A number of philosophers working on mental causation have adopted something like Yablo’s account of proportionality even while avoiding committing themselves to the specifics of Yablo’s counterfactual-based account or even while explicitly rejecting those specifics in favor of a non-counterfactual-based approach to causation.273 Seeing how this might work will help us distill what I regard as the underlying thought behind proportionality. So then, imagine a new type of Yablo defender who concedes that last section’s argument shows that Yablo’s account is flawed as it stands, but who insists that Yablo is still getting at something importantly right. According to this defender, a crucial fact about the Gilmore case is that even if PH* realized pains are never accompanied by sobbing at Gilmore’s world, it is still generally the case that sobbing accompanies pain there. Again, there seems to be something like a ceteris paribus law (or generalization, at least) linking pain and sobbing there.
According to this defender, the underlying idea we ought to take from Yablo is that in order to determine whether a putative instance of mental causation is genuine, we need to look around at what happens when mental states of the same type as the supposed mental cause are differently physically realized. In the Gilmore case this amounts to looking at what happens when pain is realized by something other than PH instantiations. Now, the way Yablo attempted to capture this idea of “looking around” at alternative physical realizers was by using counterfactuals like (Sob). If there are problems with his attempt – as last section showed that there are – then the proper response is not to reject this idea of looking around but rather to find some alternative way of capturing it.
8.3.1 A SIMPLEMINDED APPROACH
One usefully simpleminded way we might try to retain this looking around idea is by adopting the following view. To determine whether an instantiation of a mental property M causes an instantiation of E, divide M’s physical realizers into two camps: (i) those that causally necessitate E instantiations, and (ii) those that don’t. The putative mental causation is genuine just in case the number of physical realizers that falls into camp (i) is more than the number that falls into camp (ii). In the Gilmore case, PH, PM, and PM* all belong to (i), while only PH* belongs to (ii). Since three is more than one, we ought to conclude that Gilmore’s pain causes his sobbing. On the other hand, reconsider the beeping PH-detector case. There, only PH belongs to (i), while PH*, PM, and PM* all belong to (ii). Since one is less than three, we ought to conclude that Gilmore’s PH instantiation and not his pain causes the detector to beep. What this simple counting approach illustrates is that there are ways to retain the spirit of proportionality, the idea of looking around at other physical realizers, even while dropping counterfactuals like (Cry) and (Beep) from one’s account entirely.
I now will try to show that Yablo’s core problem lies with this looking around idea, not with his use of counterfactuals. Any account, like the simple counting approach just set out, that attempts to incorporate this idea will be susceptible to variants on the counterexample presented in the preceding subsection. To establish that this is so, let me construct a new, starker, Gilmore case.
8.3.2 GILMORE’S ANXIETY
In order to alleviate his toothache, Gilmore schedules a trip to the dentist. In the hours leading up to his appointment he experiences an intense anxiety that putatively causes his heart to race. Let’s suppose that there are four nomologically possible physical realizers of anxiety: PH’, which realizes anxiety in all human beings (including Gilmore); PM’, which realizes it in all Martians; PV’, which realizes it in all Venusians; and PJ’, which realizes it in all Jupiterians. Let’s also suppose that PH’ causally necessitates an accelerated heart rate. Finally, let’s suppose that the alien species in question are biologically different from us in the following ways: Martians don’t have hearts, they have glowing orbs instead; Venusians have hearts, but hearts which are made of silver and always beat at the same rate; and finally Jupiterians have hearts physically indistinguishable from our own, but the wiring connecting their hearts to their brains is completely different from ours, so Jupiterian hearts actually decelerate when they experience anxiety.
The upshot of all this is that at Gilmore’s world, it is only when anxiety is physically realized by a PH’ instantiation that it is accompanied by an accelerated heart rate. So then, letting ‘A’ stand for the proposition that Gilmore is in anxiety, ‘PH’’ for the proposition that he is in PH’, and ‘H’ for the proposition that his heart rate accelerates, the following analog to (Sob) is presumably false.
(Heart): (A & ~P1) > H.
More importantly for present purposes, however, is this. No matter how, exactly, we try to cash out Yablo’s guiding idea of looking around at how things go with alternative physical realizers, it seems that any account of mental causation that attempts to incorporate that idea will be forced to rule that Gilmore’s anxiety does not cause his heart rate to accelerate, his PH’ instantiation does. Take the simple counting approach, for instance. One is less than three, and so according to that approach Gilmore’s anxiety does not cause his accelerated heart rate. So much the worse for that simple counting approach, I say. And more generally, so much for accounts of mental causation that incorporate Yablo’s looking around idea.
For all we presently know, it may turn out that the actual world is just like Gilmore’s world. Would discovering that there actually are aliens whose hearts are made of silver and always beat at the same rate (for instance) put any pressure on us at all to deny what presently seems obviously true, that in us at least, anxiety causes accelerated heart rates? Clearly not, it seems to me. However it is that attributions of mental causation work exactly, they just are not hostage in this way to the future discoveries of alien biology.