Haecceitism, Materialism, Zombies, and Counterparts
If haecceitism is true, materialism is false. For if haecceitism is true, there is a world w just like ours except that you and I have traded places. By that I don't mean that in w someone with my origin or my DNA or my soul leads a life quite like yours. No, haecceitism holds that it is possible for us to trade places completely, so that in w not only my life is just like your actual life, but also my origin, DNA and soul are just like your actual origin, DNA and soul. w and our world do not differ in any qualitative respect at all. They differ only in facts that essentially involve you or me, such as the fact that in w it's you who is writing this posting. Whatever 'physical' means, it is clear that the physical facts are not of this kind. That's why materialism is false if haecceitism is true: Materialism demands that there is no difference at all between our world and any minimal physical duplicate of it.
Interestingly however, haecceitism is compatible with the view that a complete physical description of our world a priori entails all facts about our world. Let's call this 'type-A quasi-materialism'. Offhand, I would have thought that type-A quasi-materialism implies materialism, but haecceitism proves that that's false. The reason is that for type-A quasi-materialism to be true a lot of interesting a priori truths are needed to get from the physical to the other facts. On the other hand, materialism requires some kind of necessary connection between the physical and the rest. So if all the interesting a priori truths are contingent a priori, type-A quasi-materialism can be true and materialism false.
Consider again the world where you and I have traded places. Even though this world is qualitatively just like ours, we don't wonder whether we live there. I don't wonder whether it's me or you who is writing this posting, and you don't wonder whether you live in Berlin or [insert name of your town/city here]. Given sufficient (qualitative) information about a person, I can infer a priori whether that person is me or not. But if haecceitism is true, you could have had all the properties of which I know a priori that if someone has them then it's me. In two-dimensionalist jargon, haecceitism claims that our terms have surprising C-intensions, but not that they have surprising A-intensions. It claims that there are many truths about other worlds, considered as counterfactual, that are not implied by any complete qualitative description of these worlds; but it does not hold that there are any such truths about other worlds considered as actual. (So there are two different kinds of inscrutability.)
As I lamented in my last entry, extreme haecceitism, the view that anything could have traded place with anything, is compatible with Kripke's account of rigid designators. It is interesting to see how it fares when it is plugged into the common use of Kripkean (i.e. strong) rigidity in arguments against materialism. Many materialists say that pain is identical to some physical process, say C-fiber-firing. If 'pain' and 'C-fiber-firing' are strongly rigid, it follows that they denote the same thing in every world and hence that pain is necessarily C-fiber-firing. But that, so the argument goes, is implausible. For can't we imagine a zombie who undergoes C-fiber-firing but does not experience pain?
If extreme haecceitism is true, it is not at all clear that we can really imagine such a zombie. No doubt you imagine something if you say that you imagine the zombie. But can you be sure that the world you're imagining is a world where the zombie undergoes C-fiber-firing? Couldn't it be a world where the zombie is in a state that merely has all the intrinsic and extrinsic (qualitative) properties of actual C-fiber-firings? If extreme haecceitism is true, this leaves it entirely open whether the zombie really undergoes C-fiber-firing. Maybe in the world you're imagining C-fiber-firing has traded places with the Eiffel tower, or (if states are essentially states) with the temperature of a freshly brewed cup of tea. And are you sure that in the world you're imagining the zombie doesn't have pain? Couldn't it be a world where the zombie is in a state that merely resembles an actual state of non-pain in all intrinsic and extrinsic (qualitative) respects? Perhaps in the world you're imagining pain has traded places with the state of being older than 10 years.
(You might object that a state that doesn't resemble pain in any qualitative respect thereby is not pain. Then I think you misunderstood what I mean by 'qualitative'. Remember, I mean something like 'impure', 'not essentially involving a certain actual individual'. The radical anti-essentialism built into extreme haecceitism holds that anything could have had any property whatever -- but not quite. If 'water' and 'H2O' are strongly rigid and water is identical to H2O then even though water could have been a four-headed animal or a calm summer evening, it could not have been non-identical to H2O. The excluded properties, like being identical to H2O, are what I mean by 'non-qualitative'. Nevertheless, I think the objection is in a sense correct: It clearly seems essential to pain that it has certain intrinsic and extrinsic qualities. I'll get back to that.)
Sure, if extreme haecceitism is true and in your imagined world C-fiber-firing is the temperature of a freshly brewed cup of tea, then there is also a qualitatively identical world where it has traded places with the zombie's state. But how can you be sure that in this world pain is not that very same state? Not by imagining that this state lacks any intrinsic or extrinsic (qualitative) properties. The point is that arguably our imaginings only settle the qualitative aspects of a world (plus perhaps our own location). I can imagine a world where there is only a poached egg. But how am I to find out whether the poached egg I imagine is the Eiffel tower, or my cup of tea, or H2O, or the zombie from your earlier imagination?
At this stage I hope you feel that something has gone wrong. Could a poached egg really be the Eiffel tower? Could H2O really be a calm summer evening? Could C-fiber-firing really be the temperature of a cup of coffee? Isn't it somehow analytic that H2O consists of hydrogene and oxygene, and that C-fiber-firing has something to do with C-fibers? Isn't it incoherent to assume that there could be H2O in a world without hydrogene, C-fiber-firing in a world without material objects, pain in a world without consciousness? It is. There are no such worlds. It's not that they exist but are usually ignored. It really makes no sense at all to assume they exist, just as it makes no sense to assume that there are worlds with married bachelors.
What has gone wrong? Have we refuted radical anti-essentialism, and with it extreme haecceitism? No. What we have proved is that
If radical anti-essentialism is true, then terms like 'the Eiffel tower', 'H2O', 'C-fiber-firing' and 'pain' are not strongly rigid.
Assume 'H2O' is not strongly rigid. Assume instead it abbreviates the description 'molecule composed of two hydrogene atoms and one oxygene atom'. Then it is clear why it is incoherent to suppose that there could be a world where H2O is not composed of two hydrogene atoms and one oxygene atom: Asserting the existence of such a world is asserting an implicit contradiction. But that poses no threat to radical anti-essentialism, just as it is irrelevant that there is no world where the biggest planet (of that world) is not the biggest planet (of that world). Radical anti-essentialism only claims that the stuff that is actually H2O and the thing that is actually the biggest planet could have been different in all kinds of ways. If 'H2O' isn't rigid then in a world where the stuff that is actually H2O has traded places with a calm summer evening, or with the stuff that is actually gold, 'H2O' needn't designate the evening or the gold-like stuff. It can still designate the stuff with the H2O properties.
The result is that extreme haecceitism makes Kripke's account of proper names (and stuff terms) share the fate of Russell's account: While there are some terms that behave as the account says -- 'I', 'you', 'that' and rigidified descriptions like 'the stuff that is actually H2O' are good candidates; let's call them 'logically proper names' --, most ordinary names (and stuff terms) do not. Most ordinary names and stuff terms are not strongly rigid: Their other-worldly denotation is restricted by the qualitative features of the other-worldly things.
(Still, there seems to be a difference among the remaining terms: Though none of them are strongly rigid, some of them, like 'the Eiffel tower', appear to be more rigid than others, like 'the largest tower in Paris'. Can we make sense of this difference? Can there be rigidity without strong rigidity? Sure: Weak rigidity. So if one wants to defend Kripke's account of rigidity by appealing to radical anti-essentialism one should better also accept counterpart theory.)