## Sunday, November 29, 2009

### Is My 3-and-1/2-Year-Old Daughter A Modal Realist?

This morning over breakfast my 3-and-1/2-yr-old daughter told me 'Golden shoes do not exist in this world'. 'Where do they exist then?' I asked. 'In another world' she replied with the tone of someone who is saying something obvious. I always thought modal realism was semantically revisionary but apparently this does not apply to the pre-school crowd! :-) (I still hope she just believes in island universes, though!)

## Friday, November 27, 2009

### A deflationary theory of diachronic identity

Thanks, Gabriele, for inviting me to this blog.

First, the easy version of the deflationary account. Here is a question about diachronic identity: What makes it be the case that:

1. Some F0 at t0 is diachronically identical with some F1 at t1.

1. There exists an x such that x is an F0 at t0 and x is an F1 at t1.

Observe that (2) does not make use of "diachronic identity" in its statement. Moreover, all of the conceptual ingredients that (2) uses are ones that any substantive account of diachronic identity (the memory or bodily continuity theories in the case of persons are paradigms) will also have to use in analyzing (1): being an F0 at t0, being an F1 at t1, quantification and conjunction (I have a hard time imagining any substantive account of diachronic identity that somewhere doesn't presuppose conjunction!) So, (2) is simpler, and if it is conceptually circular, so is any substantive account.

Now, the somewhat harder version, the question of analyzing diachronic identity wffs. Question: What makes it be the case that:

1. x at t0 is diachronically identical with y at t1.

1. x exists at t0 and x exists at t1 and y exists at t1 and x is synchronously identical at t1 with y.

Since we all need synchronous identity, and it does not seem to be posterior to diachronic identity, it seems fair to presuppose it in an account of diachronic identity. The result seems to be an account of diachronic identity much simpler than any substantive account.

If one is worried that "x exists at t" presupposes diachronic identity, consider this. What is it to exist at t? Here are some standard proposals:

• Presentism: At t: x exists.

• Perdurantism: a part of x is located within the spacelike hypersurface t.

• Eternalist endurantism: x is wholly located within the spacelike hypersurface t.

None of these proposals seem to presuppose diachronic identity. Now, the last two proposals require an analysis of being located or wholly located in a region R. But this could be just a matter of instantiating a primitive located-at relation to R, or a matter of having R if regions just are properties (I am fond of--though I do not endorse--the proposal that regions are properties, with containment being entailment, and that to be in a region is to have the region as a property), or a matter of being appropriately related to other entities by the nexus of spatiotemporal relations.

In any case, substantive accounts of diachronic identity do not clarify what it is to be located in a region of spacetime or what it is to exist at t. Substantive accounts of diachronic identity explain what it is for an object that is located in one region to exist in another region, but that still doesn't explain what it was for the object to be located in the first region. In fact, there is something really weird about substantive accounts of diachronic identity here. It would be very strange to claim to have a good account of what it is for a person who is queen of country x to also be queen of country y (for general non-identical x and y) without that account also being an account of what it is for a person to be queen of x (for a general x). Surely we all need an account of what it is for a person to be a queen of x, and once we have that, the account of what it is for the queen of country x to also be the queen of country y is just a matter of applying that account twice (and using synchronic identity to take care of the definite articles). But like the queen-identity theorist, the substantive diachronic identity theorist has an account of what it is for, say, a person who occupies R1 to also occupy R2, without having an account of what it is to occupy R1. And once we have an account of what it is to occupy R1, we get for free an account of what it is to occupy R1 and R2, at least if we have synchronic identity.

Maybe the simplest way to summarize the deflationary account is this. It is no more mysterious how it is that x at t0 is identical with y at t1 than it is how it is that x who is the Queen of England is identical with y who is the Queen of Canada.

However, the above arguments presupposed that we're dealing with entities facts about which do not wholly reduce to facts about some other entities. In the case of wholly reducible entities, my arguments fail. The reason for that is that in the case of a wholly reducible entity, what it is to exist at t will be reducible to facts about some other class of entities. For instance, for a reducible x to exist at t will not be a matter of x's instantiating some primitive located-at relations. In that case, the conceptual baggage of "exists at t" might be the same as the conceptual baggage of the substantive account of diachronic identity, and so the deflationary account may be incorrect. (I think of wholly reducible entities as akin to wholly stipulative meanings. In the case of words with wholly stipulative meanings, we might not expect deflationary accounts of truth and meaning to apply--we might want the stipulations to be expanded out, like abbreviations, before the deflationary account is applied.)

If I am right, then someone giving a substantive account of what diachronic identity for Ks consists in is committed to Ks being reducible.

## Thursday, November 26, 2009

### Faculty Move: Schaffer from ANU to Rutgers (in 2011)

In case there is anyone out there who hasn't heard the news yet, Jonathan Schaffer has accepted an offer at the Professor from Rutgers and will be moving there from ANU in 2011. The temptation to leiter a bit about the significance of this move is really strong but, for the readers' sake, I'll resist it and just say: 'Congratulations, Jonathan (and Rutgers)!!!'

## Wednesday, November 25, 2009

### Constitution and Strong Coincidence

I was rereading Ryan Wasserman's 'The Standard Objection to the Standard Account' for a seminar on material constitution that I'm teaching this term. In it, Wasserman considers a number of "mereological" solutions to the "standard objection" (i.e. since Lump and David share all of their microphysical parts, there is nothing to explain their difference in kind and de re modal and temporal properties). Wasserman considers three responses to that objection: the no coincidence response (Lump and David share no parts), the weak coincidence response (Lump and David weakly coincide, which essentially boils down to the fact that all parts of Lump are parts of David but some parts of David (e.g. its arm) are not part of Lump), and the strong coincidence response (Lump and David strongly coincide share all their (material) parts at every time they both exist). While I think Wasserman's case against the first two views is strong, I'm not persuaded by his case for the third view. (In fact, I'm not even sure I understand what his proposal exactly is.)

The strong coincidence response (SCR) seems to be committed to the following claims:
1. For any time t, if Lump and David exist at t, they wholly exist at t.
2. For any time t, if Lump and David exist at t, they strongly materially coincide at t (i.e. every (material?) part of Lump at t is a part of David at t and every part of David at t is a (material?) part of Lump at t.)
3. For any time t, if Lump and David exist at t, they spatially coincide at t (i.e. every spatial part of Lump at t is a part of David at t and every spatial part of David at t is a part of Lump at t.)

So, one could wonder (at least I do) how can David and Lump differ in their parts given (1)-(3)? Since I'm not quite sure I understand Wasserman's answer, I'll let him do the talking now (I only divide the different claims and label them for the sake of the discussion):

[(a)][Both the defender of the standard account and the defender of the doctrine of temporal parts] will agree that David is a temporal part of Lump during the interval from t2 [when David came into existence] to t3 [when David and Lump ceased to exist]. For David exists only during that interval, David is a part of Lump during that interval and David overlaps during that interval everything that is a part of Lump during that interval.
[(b)] Moreover, both parties will agree that David is a proper temporal part of Lump during the interval in question since David is not identical to Lump.
[(c)]The two parties will not agree on everything, of course. Most importantly, the temporal parts theorist will assert, and the proponent of the standard account will deny, that Lump has temporal parts (during the interval from t1 [when Lump came into existence] to t2) that David lacks.
[(d)] Still, given that David is a proper temporal part of Lump, there must be some sense in which these two objects differ in parts.
[(e)] Indeed there is: Lump has spatial parts during the interval from t1 to t2 that David lacks.
I find it very hard to see how (a) and (even harder) (b) can be true. In fact, I can't see any good reason for the constitutionalist qua endurantist to hold that David is a temporal part of Lump between t2 and t3 let alone a proper temporal part of it. If one believes that Lump and David wholly exist at every time at which they exist, they would seem to have to believe that, at most, David and Lump can only have improper temporal parts at every time at which they exist (At t, if Lump exists, it is its only temporal part) but I can't see any plausible way to think that one can be a proper temporal part of the other (David can be a proper temporal part of Lump only if there are temporal parts of Lump that are not temporal parts of David, but since, given (1), it would seem that neither Lump nor David has (proper) temporal parts, I can't see how the latter can be a proper temporal part of the former).

I find it even harder to see how (b) can be true given (c). If the constitutionalist qua endurantist denies that Lump has temporal parts David lacks how can the latter be a proper temporal part of the former? According to Wasserman's (e), it would seem it can be so by virtue of Lump's having spatial parts between t1 and t2 that David does not have (after all, David doesn't exist during that period!).

Okay, so, suppose that you and Wasserman are standing in front of Lump and David and you ask 'But how can Lump and David have different kind, de re temporal and de re modal properties right now even if right now they are sharing all of their parts and their only parts are parts that exist right now?' I guess Wasserman's answer would be: 'Well, they do because they did not share all of their parts yesterday when David did not exist' But, at most this can explain why bakc then it was posssible for them to have different properties but not how it's possible now when the two share all of their parts (according to (2)).

I guess I'm missing something terribly obvious. Can anyone help me see what that something is?

(Let me mention a few other things Wasserman says that I find very puzzling:

Wasserman suggests that the standard objection applies not only to constitutionalism but also to fourdimensionalism and to the view that my hand is a spatial part of myself. But how can that be the case if the standard objection is predicated on the two objects sharing all of their parts? (of course the part of me that spatially coincides with my hand shares all of the parts with my hand (it is my hand after all!) but I don't)

And even if the standard objection applies to those views as well wouldn't that be a reason for those who hold those views to worry rather than a reason for the constitutionalist to feel relieved given that there are other views (most notably, nihilism) that are immune to that objection?

Finally, Wasserman seems to assume that a difference in temporal or spatial parts can explain a difference in kind, but I don't see any good reason to think so. There seems to be plenty of objects that differ in spatial and temporal parts without differing in kind and the reason why I am a human being and my hand is not is presumably not that I don't spatially coincide with my hands (althugh presumably it is a necessary condition for my being human).)

## Saturday, November 14, 2009

### Schliesser on Metaphysics and "Scientifically Informed" Philosophy

Eric Schliesser has a post at It's Only A Theory in which he explains what he "find[s] problematic about mainstream contemporary metaphysics from the point of view of philosophy that wishes to be scientifically informed and open to learning from and be surprised by science".

I thought some readers of this blog might be interested in reading what he has to say and chime in!