Wednesday, January 15, 2014

The Cosmological Argument and the Multiverse

(Slightly revised in light comments)

Two questions that contingency arguments aim to answer are:
Contingent Particularity: Why does this particular universe exist (with its particular set of particles, history, laws of nature, etc.), and not some other? 
Contingent Existence: Why does the universe exist at all, rather than just nothing?
Contingent Particularity is supposed to get at least some of its force from our supposed modal intuition that there could've been a different universe (different particles, history, laws of nature, etc.), and Contingent Existence is supposed to get at least some of its force from our supposed modal intuition that there could've been no physical universe at all.

Here I'd like to set aside Contingent Existence (at least until the end. See below), and raise a quick point about Contingent Particularity. It's this: Unlike contemporary discussion of the fine-tuning argument, much of the discussion of Contingent Particularity continues to assume that our particular universe is the only one that exists[1], and that ours is not just one universe in a multiverse -- in particular, one in which all possible universes exist. But so long as such a multiverse is an epistemic possibility, there is a corresponding epistemically possible explanation for the particularity of our universe in terms of the causal mechanisms of the multiverse. And of course our modal intuitions about how our particular universe[2] could've been different aren't sufficiently strong pieces of evidence that all physical reality's particularity is objectionably contingent. 

Objection 1: Theism is a much simpler explanation of Contingent Particularity than other hypotheses (e.g. other naturalistic hypotheses). Therefore, theism is a better explanation. 

Reply: Not so fast. As with the dialectic re: the fine tuning argument vs. the multiverse hypothesis, this isn't so clear.  For the objector seems to falsely assume that there is only one relevant kind of theoretical parsimony, viz., quantitative parsimony (i.e., the explanation postulates fewer entities). However, as David Lewis has taught us, another type is qualitative parsimony (i.e.,the explanation postulates fewer kinds of entities). And while the theistic hypothesis is a much more quantitatively parsimonious explanation of the data (it explains all of the data in terms of just one entity, viz., a god),our multiverse hypothesis is a more qualitatively parsimonious explanation of the data (since it explains all of the data solely in terms of one kind of entity, viz., matter-energy). And it's not clear which type of theoretical parsimony is more important here.

Objection 2: Such a hypothesis just pushes the Contingent Particularity question back a step. For the question now becomes: why this particular multiverse, and not some other (for example, one with fewer universes, or with a fewer range of laws or constants)?

Reply: Our modal intuitions are considerably less assured when we start talking about alternative multiverses -- especially if they go beyond the reach of even our most rarified and speculative scientific theorizing. I don't think the theist will want to take such a freewheeling approach to modalizing, as it's then hard to know how to screen out similarly freewheeling modal judgements about the particularity of God ("Why this god, and not some other?").[3]  

Objection 3: Such a hypothesis makes it puzzling why such a multiverse might exist at all (if it does exist), rather than just nothing.

Reply: That's to change the subject from Contingent Particularity to Contingent Existence. In any case, our modal intuitions about Contingent Existence are much more dubious than those about Contingent Particularity. For we have good scientific theories that entail that the universe could've had different laws and/or constants, whereas we have no comparable evidence-sensitive theory to support our modal intuitions about the possible non-existence of all matter-energy. At best, our modal intuitions about the possible non-existence of all matter-energy are on a par with our modal intuitions about the possible non-existence of God.

The upshot seems to be that multiverse hypotheses might pose as much of a problem for contingency arguments as they do for design arguments. 

--------------------------
[1] Timothy O'Connor is perhaps the most obvious exception. Derek Parfit might be another.
[2] Or (to handle Kripkean origin essentialist intuitions) some suitable surrogate(s) of our universe.
[3] One might appeal to an ontological argument at this point, but there are even fewer who are convinced by ontological arguments than cosmological arguments from contingency.  In any case, the cosmological argument would be superflous if we had such an argument at hand, and the contingency argument would fail as a successful independent argument for God's existence if the persuasiveness of the former depended on the latter. 

5 comments:

Rayndeon said...

Can't one reiterate the same contingency concern at the level of the multiverse e.g. why this multiverse, rather than some other? For instance, suppose there are 10^500 universes. Why not 10^499 or some other value? And furthermore, even if there are an infinity of universes with different physical parameters, presumably, they all are subject to similar laws. Why that set of laws rather than some other set of laws?

exapologist said...

Hi Rayndeon,

Good questions. The sort of multiverse I have in mind is one in which all possible universes exist, so that all possible laws/constants/histories exist. As you point out, one might reply that there could've been some other multiverse, but then I think our modal intuitions get murky at that point, such that they're on a par with our modal judgements about God (why this god, and not some other?). It therefore seems to me that as with the fine-tuning argument, multiverse hypotheses act as a significant counterweight to the force of contingency arguments.

Best,
EA

Angra Mainyu said...

Hi, EA,

Nice point about qualitative vs. quantitative parsimony.

On the issue of contingent particularity, when you say we have good scientific theories that entail that the universe could have had different laws and/or constants, what kind of theory do you have in mind?

I'm asking because I'm not sure there are theories that entail the "universe" that could have had different laws and/or constants would be the universe in the sense of the word "universe" that would be relevant in the context of a contingency argument.

I'm not an expert on those theories, but for example, let's say that theory T1 posits some basic laws and something (the "thing" might be a multiverse, or some kind of older "universe" in some sense, or some sort of quantum state, or whatever it is), and from that situation (given those basic laws, etc.), then a universe like ours could have emerged, but also a different universe (e.g., different forces) could have emerged as well.

Then, a theory like T1 does not entail that the basic constants, laws, etc., of the larger (and/or older) realm could have been different.

Rather, it seems to me that it entails that within that larger (and/or older) realm, something other than our universe (in a more limited sense of "universe") could have emerged.
But in that case, there is not implication of the contingent particularity of all of what would count as "universe" in the context of a contingency argument. In particular, the theist arguing from contingency (or rather, for the contingency of the universe) holds that even those basic laws (or whatever T1 posits as basic, and from which it derives that there could have been a different universe, in a limited sense of "universe") are contingent and could have been different, but that's not entailed by T1.

In fact, in the context of T1, the contingency of what might be called a "universe" in a more limited sense would require an explanation as to why, within T1, this universe emerged rather than another one. But that seems to me akin to asking why, within an evolutionary process that respects certain laws, etc., flies emerged. It's a scientific question, but not one that would help the theist arguing from contingency, as far as I can tell.

Rayndeon said...

EA,

Are you conceiving of this multiverse will all possible laws, initial conditions, physical parameters, etc as basically being a necessary being? If not, then is that sufficiently answering the contingency worry? If this multiverse you're thinking of turns out to be contingent, then there will be a dis-analogy between the multiverse and God, as the latter is taken to be necessarily existent in this case.

What you say in your most recent reply sounds very similar to modal realism. Modal realism in a sense could be considered a type of modal collapse to an actualist - as van Inwagen would say, the actual world just turned out to be a lot, lot richer than we had originally thought. But it does seem to amount to a type of necessary being, at least if we think about possibility and necessity in terms of standard actualist metaphysics.

However, you end up saying that you are imagining a world in which every possible combination of laws, histories, and parameters exist in some spatiotemporal aggregrate. The worry becomes that we've emptied the idea of "all possible laws/histories/constants exist" to "all existing laws/histories/constants exist," which is trivial and vacuous - since the possible is just the actual qua actualism. And on modal realism, to say that such and such is possible is to say that there is some maximal spatiotemporal aggregrate at which it obtains. And to speak of a combination of laws, history, and constants seems to be nothing more than some maximal spatiotemporal aggregrate. So, again the worry seems to be that we reduce "All possible laws, histories, and constants in combination exist in some universe" to "All laws, histories, and constants that exist in some universe exist in some universe." That too seems empty of substantive content. How are we to express the richness of the multiverse you seem to be conceiving of?

It's possible I might be making too much of this issue. But I'm wondering how to countenance the structure of the multiverse you're thinking of. Maybe instead of merely "possible," we could use something like logical consistency? But then the worry is whether logical consistency is rich enough to give the structure you want. We might perhaps broaden it to the class of conceptual possibility - what is consistent with the conceptual truths e.g. no bachelors are married, there are no prime ministers that are prime numbers, etc. Maybe that does the trick - I'm not sure. I have other worries, but let me know what you think of the above.

exapologist said...

Are you conceiving of this multiverse will all possible laws, initial conditions, physical parameters, etc as basically being a necessary being? If not, then is that sufficiently answering the contingency worry? If this multiverse you're thinking of turns out to be contingent, then there will be a dis-analogy between the multiverse and God, as the latter is taken to be necessarily existent in this case.

Hi Rayndeon,

Yes, that's the idea -- I'm postulating that such a multiverse is a metaphysically necessary being, as a rival to God in that role. As I tried to indicate in my post, I think our modal intuitions run out of gas when it comes to evaluating the modal status of ontologically fundamental, metaphysically necessary concreta, such as God and such a multiverse. If either such being is metaphysically necessary, it doesn't wear its necessity on its sleeve, as it were. Absent a persuasive ontological argument, the non-existence of both god and the multiverse seem conceivable. So the conceivable non-existence of a multiverse is a problem for the latter's candidacy as a necessary being only if it's a problem for the former's candidacy. So again, it seems to me that the multiverse hypothesis is just as much of a problem for the contingency argument as it is for the fine-tuning argument.

Best,
EA