Been There/ Done That

Wednesday, November 08, 2006

Acting like a Zombie

Daniel Stoljar has a new paper, "Two Conceivability Arguments Compared", forthcoming in PAS. There, he compares these two arguments:

The Zombie Argument:

Z1. Zombies (physical duplicates of us, with different phenomenal properties) are conceivable
Z2. If zombies are conceivable, zombies are possible
Z3. Ergo, zombies are possible

The Actor Argument:

A1. Actors (behavioural duplicates of us, with different phenomenal properties) are conceivable
A2. If actors are conceivable, actors are possible
A3. Ergo, actors are possible

The Zombie Argument (ZA) is used to defeat physicalism. The Actor Arguments (AA) is used to defeat behaviourism, or so Stoljar claims. He argues that reflection on the similarities among these arguments can pose problems for the phenomenal concept strategy.

Stoljar assumes that AA is a good argument against behaviourism. He points out that AA is usually presented to undergraduate students as a sound refutation of behaviourism. He also assumes that AA and ZA are of the same kind, that is, they are both concerned with the inference from conceivability to possibility, and the relation between phenomenal and (some or all) physical truths.

Using these two assumptions, Stoljar argues that the phenomenal concept strategy is committed to rejecting AA. The PC strategy claims that Z1 does not entail Z3, because Z1 has an alternative explanation which does not entail Z3. Stoljar argues that if AA and ZA are of the same kind, then the PC strategy would have to say that A1 has an alternative explanation which does not entail A3, so that AA would not be sound. But AA is sound, he assumes. So the PC strategy is incorrect.

I am working on a response to this argument. My thought is that we can disambiguate AA in two ways:

  • AA*
A1*: Actors are conceivable
A2*: If S is conceivable, S is possible
A3*: If actors are conceivable, then actors are possible
A4*: Ergo, actors are possible

  • AA'
A1': Actors are conceivable
A2': If actors are conceivable, actors are possible
A3': Ergo, actors are possible

I think that Stoljar's argument equivocates on these two readings of the actor argument. For there is no single reading of it that makes both of his assumptions plausible:

Assumption 1 (AA and CA are of the same kind) is plausible only under reading AA*. That is, advocates of ZA take it that the conceivability of zombies entails the possibility of zombies because conceivability entails possibility in general.
Assumption 2 (AA is sound) is plausible only under reading AA'. AA' will be sound if the argument is valid and all the premises are true. Under reading AA' it is uncontroversial that AA' is sound, since it is uncontroversial that A1' and A3' are true. And since A2' is just a material conditional, if the consequent is true, the conditional is true. So it is uncontroversial that AA' is sound. But it is not uncontroversial that AA* is sound: premise A2* is precisely what is at issue in these debates.

Could Stoljar understand ZA in a similar way to AA', so that both assumptions involve the actor argument in the sense of AA'? Let's see:

Z1*: Zombies are conceivable
Z2*: If S is conceivable, S is possible
Z3*: If zombies are conceivable, zombies are possible
Z4*: Ergo, zombies are possible

Z1': Zombies are conceivable
Z2': If zombies are conceivable, zombies are possible
Z3': Ergo, zombies are possible

If we consider ZA' and AA', then we can safely assume that the zombie argument and the actor argument are of the same kind, and we can also assume that the actor argument is sound. Does this pose a problem for the PC strategy?
Well, not really. Because the PC strategy is not committed to saying that AA' is unsound, even if they do claim that ZA' is unsound. The strategy entails that conceivability of zombies is not a reliable guide to the possibility of zombies. It also entails that the conceivability of actors is not a reliable guide to the possibility of actors. But, of course, this is compatible with the claim that actors are both conceivable and possible.

Putting the point in a different way: when we compare ZA* and AA*, if we assume that AA* is sound, then the PC strategy is in trouble because their response against ZA* entails that AA* is unsound too: they will deny Z2* and A2* (which are the same). But, of course, it is very controversial to claim that AA* is sound. In my paper, I plan to argue that Putnam and Block's arguments against behaviourism are not of the form AA*.


Blogger Dan López de Sa said...

Interesting post! I haven't read Daniel's paper yet—btw, this seems to be available online here— but look forward to.

I was a bit confused about your ‘equivocation’ charge at first, given that AA* and AA' seem to be in fact the very same argument—with, in the former case, a premise making explicit what might be the rationale for another premise.

Reading the rest of the post, I think your complaint is rather of the following form: both the zombie and the actor arguments are clearly equally valid. But the defender of the so-perhaps-unfortunately-called 'phenomenal concept strategy' could perhaps claim that the zombie one is, while the actor one is not, sound. This being so in virtue of the fact that the relevant crucial premise A3*(=A2'), could perhaps be substantiated in a way that is independent from ‘conceivability’ considerations of the sort A1*-A2*, and which is unfortunately unavailable vis-à-vis crucial premise Z3* (=Z2').

Have I got you straight here? Are you thus providing this further rationale for A3* that does not work for Z3* in your response? And is your response going to be available online—or at least available from you on request ;-)?

1:44 PM  
Blogger Esa said...

Dan, thanks for this. Briefly:
1-Re AA' and AA* being the same argument or not: plausibly, arguments X and Y are two different arguments when it is possible for one to be sound and the other unsound, at the same time. And this is precisely the case with AA* and AA': if actors are both conceivable and possible, but, say, zombies are conceivable and impossible, then AA* is unsound but AA' is sound.
2-Re the form of the argument: The PC strategy's reply is that ZA is unsound and AA is sound (under reading AA'). (You put it the other way around, I guess it was a typo?). What I argue in my paper, though, is not so much that A3 is motivated in a way that Z3 is not, but rather, that it is coherent for the PC strategist to endorse AA plus assumptions 1 and 2, and reject ZA. She can do this, by endorsing AA', not AA*, of course.

3:46 PM  
Blogger Dan López de Sa said...

Oh, I think I understand what you mean, maybe we were talking past each other. Let me try to see if we agree.

Suppose we have an argument like this:
X1’ blah
X3’ blah
X4’ blah
which is sound. Suppose that someone takes it to be the case that curcial premise X3' is supported by:
X2* blah
but this is not so. Then one can express this by contending that the argument from X1’, X2*, and X3’ to X4’ (or, with some relabelling, from X1*, X2*, and X3* to X4*) is not sound, the soundness of the original one notwithstanding.

Is this what you have in mind when talking about AA’ and AA* being different arguments? I didn't mean to dispute this. I think, though, that it is perhaps more fortunate to state it in terms of which is indeed the ground for crucial premise X3’.

This connects to the heart of the other point. You seem to hold that, the “phenomenal concept strategist” could say, the relevant crucial premise A2’ could perhaps be substantiated in a way that is independent from general ‘conceivability’ considerations. In other words, there might be a kind of motivation for A2’ which falls short of vindicating Z2’. (This would have the result that there would be AA*-kind arguments in the vicinity of AA’ which cease to be sound.) It seems difficult to assess that claim unless some such further motivation is provided, no? This is what I thought you were doing in your response to Daniel. But now it seems that your just making the existential claim, is this right?

Hope we now understand each other better ;-)!

(PS Oh yeah, that was a typo, I meant unsound, sorry!)

4:40 PM  
Blogger Esa said...

Dan, this is very helpful, thanks.
Yes, that is exactly what I meant when talking about AA' and AA* being different arguments. Glad we understand each other now!
I have to think more about your suggestion on how to put the point.
On the issue of what grounds other than conceivability we could have in support of A3 (the possibility of actors), I do mention some options in my paper. I guess that, on my view, this is not so controversial as it sounds to you. As I understand him, even Stoljar could accept that there are other sound arguments for the possibility of actors, independent of conceivability issues. Again, I have to think more about this. I will send you the draft when it is finished (which, unfortunately, could take a while).

4:58 PM  
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