Saturday, March 01, 2008

Constituent vs. World Ontology

Constituent ontologists hold that objects are in some sense 'built up' from metaphysically more basic constituents (e.g. properties). Michael Loux's Principle of Constituent Identity (PCI) states that if X and Y have all the same constituents (in the same arrangement), they must be one and the same object.

But now consider our old friends, duplicates Bob1 and Bob2 in the symmetrical universe. They are qualitatively indiscernible, both intrinsically and even when we take relational properties into account. So, we might wonder, in virtue of what are they distinct? We would seem driven to posit haecceities, primitive 'thisness' or bare identity; one has the fundamental property of being Bob1 - and the other, being Bob2 - and that's what sets the two of them apart. (Robert Adams argues along these lines in his 1979 classic, 'Primitive Thisness and Primitive Identity'.)

I find this a pretty unsatisfying solution, myself. Instead, I take the possibility of "indiscernibles" to show that the whole world is metaphysically prior to its parts. We should reject PCI: there's nothing in the isolated individuals Bob1 and Bob2 that would tell you that they are two in number rather than one and the same. Instead, it is fundamental fact about the world as a whole that it contains two Bobs and not just one.

Actually, even this is not quite right, for the fundamental description of the world shouldn't engage in explicit counting. It's conceivable that there is no uniquely correct answer to the question how many objects there are in the world. For example, Ian Hacking has suggested that there may be no difference between a world containing one iron sphere in a space which curves back on itself vs. two spheres in Euclidian space. We may just have these two ways of describing one and the same possibility. At least, we shouldn't rule this out from the start. Ultimately, though, I think we can reach the conclusion that these are distinct possibilities, via the counterfactual facts (which I'm more tempted to take as primitive). In the one-sphere /curved-space world, it's a fact that if God were to turn the one sphere to gold, then any sphere accessible from this point would also be gold. But the two-sphere world is clearly different: if one were turned to gold, there would remain an iron sphere in the distance.

I do have a curious bullet to bite here nonetheless: you might initially think that there are two possible ways for God to turn an iron sphere to gold in the two-sphere world. He can turn the one sphere to gold, or else the other one. But as a Lewisian, I want to deny this. Possible worlds are fully described by qualitative description: one of two previously indiscernible iron globes is turned to gold. There is no sense to be made of another possibility exactly like this one but where the identities of the globes somehow switch or otherwise differ. (That would be to treat identity as an ontological primitive, which I'm loath to do.)


  1. If the relational properties, even the relations to god, of the two spheres are the same then god cannot convert one but not the other to gold.

  2. Ah, nice point. I wonder if it's philosophically illegitimate for me to appeal to "magic" at this point? Even if not strictly possible, it seems like we have some grasp of what would follow were it to be the case that (per impossibile) one sphere were to be altered by some unrelated, otherworldly, uncaused force.

    Alternatively, a more respectable route might be to introduce some simple physical indeterminacy (say the spheres are radioactive, with identical half-lives). Suppose it just so happens, by some astronomical fluke, that they both change (decay) at precisely identical moments. So there is no actual qualitative difference between the two spheres. Still, the indeterminacy might have resolved differently, so that one sphere decayed a bit sooner or later than it actually did. Had that been the case, the other sphere would (probably) not have followed suit (barring another astronomical fluke). So we may still be able to use these modal facts to differentiate (at least some) one-sphere from two-sphere worlds.

  3. To be honest, I think this counter-factual approach to refute Hacking is a dead-end. The whole point of the two-sphere example is to _stipulate_ a scenario where there is not - and never will be - a way to qualitatively distinguish the spheres. In saying that the spheres _might_ have been distinguishable after some fantastic magical or random event you are no longer really talking about the original scenario, since we are presumably excluding such a possibility from ever happening (even in theory) by stipulation. I guess you could insist that the spheres "might" still (under other circumstances than the ones we have stipulated) be distinguishable, but I'm not sure how this would help or even what it might mean. I have a feeling you would have to invoke "possible worlds" and "counter-parts" to the spheres and all that nonsense. (As you can tell, I'm highly skeptical of counter-factual analyses in general.)

    In any case, there is another, more fundamental, reason why this approach won't work against Hacking -- he can simply just "re-describe" the scenario again to fit his original thesis that it was indeterminate whether there was one sphere or two spheres. _You_ say that a god could come along and change one of the spheres, and that this would show that there were always two spheres there to begin with. However, Hacking could reply that, in fact, under a competing and equally valid description of what happened, the god didn't actually change one of the spheres, he just created a new one out of nothing. (Countless other "equally valid" descriptions of what happened could undoubtedly be produced at will.)

    Although I don't think Hacking's position is susceptible to counter-factual arguments, I by no means find it convincing. In fact, I think it's completely incoherent - he is, essentially, a pretty radical relativist - but I won't argue that now (that's what I wrote about in my writing sample for grad school!).


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