Call our world (the actual world) "W 1 " and the zombie world "W 2 ." Call the set of W 1 properties in virtue of which W 1 is distinct from W 2 "Φ 1 ," and the set of W 2 properties in virtue of which W 2 is distinct from W 1 "Φ 2 ." Finally, call the set of all the properties in common between W 1 and W 2 "Ω."

Philosophical "zombies" are imaginary beings that are exactly like us, except that they lack "phenomenal" consciousness -- the kind of consciousness that makes it "like something" for us to see, for instance, a red dot. Whereas our world is phenomenally laden, you might say, the zombie world is phenomenally void.

Now imagine a third world, which we'll call (you guessed it) "W 3 ." W 3 is identical to both W 1 and W 2 in respect of Ω. What distinguishes W 3 is that it begins its existential career as a conjunction of Ω and Φ 2 , but then at some time t undergoes a phase change, whereafter it persists as the conjunction of Ω and Φ 1 . In other words, W 3 is phenomenally void until t, and phenomenally laden thereafter.

Suppose that at t minus 1, George 3 , an adult denizen of W 3 , and incidentally a loyal reader of this blog (or rather, its W 3 counterpart), looks at the following dot:

George 3 , at this point still anaqualiac, says aloud: "I am looking at a red dot." (George 3 , like his otherworldly counterparts, has a habit of talking to himself.)

Still curious (at least apparently, for he is furrowed of brow) about where this whole argument is headed, George 3 continues to read on until, at t plus a split second, he reaches the end of this sentence, and again looks at the dot following it:

George 3 again notes aloud, "Well, that's the same red dot as before."

And it is the "same" dot. But of course something has changed: George 3 is actually conscious of seeing the red dot.

Now, by hypothesis, this seemingly striking change in the way of things makes absolutely no difference to George 3 's outward behavior: W 1 , W 2 and W 3 are all identical in their Ω properties, and those properties are supposed to include (at the very least) all observable behavior. However, it is difficult to imagine that George 3 , suddenly endowed with phenomenal consciousness, would not react to this fact in some observable way: "OMFG! I can...see!! I can see the dot!! I mean, really see it!!! [Bursts through the front door, laptop in hand.] Look, everybody! Do you see the red dot?! [Now weeping.] Oh...God -- it's so beautiful!" But...no, the zombie hypothesis has George 3 going on exactly as before, as if nothing at all had changed.

If the counterintuitiveness of the situation at W 3 suggests there is something wrong with the zombie hypothesis, there are at least two lines of response open. The first is simply to concede that W 3 is inconceivable, but point out there's no clear reason W 3 's inconceivability should impede the conceivability of W 2 . [1] The second is to argue that the seemingly incongruous behavioral continuity is explained by some isomorphism between W 1 and W 2 (or W 3 before t and W 3 after t).



The first line of argument at least seems fishy to me. It is true that the apparent incongruity in W 3 is generated by the distinctive "phase change," arguably a feature that makes the distinction between W 3 and the others look like an easy call. But I think this move smuggles in the sort of dynamical assumptions that zombie arguments need to bracket out. [2] The phase change, as I've defined it, doesn't invoke a separate, dynamical, causal element; rather, it simply marks the time of an ontologically brute change in W 3 's career from the era of phenomenal voidness to the era of phenomenal ladenness. That being so, there doesn't seem to be any principled difference between deploying the zombie concept at W 3 and deploying it at W 2 ; W 3 is merely a way of looking at the zombie hypothesis in light of further considerations. If so, and if W 3 is inconceivable, this counterintuitiveness would seem to provide further reasons for (fatal?) suspicion about the zombie hypothesis.



The second line of response, that of appealing to some relevant isomorphism, might go something like this. A given instance of (pseudo)reference to a quale at W 2 supervenes on certain Ω properties, but its outwardly reliable (pseudo)referential success supervenes on some cluster of Φ 2 properties, say φ 2 . This cluster is isomorphic in some way (we will stipulate) to the cluster of "intrinsic" Φ 1 properties, say φ 1 , that subtends the successful reference to the corresponding quale in W 1 . And it's this isomorphism that grounds the behavioral continuity observed in W 3 : the ontological substrate φ 2 of George 3 's memory or representation of "red" at all t minus n subsequently, at t, gets "phenomenalized" (i.e., roughly, replaced with φ 1 ), but this φ 1 -induced phenomenal aspect only "takes the place" that φ 2 held, and therefore doesn't "add" anything that should cause George 3 to behave differently.

But this tack raises two new concerns. First, it construes "intrinsic" properties, which are supposed to be nonfunctional, in a very functionalistic way: the isomorphism between Φ 1 and Φ 2 is cast as the "normalizing" factor in George's behavior.



Second, it is in tension with a view about phenomenal judgment, advanced by David Chalmers, according to which our knowledge claims regarding qualia are justified all and only by the "intimate epistemic relation" we have to our qualia experience. Here, however, the justification for George 3 's post-t judgment about red can't be justified by his acquaintance with it, because by hypothesis he'd never before been acquainted with it. Yet (for all that) George 3 's judgment seems perfectly justified. If that's right, then zombie advocates owe us some other account of justification for phenomenal judgments.

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NOTES

1. I am ambivalent about whether zombies are ideally conceivable, but have argued elsewhere that to whatever extent they are, their conceivability only undermines the force of the argument from the possibility of zombies to the potential explanatory efficacy of "nonphysical" or "intrinsic" properties.

2. See Peter Bokulich's "Putting Zombies to Rest: The Role of Dynamics in Reduction" (pdf).