## Friday, September 28, 2007

### Properties as sets of (actual) individuals

One benefit of admitting the existence of possibilia, says Lewis, is the identification of properties with sets of possibilia. I've always been confused as to why this is meant to be better than the actualist saying that proeprties are sets of their instances.

Lewis says, "The usual objection to taking properties as sets is that different properties may happen to be coextensive. . . the property of having a heart is different from the property of having a kidney, since there could have been a creature with a heart but no kidneys." And this is usually the reason I'm given when I ask this question.

But the 'since' is no good! The fact that there could have been a creature with a heart but no kidneys shows only that the property of being a renate might not have been the property of being a cordate. That only tells us that the properties are actually distinct, and hence that the properties aren't actually identical to their actual instances, if we accept the (necessity of) the necessity of non-distinctness. But Lewis *doesn't* accept that, due to his acceptance of counterpart theory.

Assuming contingent identity in general is not incoherent, what would be wrong with someone holding that being a cordate *is* identical to being a renate, but only contingently so? On this view, something might have had being a cordate and lacked being a renate because the actually identical properties might have been distinct. Whenever Lewis holds that two distinct properties are accidentally coextensive this theorist holds that they are contingently identical; properties that Lewis identifies, this theorist claims to be necessarily identical. Would anything go wrong with this?

You might object to the proposal on the grounds that, even if contingent identity in general is okay, it's not okay for sets to be contingently identical. Why? Because sets have their members essentially and because the axiom of extensionality is necessary. Those two claims entail that identical sets are necessarily identical. (Proof: if S and S* are identical they share their members. Given the essentiality of membership they share their members in all worlds. So given the necessity of extensionality they are identical in all worlds.) But I don't find this that convincing from the perspective of the counterpart theorist. I think the counterpart theorist should hold that whether sets have their members essentially is a context-sensitive matter, just as it is a context-sensitive matter whether or not I am essentially human. When we specify a set extensionally - 'the set of a, b, and c' - it's natural to suppose we invoke a context whereby nothing gets to be a counterpart of that set unless its members are the counterparts of a, b and c (what we say if one of a, b or c has multiple counterparts at a world is going to get tricky). But when we specify a set intensionally - 'the set of the Fs' - it's natural to suppose that the counterpart of this set at a world is the set of the things at that world that are F. It doesn't seem objectionable to me, then, to say that 'the set of the cordates' and 'the set of the renates' are contingently identical which, on the current proposal, is just what it is for the proeprties being a cordate and being a renate to be contingently identical. Being such that 2+2=4 and being such that everything is self-identical, on the other hand, will be necessarily identical, because at every world the set of things that are such that 2+2=4 is identical to the set of things that are such thateverything is self-identical - namely, it is the set containing everything at that world.

I'd be interested to hear reasons for not going this way.

## Monday, September 24, 2007

### From Ockham to nihilism?

Some thoughts I've been having as a result of a conversation with Daniel Nolan:

Does Ockham’s razor give us reason to be mereological nihilists? Ockham’s razor tells us not to multiply entities beyond necessity. A popular argument for nihilism is that mereologically complex entities don’t do anything simples arranged a certain way wouldn’t do on their own. That’s why Merricks, for example, believes that the only complex entities are conscious ones: he thinks that consciousness is a property that can’t be had collectively by a plurality of simples, so there needs to be a conscious mereologically complex object; but unconscious complex entities like tables and chairs wouldn’t do anything simples-arranged table/chair-wise on their own wouldn’t do, and so it would be a violation of Ockham’s razor to admit their existence.

But is it true that tables don’t do anything that collections of simples arranged table-wise wouldn’t do on their own? One thing I think my table does is stop my glass – which is, I think, sitting on it – from falling to the floor. If there were no table would the collection of simples arranged table-wise do this on their own? You might think not, because the closest possible world in which the simples arranged table-wise exist but the table doesn’t is one in which the glass also doesn’t exist, and only the simples arranged glass-wise are being kept from falling to the floor (or, rather, the simples arranged floor-wise).

An assumption here in the above is that a nihilistic world is closer to our world (assuming nihilism is in fact false) than a world where some of the collections that would compose in our world compose but some don’t. Why believe that? Well if the simples arranged table-wise don’t compose anything but the simples arranged glass-wise do then it would seem to be an entirely arbitrary matter whether a collection of simples compose something. We’d like to be able to explain why some collection composes or fails to compose some thing by saying something like ‘they compose something because every collection composes something’, or ‘they don’t compose anything, but no plurality of things ever composes some thing’, or ‘they compose something because they’re close enough together’, or some such thing. There doesn’t seem to be any natural condition that the parts of the glass meet but the simples arranged table-wise don’t meet, however; so in the world in question, composition seems to be an arbitrary affair. The nihilistic world – despite being unlike our world in many ways – is like ours (or like we hope ours is) in that composition occurs or fails to occur systematically: there is intra-world supervenience of the composition facts on the non-compositional facts. Perhaps that’s enough to give some reason for thinking that the nihilist world is closer to ours than the ‘mixed-world’. In any case, let us grant the assumption for the sake of argument.

Does it follow from that assumption that there is no Ockham’s razor argument for nihilism? The nihilist might object that the argument is question-begging, since it assumes that some of the work that is to be accounted for is the work of keeping the glass from falling to the ground. We should, the nihilist might counter, start from a neutral ground, in which case the datum to be accounted for can only be described as that the table-like simples are keeping the glass-like simples from falling to the ground-like simples.

But wouldn’t that be equally question begging on the part of the nihilist? Why shouldn’t I appeal to the table’s ability to stop the glass itself – not just the simples arranged glass-wise – from falling to the ground as something that the table itself – not just the simples arranged table-wise – does? After all, I think it’s true that there is a glass on a table and that it would fall to the ground were the table not there. Isn’t the nihilist’s insistence that I only admit objects to explain facts that the nihilist accepts as true simply stacking the deck in favour of nihilism?

The nihilist might question my reason for believing that to be true. Fair enough – obviously I should have a reason for taking as true the truths I want my ontology to ground. Here’s my reason then: I can see the glass on the table, and by induction I know that were the table not there the glass would fall to the floor. The nihilist denies that this is what I see, of course; but why let her set the debate by accepting her description of the phenomena rather that mine?

Anti-nihilism, one might think, is the default view. We have to be argued away from a belief in tables in chairs towards a nihilist ontology; we don’t have to be argued from a nihilist ontology towards a belief in tables and chairs. The burden of proof is on the nihilist, not the compositionalist. If that’s right then it’s perfectly appropriate for me to take as a datum that the glass is held up by the table and to try to explain it. I grant that if one can explain that datum with a nihilist ontology then there’s an Ockham’s razor argument for nihilism over compositionalism; but the fact that one could explain a nihilistic paraphrase of that datum with a nihilist ontology is neither here nor there. Since it is doubtful that a nihilist ontology can explain why my glass is held up by the table, it’s not obvious that there’s even a pro tanto reason for nihilism by way of Ockham’s razor.

## Tuesday, September 18, 2007

### Titles in search of a paper

Aidan has a funny post about good and bad puns in paper titles. This prompted me to think of some potential papers yet to find an author. I came up with:

“Trouble up mill!” (A paper pointing out difficulties for the harm principle – probably only funny if you know anything about Yorkshire – or watched enough Monty Python.)

“You can’t get a nought from an is.” (An paper arguing against reifying absences.)

“Does ought imply Kamm?” (a paper on Frances Kamm and moral obligation.)

“Frege’s conception of women as objects.” (A paper on neo-Logicist feminism.)

“There can be only one.” (Monism meets Highlander.)

Any others?

## Wednesday, September 12, 2007

### Society of Solipsists

This is quite funny.