One objection you sometimes hear against Lewis’s modal realism (from van Inwagen, Chihara, Jubien, among others) is that what goes on at concrete spacetimes is irrelevant to what is necessary or merely possible. The objection, I take it, is this. We can grant for the sake of argument that there are the many cosmoi Lewis would have us believe in. But even on the assumption that there are these things, it’s not clear what they would have to do with modality. When we think of what is merely possible we are thinking of what could have been the case but isn’t (that’s the work the ‘merely’ is doing); but Lewis tells us that the merely possible is the case, it just isn’t the case here – at the sub-portion of all that there is that is spatio-temporally related to us: the portion that Lewis calls ‘actuality’.
The gist of the modal irrelevance objection, I take it, is that to say that something is merely possible demands that it not be the case – not simply that it not be the case in our surroundings, but that it not be the case at all. If Lewis is right about what there is then, the thought goes, it simply turns out that what is actually the case is a lot more complex than we thought. Actuality, the thought goes, is everything that (unrestrictedly) is the case: if there are talking donkeys that aren’t spatio-temporally related to me then there are actually talking donkeys that aren’t spatio-temporally related to me. Lewis can choose to use the term ‘actually’ as he wishes, of course; likewise with the terms ‘possible’ and ‘necessary’. But nevertheless the point remains that, using those words as we use them, Lewis is asking us to accept that actuality is a lot bigger than we supposed; he’s not asking us to accept the existence of the merely possible. The latter request is unfulfillable: you can’t accept the existence of the merely possible, because if something exists then it’s not merely possible – it’s actual.
Does anyone raise the analogous objection against eternalism? We can imagine someone arguing as follows:
“Just as I have the intuition that to say something is merely possible demands that it not be the case, so I have the intuition that to say that something is merely past or future demands that it not be the case. And yet the eternalist says that past and future events are the case: they’re not the case in my surroundings – the portion of what there is that the eternalist calls ‘the present’ – but they are the case nevertheless. But just as I can’t see why the presence of talking donkeys would result in it being merely possible that there are talking donkeys as opposed to it being actual just because the talking donkeys aren’t spatio-temporally related to me, so I can’t see why the presence of dinosaurs would result in it being the case that there were or will be dinosaurs as opposed to it being the case that there are presently dinosaurs just because the dinosaurs happen to be in a direction I can’t point!”
The objections are totally analogous. Just as the modal irrelevance objection says that you can’t have an ontology of the non-actual, you can only make actuality more complicated, so the temporal irrelevance objection says you can’t have an ontology of the non-present, you can only make the present more complicated.
The temporal irrelevance objection claims that if it was true that there are dinosaurs but that there are not presently dinosaurs then this demands that there are no dinosaurs; likewise, if it will be true that there are Martian colonies but that there are not presently Martian colonies then this demands that there are no Martian colonies. The eternalist will claim that something’s being merely past or future demands not that it not be the case, but only that it not be the case presently. But that is, seemingly, no more convincing than Lewis’s claim that something’s being merely possible demands only that it not be the case actually. The actualist can agree that something’s being merely possible demands only that it not actually be the case provided that actuality is understood as encompassing everything (unrestrictedly). Likewise, the presentist can agree that something’s being merely past or future demands only that it not presently be the case provided that the present is understood as encompassing everything (unrestrictedly).
So, here are some questions:
(1) Has anyone made the temporal irrelevance objection, or anything like it, in the literature?
(2) Do the modal irrelevance and the temporal irrelevance objections really stand or fall together or is there some disanalogy between them?
(3) If they are analogous, is this so much the worse for the eternalist or so much the worse for the modal irrelevance objection?
(2) is the question I’m most interested in. I guess one reason you might think that the temporal irrelevance objection is worse off is that the eternalist can point to certain relations between the dinosaurs and us that justify our claim that the dinosaurs existed before us, whereas there is nothing analogous the Lewisian can do w.r.t. the talking donkeys.
Those relations would, presumably, be causal relations. But will that help? Can’t the presentist who is impressed by the temporal irrelevance objection simply reply that if some of the things that there are stand in causal relations to some of the other things that there are then – unless we have independent reason to think that the former things are past entities and the latter things present entities – we should conclude that causal relations can hold between presently existing entities, not that there is in fact non-present ontology?
Anyway, those are my ramblings for today. Thoughts?
In other news, I see that David Cameron has proposed that the salaries of GPs be tied to the health of their patients and patient satisfaction. Ignoring the obvious problems with such a stupid idea (such as it making it even harder to get GPs to work in deprived areas), I wonder if he’s going to take the obvious next step: to link MP’s salaries to the general level of Eudaimonia and the approval ratings of them by their constituents. Somehow, I doubt it.