conceivability of belief zombies is now starting to sound even more incredible than it originally did, it may be helpful here to introduce Chalmers’ distinction between negative and positive conceivability.159 On Chalmers’ account, a proposition P is negatively conceivable just in case its negation isn’t analytically true – that is, just in case P itself isn’t a contradiction – while P is positively conceivable just in case we can imagine a specific configuration of objects and properties such that given that configuration, P would be true. My focus in this work has been on analytic entailment, and so my claim that belief zombies are conceivable should be understood more specifically as the claim that they are negatively conceivable. In asserting that we can (negatively) conceive of belief zombies, what I am maintaining is just that we can entertain the proposition that belief zombies exist without entertaining a contradiction. Nothing more is involved. When I assert that (normativity-based) belief zombies are inconceivable given our status as true believers, what I am maintaining is that we entertain a contradiction when we entertain the proposition that we possess those normative properties required to be true believers while physical duplicates of us fail to possess these normative properties. That this is a contradiction follows from the analytic status of the conditional supervenience thesis.

I am in no way committed to the further claim that belief zombies are positively conceivable. Perhaps due to contingent limitations on our imagination, we have trouble actively imagining a situation in which belief zombies exist because we have trouble setting aside our own status as true believers. This would not undermine any argument I have made in this work. In fact, it would potentially strengthen my arguments by lessening whatever remaining implausibility there is to my conclusions. If belief zombies were merely negatively conceivable while phenomenal zombies were both negatively and positively conceivable (or even just positively conceivable), this would allow me to acknowledge the intuitive difference between the two without threatening my claim that belief zombies are conceivable (negatively conceivable, that is).

At this point I have endorsed a whole package of claims about what’s conceivable and what’s not, about what’s analytic and what’s not. Do these claims really fit together? In particular, how can I hold that the conditional supervenience thesis is analytically true while at the same time denying that the totality of non-normative truths fails to analytically entail the totality of normative truths? Just so we’re clear, the worry here is not that this combination of views involves an outright contradiction on my part. It’s no outright contradiction to hold that it’s an analytic truth that Saddam’s execution and all of its non-normative duplicates share the same normative status while at the same time denying that the normative status they do share analytically follows from the totality of non-normative truths about them. Still, one might feel that there is a kind of tension here. How can the analytic status of the conditional supervenience thesis be explained given my denial of any more specific analytic entailments from the non-normative to the normative?

When one wonders this, one is falling into the grips of a powerful argument against normative realism: Simon Blackburn’s supervenience argument.160 We can reconstruct Blackburn’s argument as follows. Just as we’ve been supposing, the conditional supervenience thesis is analytically true. Now, that it’s analytically true is something that cries out for explanation. Analytical reductionism about normativity could potentially do the job, if only the open question argument had not conclusively refuted it. No alternative versions of normative realism can adequately explain the analytic status of the conditional supervenience thesis. Certain forms of normative antirealism can, however, and thus we ought to be antirealists about normativity.

At least prima facie, I find Blackburn’s argument fairly compelling. One thing it does is help bring out a potential further difference between Chalmers’ view and my own. While the biggest threat to Chalmers’ antireductionism about phenomenal consciousness is no doubt some form of reductionistic realism about consciousness, it is quite possible that the biggest threat to my antireductionism about normativity and thus belief is some form of normative antirealism, like that defended by Blackburn.

As a normative realist I am committed to rejecting Blackburn’s argument, though I won’t attempt to provide a refutation here. Instead, I just want to say that Blackburn has fairly characterized the lot of the normative realist. Just as Blackburn claims, the conditional supervenience thesis is an analytic truth. And just as Blackburn claims, the open question argument shows that analytical reductionism is not viable. A normative realist who wants to respond to Blackburn’s argument should not pin her hopes on rejecting one of these two premises. But, given these two premises together with my further claim that belief properties are intimately related to certain uncontroversially normative properties, it follows that belief zombies are conceivable even though we can’t conceive of them while taking ourselves to be true believers. Anyone who wants to reject this conclusion must reject at least one of the two premises taken from Blackburn’s argument or sever the tie I claim exists between belief properties and uncontroversially normative properties. Each of these moves strikes me as deeply unattractive, and so I embrace the conclusion.

Returning to the question with which we started this subsection, how do I block the inference from the conceivability of belief zombies to their possibility? By claiming that normative properties actually are instantiated and then appealing to the analytic truth that if there are normative properties, they metaphysically supervene on non-normative properties. These two claims together imply that there are no metaphysically possible worlds in which normative eliminativism is true, and thus that there are no metaphysically possible physical duplicates of me who fail to possess the normative properties required to be a believer. Normativity-based belief zombies are thus metaphysically impossible.

Now that this question has been answered, we can turn the tables on those like Chalmers who claim that conceivability entails possibility (in some sense) by asking a pointed question of our own. Which of the following three claims do they want to deny?

(i): The truth of normative eliminativism is conceivable.

(ii): The falsity of normative eliminativism is conceivable.

(iii): The falsity of the conditional normative supervenience thesis is inconceivable.161
Chalmers (among others) must deny at least one of these three claims since (iii) entails that either the truth of normative eliminativism is impossible or else the falsity of normative eliminativism is impossible,162 while together (i) and (ii) say that these two things are conceivable. Thus, (i), (ii), and (iii) jointly entail that something conceivable is impossible. What’s more, they do so entirely by relying on claims about what’s conceivable and what’s inconceivable.

What we have here is a trilemma. Denying (iii) is not a serious option. Again, every remotely plausible metaethical view accepts that the conditional supervenience thesis is analytically true. Denying (ii) involves committing oneself to an extraordinarily strong form of normative eliminativism. According to those who deny (ii), it’s not that we should deny that normative properties are instantiated just because such properties fail to figure in our best explanations, or because they are queer in a way that fails to fit smoothly with our scientific conception of the world. Rather, according to those who deny (ii), the problem with those who accept that normative properties are instantiated163 in the actual world is that they accept a contradictiona literal contradiction, just like the proposition that some bachelors are married. On this view, given the totality of non-normative truths, it’s analytic that no normative properties are instantiated. Many of the stoutest skeptics of normativity will shy away from defending a claim this strong. Finally, denying (i) involves committing oneself to the truth of analytical reductionism about normativity and thus to refuting the open question argument and closing the is-ought gap. Unless one can stomach one of these three options, one will need to reject the view that conceivability entails possibility.164

5.1.2 SUPERVENIENCE AND REDUCTION

Sometimes philosophers have argued that metaphysical supervenience entails reducibility.165 If so, then my antireductionism about normativity is incoherent. Thankfully, every argument along these lines that I know of relies on premises I am willing to reject. For instance, one might argue that metaphysical supervenience entails reducibility by relying on a coarse-grained conception of properties. As I explained back in subsection 4.2.2, however, I independently reject a coarse-grained conception of properties, and so I reject any such argument. Instead of focusing directly on whether metaphysical supervenience entails reducibility, I think it will be more enlightening to consider whatever other problems my antireductionism about normativity may face. If it faces other problems that are crippling, then the question of whether or not metaphysical supervenience entails reducibility will be moot. If it faces no other problems, however, then this degree of internal coherence could perhaps be taken to suggest that metaphysical supervenience doesn’t entail reducibility after all.

By allowing that mental properties metaphysically supervene on physical properties, I take on a much stronger supervenience thesis than Davidson does. Davidson explicitly accepts the view that mental properties weakly supervene on physical properties.166 We can state this view as follows.

Weak psychophysical supervenience: no metaphysically possible world contains objects, x and y, such that x and y are physically indiscernible and yet mentally discernible.167

Davidson’s reason for accepting weak as opposed to strong psychophysical supervenience is that he takes the existence of psychophysical laws to be entailed by strong supervenience (regardless of whether one accepts a metaphysical form of strong supervenience, as I do, or merely a nomological form of it, as Chalmers does). The reason one would think this is because strong psychophysical supervenience entails that the supervenience conditionals linking physical properties to mental properties will be at least nomologically necessary. If one takes their nomological necessity to mean that these conditionals are laws, it then follows that they are psychophysical laws.168 Since Davidson rejects the existence of psychophysical laws, he rejects supervenience.

Davidson’s rejection of psychophysical laws is closely tied to his antireductionism about the mental. According to the accounts of reduction to which he was responding, (intertheoretic) reduction is to be understood broadly in terms of the derivability of one theory from another.169 In order to carry out such derivations, bridge principles are needed linking the terms from the reduced theory to those of the reducing theory. These bridge principles, it was thought, must express laws. Thus, by denying the existence of psychophysical laws Davidson denies the existence of bridge principle of the sort needed to carry out the reduction of psychology to physics.

Today it is widely thought that reduction requires something more than the existence of such bridge principles together with the derivability of one theory from another. It is often (though not universally) held that in addition, reduction requires property identities.170 If so, or perhaps even if reduction requires something just in the general vicinity of property identities, then my position regarding normativity and thus belief is safely antireductionistic regardless of whether or not I allow that there are laws linking normative and physical properties. Because of this, I’m willing to allow that there are such laws. In doing this, I’m giving up on the anomalousness part of anomalous monism. Given my rejection of the monism part back in Chapter 1, I’ve now rejected both components of the view. I am a “nomological dualist” on Davidson’s taxonomy – though, I should again emphasize, my event dualism is meant to be as physicalistically acceptable as statue/clay dualism is.

Weak psychophysical supervenience is compatible with the nomological possibility of a world physically indiscernible from our own but completely lacking in mentality.171 Thus, if Davidson truly is best read as accepting mere weak supervenience, it follows that his view is compatible with the genuine possibility of belief zombies.172 That is, it’s compatible with the nomological possibility of belief zombies. Upon noting this very consequence, Brian McLaughlin concludes that Davidson’s physicalism is “bland.”173 No doubt, a better thing to say is just that Davidson is no physicalist at all – or at least, that he isn’t a physicalist insofar as he really accepts mere weak supervenience. At any rate, it is clear that the position being defended in this work is more physicalistic than Davidson’s is.

5.1.3 SUPERDUPERVENIENCE

Part of the original idea behind formulating physicalism as a supervenience thesis was that such a formulation promised not to be overly reductionistic. Physicalism doesn’t require reductionism, it was thought. Of course, not every form of antireductionism is compatible with physicalism. For instance, Chalmers’ dualism isn’t. But, according to the original idea, we can use metaphysical supervenience to distinguish those varieties of antireductionism that are compatible with physicalism from those that aren’t. If metaphysical supervenience really is the test, then my antireductionism about normativity and thus belief passes: it’s physicalistically acceptable.

Maybe metaphysical supervenience shouldn’t be the test though. Recently, a number of philosophers have argued for an alterative understanding of physicalism, with Horgan’s discussion of superdupervenience leading the way.174 Superdupervenience is supervenience that’s explainable in a physicalistically acceptable way.175 What counts as a physicalistically acceptable explanation of a supervenience relation? There is room for debate about this.176 One thing that clearly doesn’t count, though, is taking supervenience relations to be primitive. Primitive supervenience relations are by definition unexplainable; a fortiori, they are not explainable in a physicalistically acceptable way. On the other hand, one form of explanation that clearly is physicalistically acceptable is that which is available for the supervenience of causal-functional properties on physical properties. If pain is the second order property of having a first order property that occupies a certain causal role, then pain’s supervenience on first order physical properties is fully explained by facts about those physical properties, and in particular facts about the causal roles they occupy.177

I have denied that normative properties and thus belief properties are causal-functional properties, and so I must deny that the metaphysical supervenience of normative properties and thus belief properties on physical properties can be explained in this way. Can I hold that the supervenience relations my antireductionism leads me to posit are explainable in some other way? In general, I don’t think it’s especially enlightening to cast antireductionists as committed to accepting primitive supervenience relations. For present purposes, however, I’m willing to grant that they are.178 At least for the sake of argument, then, I’m willing to grant that my antireductionism about normativity and thus belief is incompatible with the superdupervenience of everything on the physical. Thus, if physicalism is understood as the thesis that everything superdupervenes on the physical, the position I have defended is incompatible with physicalism.

5.1.4 PHYISCALISM AND MENTAL CAUSATION

The question, then, is whether physicalism really should be understood in this way. I grant that there really are considerations in favor of doing so. If we are forced to posit primitive supervenience relations between belief properties (among other normative properties) and physical properties, then certain ambitions quite common among physicalists will have been frustrated. On the other hand, I think that there are also considerations that speak against understanding physicalism in terms of superdupervenience. Consider the following passage regarding the causal argument, which comes from no less an authority on physicalism than David Papineau.

While some philosophers have supposed that mathematical or moral facts do have physical effects, this is not the normal way to think about them. And, if we do deny that moral or mathematical facts have physical effects, then our causal argument will provide no basis for identifying them with physical facts. I myself think this limitation on the causal argument constitutes a genuine boundary to the proper ambitions of physicalism. I think that physicalism is best formulated, not as the claim that everything is physical, but as the significantly weaker claim that everything which interacts causally with the physical world is physical. This leaves it open that there may be non-causal realms of reality which are not physically constituted, such as the realm of moral worth, or of beauty, or of mathematical truths.179
Passing over the claim about mathematics here and focusing just on normativity, the first thing to note is that Papineau seems to be allowing for the combination of views I first described in Chapter 4: non-naturalist physicalism. This by itself is no consolation for me, since Papineau clearly states that the sorts of views of normativity he has in mind deny that there are causal interactions between the normative and physical realms. I must reject such views of normativity since belief properties are normative on my view and yet surely causally interact with physical properties.

Nevertheless, a thought presents itself here. What if I could show that whatever causal interactions there are between normative and physical properties on my antireductionistic view are physicalistically acceptable? This would seem to secure for me a further physicalist credential. Shifting away from normativity in general and focusing specifically on belief properties, the idea here is that if I could show that my antireductionist account of belief is compatible with a physicalistically acceptable account of mental causation, then that would strengthen the case that my view ought to be regarded as a form of physicalism. That is, if my antireductionism about belief can be combined with a solution to the causal exclusion problem which faces all nonreductive physicalists, then I ought to be allowed into the physicalists’ club.

Think of it like this. I’m trying to inch my way toward physicalism by showing that my position is more physicalistic than various other views. It’s more physicalistic than Davidson’s anomalous monism since it accepts a strong supervenience thesis rather than just a weak one. It’s more physicalistic than Chalmers’ dualism since it accepts that everything metaphysically supervenes on the physical. Now, by granting that the supervenience relations that obtain between belief properties and physical properties are primitive, I’ve moved away from uncontroversially physicalistic views like causal functionalism and toward views like those of the British Emergentists.180 This is unfortunate for my cause since the Emergentists, though not traditional dualists, are not physicalists either. At least potentially, though, there is an important difference between my view and that of the Emergentists. The Emergentists believed in downward causation – causal relations between higher level phenomena and physical phenomena that violate the causal closure of the physical realm. If I could show that my own antireductionism about belief properties is compatible with an account of mental causation that doesn’t require downward causation – that is, which violates neither the letter nor the spirit of the causal closure principle – then this would distinguish my view from that of the British Emergentists

If my antireductionism about belief is compatible with a physicalistically acceptable solution to the causal exclusion problem, then I believe that my position should be classified as at least a moderate form of physicalism. “Moderate” because there is still the incompatibility with superdupervenience. If someone were simply to insist that nothing short of accepting superdupervenience can really qualify one as a physicalist – moderate or otherwise – then I will reluctantly give up the physicalist label. In that case, though, I’ll insist that it be acknowledged that my position is the most physicalistic view out there that falls short of physicalism. Again, it’s more physicalistic than anomalous monism or dualism or emergentism or any other view I know of that doesn’t qualify as a form of physicalism. If in the end my antireductionism about normativity and thus belief isn’t quite physicalism, then I claim it’s nevertheless something near enough to physicalism181 to be scientifically respectable.






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