Friday, November 24, 2006

Presentism and Relativity

Familiarly, the presentist faces an objection from special relativity. If presentism is true then only presently existing things exist. What is present is simultaneous with your reading this. So what exists are all and only the things that are simultaneous with your reading this just now. But what is simultaneous with your reading this just now is relative to a frame of reference. Therefore, what exists is relative to a frame of reference. But that’s nuts, so presentism is false.

What does the presentist need to do? Well, they win the game, presumably, if they can give some reason for privileging one reference frame over any other, for in that case they can claim simply that what exists is what is simultaneous with your reading of this according to the privileged reference frame. But how can they have a reason for thinking that one reference frame is privileged (without resorting to claiming that God smiles upon one and not the others)?

What we need is a truthmaker for the claim that some reference frame is privileged. Easy! Remember that to exist is to be present. So consider all the things that exist – they are all and only the present things. So surely the privileged reference frame is just that one according to which exactly these things are simultaneous. In that case the truthmaker for the fact that this is the privileged reference frame is just what makes it true that those things exist – namely, those things.

So the thought is this. Everyone in this debate agrees that there is a unique set, S, which is the set of the existing entities. (If you give up on that you don’t get to say ‘but that’s nuts’ in the original argument against presentism.) This (correct me if I’m wrong – I may be (not for the 1st time!) misunderstanding the physics) lets us single out a unique reference frame: the unique reference frame according to which exactly the members of S are simultaneous. And so, if we’ve got good reason to think that everything that exists is present then we’ve got good reason to think that this frame is the privileged reference frame. Since everything in S exists then everything in S is present; so they had better be simultaneous; so the reference frame that says they are simultaneous is obviously the privileged one.

Convinced? I imagine not. Nor am I. But what’s wrong? I’m finding it hard to put my finger on it. What more is needed from the presentist? Or what are they doing that’s illegitimate?

Monday, November 20, 2006

A question about relations

Excuse my ignorance on this topic: I might be making either a stupid mistake or an obvious point - pointers to the literature are welcome!

Consider the relational expressions ‘is a child of’ and the relation ‘is a parent of’. It seems that we shouldn’t have to admit relations corresponding to both expressions into our ontology. If we believe in the is a child of relation then it is a constituent of the state of affairs a is b’s child, which is the truthmaker both for [a is a child of b] and [b is a parent of a] – we don’t need a separate relation is a parent of that is a constituent of the state of affairs b is a’s parent which makes the latter proposition true.

So we only need one relation here, not two. And it also seems crazy to think that one of the descriptions is privileged – i.e. to say that there is a relation corresponding to ‘is a child of’ but none corresponding to ‘is a parent of’. If that were the case, how we could know which expression picked out a real relation. Distinguishing between the world where ‘is a child of’ picks out a genuine relation and ‘is a parent of’ doesn’t and the world where ‘is a parent of’ picks out a genuine relation and ‘is a child of’ doesn’t seems like a bad case of distinguishing without a difference. There is just one relation that holds between a and b, and it is appropriate to call it both the ‘being a child of’ relation and the ‘being a parent of’ relation, depending on what order we list the terms.

But if that’s right we need to rethink how we state the properties of relations. Orthodoxy has it that the is a child of relation is non-symmetric: a can bear it to b without b bearing it to a. But if the above is right then this is false: b does bear it back to a – but in the other direction!

Two options then: either we could let symmetry etc apply to descriptions of the relations rather than the relations themselves, or we could ass directionality into our ideology and say that a relation R is symmetric iff if a bears R to b in a particular direction then b bears R to a in the same direction.

I prefer the second route. Can anyone foresee any problems? Or am I missing something in the first place?

Wednesday, November 01, 2006

Abortion and 'in virtue of'

This is on the ‘values’ side of ‘metaphysical values, rather than the ‘metaphysical’; but I will talk about 'in virtue of', so I don't feel totally ashamed :-)

We are doing a reading group on abortion, and today we were reading Liz Harman’s ‘The potentiality problem’. Harman is interested in how to defend the position that says both that early term abortions are morally permissible and that harms to human babies are worse than harms to, say, cats.

If early term abortions are morally permissible (and not just because not aborting would result in some greater evil, such as the death of the mother) then it seems they are so because the embryo has no moral status. But the baby appears to have moral status, if harming it is worse than harming the cat, so we need an account of what it takes to have moral status that lets the baby in but not the embryo (and it may or may not let the cat it). Harman proposes the following principle:

Conscious: A being has moral status at t just in case it is ever conscious and it is not dead at t.

(She should add ‘and it exists at t’ I think, but let’s not quibble.)

Since I am conscious, the embryo that I was (assuming that I was a embryo) had moral status. But since an embryo which is aborted is not conscious at any time, it does not have moral status at any time, and so it is permissible to abort it.

So I’m permitted to abort this embryo because it lacks moral status, but the reason that it lacks moral status is precisely because I aborted it: had I not aborted it, it would (at least, so we can suppose) have been conscious at some time, and so would have had moral status as an embryo. So I’m permitted to do this action because of something that is only true because I do this action – I don’t like it!

Consider another case. Suppose the moral oracle (completely trustworthy on all moral issues) tells us that it’s really, really bad to utter falsehoods. So bad, in fact, that if someone utters a falsehood, it’s permissible to kill them. Now I ask you what you’re going to do tomorrow and you say ‘I’m going to the cinema’. And then I shoot you. I was perfectly justified, because you spoke falsely: you’re not going to the cinema tomorrow, because tomorrow you will be dead! But intuitively, even in the world in which uttering falsehoods is a bad punishable by death, I shouldn’t be justified in punishing you for something that was only the case because I punished you.

The worry is this. In the ‘falsity is bad’ world, the proposition [it is permissible to kill a] is true in virtue of [a told a falsehood]. But [a told a falsehood] is true in virtue of [I killed a]. So it looks like the ultimate basis for the truth of [it is permissible to kill a] is in [I killed a]. And that looks absurd: my carrying out an action shouldn’t be what makes it the case that I was permitted to carry out that action.

Likewise, for Harman, [it is permitted to abort embryo e] is true in virtue of [e is never conscious] which is in turn true in virtue of [I abort e]. So it looks like the ultimate basis for the truth of [it is permitted to abort embryo e] is in the truth of [I abort e]. And that looks totally wrong to me: my carrying out the abortion shouldn’t make it the case that I was justified in carrying out the abortion.