Physicist Sean Carroll on God and Modern Physics
September 12, 2012 — 15:50

Author: Kenny Pearce  Category: Existence of God Links  Tags: , , , , ,   Comments: 10

I want to draw Prosblogion readers’ attention to a very interesting paper by CalTech physicist Sean Carroll, “Does the Universe Need God?” (hat tip: ex-apologist). The article is to be published in The Blackwell Companion to Science and Christianity. The article is a model of constructive dialog between philosophy and physics. Carroll shows engagement with the major philosophical arguments under discussion, and does not come off as condescending or dismissive. He also provides concise and helpful summaries of the relevant physics. Additionally, the article shows an admirable degree of epistemic humility, noting that there are many unsolved problems in physics and that our theory of the early universe is not polished and completed, while still arguing that we have enough information to shape our views on origins. The article is quite readable, and would certainly be helpful for students.
Let me make a few remarks on Carroll’s actual arguments and positions. Near the beginning of the article, Carroll quickly summarizes the possible responses to ‘first cause’-type cosmological arguments. It seems to me that he is on firm ground here: it is unclear whether there even is a first moment, and if there is then it is not clear that it even makes sense to ask what caused the state of the universe in that first moment, if we are looking for another cause in the series of causes. Besides (although Carroll does not make this point), classical philosophical theology does not conceive of God as one more cause in the series of causes. So the first cause argument isn’t really going anywhere. I myself think that insofar as the first cause argument is tempting, this is because it gets confused with the argument from contingency: people aren’t really asking what caused the first state of the universe, they are asking why was the state of the universe as it was, and it’s quite clear that, if there really is a first moment, then the answer to that question could not possibly be another ordinary physical cause: either it has no answer, or it has an answer of a very different sort.
Carroll next offers detailed criticism of the ‘fine-tuning’ argument. The main point Carroll makes here is that the multiverse hypotheses which physicists take seriously are not just introducing enormous numbers of universes as ad hoc posits for the purpose of getting rid of fine-tuning. One sort of multiverse, for instance, falls neatly out of inflationary cosmology, which is a well-verified physical theory. (Brian Greene’s latest book, The Hidden Reality, surveys the range of multiverse theories and the different degrees of evidence for them.) So to say that the multiverse is excessively complex and so should be rejected is to misunderstand the sort of simplicity we should be looking for. Now, Carroll runs over some distinctions between different multiverse theories here; my understanding on the basis of Greene’s book is that the multiverse theories that do the most to eliminate fine-tuning are the least well-supported and widely accepted among those on offer, and that it is true of some of these theories that their main attraction for their adherents is to get rid of fine-tuning. I’m not, however, convinced that that’s bad: apparent fine-tuning is one of the things physicists try to explain. If a particular multiverse hypothesis provides a simple explanation of a particular apparent fine-tuning, then good for it. And I agree with Carroll on what simplicity should mean here. Leibniz said that God would create the world which was simplest in principles and most varied in phenomena (see, e.g., DM 5). This is the kind of simplicity that matters here: simplicity of the fundamental principles. If they generate many and varied phenomena (e.g. an enormous variety of universes), this is no stroke against them. Again, point Carroll.
Near the end of the article, Carroll does come to discuss the argument from contingency. Unfortunately, he does not, in my view, take it as seriously as it deserves. He essentially says that, although we ought always to look for explanations with respect to things in the universe, there can be no such explanation of the universe as a whole or its most basic laws. In The Principle of Sufficient Reason: A Reassessment Alexander Pruss makes the case that the PSR cannot be restricted in any non-ad hoc way without undermining the assumptions of explainability made in ordinary scientific practice. Carroll ultimately simply pronounces that “There is no reason, within anything we currently understand about the ultimate structure of reality, to think of the existence and persistence and regularity of the universe as things that require external explanation.” He doesn’t give an adequate account of exactly what restrictions he is placing on explainability, or how they are justified. He seems to be supposing that what things we take to be in need of explanation depends on our physical theory. The trouble is, our practices with respect to explanation must be at least partly a priori in character: we have to start looking for explanations before we’ve got any explanations. Furthermore, Carroll’s example, that in modern physics there is no need for Aristotle’s Prime Mover because of the Law of Inertia, neglects the fact that an appeal to the Law of Inertia is itself an explanation of why objects continue in their state of motion. It is not that we’ve discovered that these things don’t need explanation, but rather that we’ve discovered that the correct explanation is of a very different sort from what Aristotle had in mind.
The argument from contingency, however, takes God outside the realm of physics. God here provides a different kind of explanation to a different kind of problem. This, to my mind, is one of the key reasons why the argument from contingency and the ontological argument are far more credible than either the first cause argument or the fine-tuning argument. That theism is not a credible physical theory is transparently obvious. Whether it is a credible metaphysical theory is another question entirely. I also note that the standards of credibility for metaphyiscal theories are quite lax compared to those for physical theories. Might theism enjoy the same level of (objective) support as quantum field theory? Not a chance. Might it enjoy the same level of (objective) support as (say) our best theories of universals? On this latter point I would say, it can, and it does.

Comments:
  • Interesting stuff!
    One issue I think deserve some comments is that part of his argument depends on “God of the Gap”-thinking being the norm or part of some extremely important arguments in Theistic Natural philosophy. E.g.
    “Over the past five hundred years, the progress of science has worked to strip away God’s roles in the world. He isn’t needed to keep things moving, or to develop the complexity of living creatures, or to account for the existence of the universe.”
    and
    “We can’t be sure that a fully naturalist understanding of cosmology is forthcoming, but at the same time there is no reason to doubt it. Two thousand years ago, it was perfectly reasonable to invoke God as an explanation for natural phenomena; now, we can do much better.”
    As I can’t quite see this has been the case, I wonder why he is arguing in this way? Or does the rest of the book show he is right?

    September 13, 2012 — 2:42
  • Kenny Pearce

    Yes, this claim that theistic belief used to be rational but isn’t any more is a common, and I think quite misguided, one. It seems to me that no arguments that were any good in the first place have been undermined by the progress of science. The progress of science has, however, made it more obvious that certain arguments are bad, but those arguments were bad all along. (I’m thinking, e.g., of naive ‘God of the gaps’ arguments.) Now, I think the fine-tuning argument is basically just a gap argument, despite its proponents’ claims to the contrary. That is, the fine-tuning argument says ‘there are things that natural science tries to explain that it hasn’t been able to explain so far, so we should posit God as the explanation.’ The fact that the things in need of explanation are the values of the constants rather than some particular natural events is, in my view, beside the point.
    On the other hand, not all theistic arguments are like this, and that’s a point Carroll doesn’t seem adequately to recognize. This is part of his giving short shrift to the argument from contingency.

    September 13, 2012 — 10:23
  • “Two thousand years ago, it was perfectly reasonable to invoke God as an explanation for natural phenomena; now, we can do much better.”
    Suppose that theism is true. Then both (a) God has created rainbows and (b) rainbows happen due to the refraction of light. It is clear that citing both (a) and (b) as an explanation of rainbows is better than just citing (a). But it is far from clear that citing just (b) is better than just citing (a). On the contrary, it seems plausible that citing both (a) and (b) is better than just citing (b).
    Of course, if theism is true, then citing just (b) is better than citing both, because both aren’t true. But that begs the question against theism.

    September 14, 2012 — 8:26
  • “Of course, if theism is true, then citing just (b) is better than citing both, because both aren’t true. But that begs the question against theism.”
    Did you mean “Of course, if theism *isn’t* true…” or “Of course, if theism is *false*…”?

    September 14, 2012 — 14:49
  • DL

    Bjorn-Are: One issue I think deserve some comments is that part of his argument depends on “God of the Gap”-thinking being the norm or part of some extremely important arguments in Theistic Natural philosophy.

    I think this is an important point. You won’t find somebody like Aquinas making “God-of-gap” arguments, and in some ways it seems that that way of thinking really came into its own alongside the modern scientific mindset, with its non-traditional way of carving up reality into two separate sides. As Alex points out, you can give an answer that is both (a) and (b), and this seems to be much more how people actually thought back then (they were just a lot fuzzier on the (b) side).

    Kenny Pearce: the fine-tuning argument says ‘there are things that natural science tries to explain that it hasn’t been able to explain so far, so we should posit God as the explanation.’

    I agree that the argument is often portrayed that way by its opponents, and even sometimes by its (alleged) proponents, but that surely cannot be right, because in that form, no actual fine-tuning comes into it. The argument that “we can’t explain where these constants came from, therefore God” is faulty, but the point of bringing fine-tuning into it is that we need to explain something we do know rather than something we don’t. If we’re playing cards and you accuse me of cheating because in every hand I deal myself four aces, it won’t do me any good to retort, “You’re only saying that because you don’t know how the cards got that way.” You do know — either the cards got that way by random shuffling, or by my manipulating them, and you are arguing that the latter explanation is a far superior one to the former.

    September 16, 2012 — 14:56
  • Kenny Pearce

    DL: It is only sometimes part of the practice of physics to try to explain ‘where the constants come from:’ most physicists, I think, take seriously the idea that at least some constants might just be brute facts. What IS part of the practice of physics (pretty consistently) is to try to explain (away) instances of apparent fine-tuning.
    What I take to be one of the most objectionable features of ‘God-of-the-gaps’ arguments is that they are revisionary with respect to scientific practice: they tell scientists to stop looking for scientific explanations of certain phenomena and instead appeal to God. In the fine-tuning argument, the explanandum is not that there are constants of nature or that the constants of nature have these values, but that the constants of nature appear fine-tuned. This is something physicists seek to explain and are likely, one day, to succeed in explaining. (Furthermore, if they couldn’t explain it, that wouldn’t be evidence for the existence of a God of the western monotheistic sort, for the same reason that the occurrence of law-breaking miracles wouldn’t be; see here and here.)

    September 17, 2012 — 10:26
  • DL

    Kenny Pearce: In the fine-tuning argument, the explanandum is not that there are constants of nature or that the constants of nature have these values, but that the constants of nature appear fine-tuned. This is something physicists seek to explain and are likely, one day, to succeed in explaining.

    I don’t think we can assign any value to how likely science is to find that sort of solution, but I’m still not convinced that that captures what is peculiar to “fine tuning”. If the initial constants, say, have a 1/n possibility of being this way, and n is large, one could say, “We have no explanation for why that particular choice came up, therefore God must have done it” and that would be a “gap” argument. But to claim it’s fine-tuning is to claim that there is some specific pattern present, and that in no way suggests that science cannot continue to investigate how that pattern came about — any more than your accusing me of cheating in cards would suggest that science cannot investigate how I stacked the deck. In fact, there indeed will be a scientific explanation for how I managed to manipulate the cards without your noticing, but the point is that I manipulated them a certain way, not that nothing further can be said.

    (Furthermore, if they couldn’t explain it, that wouldn’t be evidence for the existence of a God of the western monotheistic sort, for the same reason that the occurrence of law-breaking miracles wouldn’t be; see here and here.)

    Thanks for the links. I agree that such an argument is for various reasons not a great way to reason to the existence of God (especially since there are better ways). But if you were actually in a position to show that the universal deck had been stacked, I think that legitimately points to “something” beyond physics.

    September 17, 2012 — 23:29
  • Kenny Pearce

    On your first point: if the claim is that the fact that the constants seem (close to) optimal for life is evidence for the existence of God irrespective of whether there is a physical explanation of those values, then I agree that there is a good argument for the existence of God in the neighborhood (something closer to what I take Leibniz to be up to in his discussion of teleological arguments). I do not, however, think this is what most fine-tuning proponents are doing. Typically, they are saying we should believe in God because God is a better explanation of the values of the constants than any currently existing physical theory.
    On your second point: if the ‘universal deck’ were stacked from the beginning to play out in a particular way that seemed to exhibit purposiveness, that would be good evidence for some kind of god, and maybe even a traditional monotheistic sort of God. If there were cards being dealt from the bottom, so to speak, (that is, if there were continual interventions) this would be evidence for some kind of supernaturalism, but not for traditional monotheism, since a traditional monotheistic sort of God wouldn’t need to fiddle with thing to get them just the way he wants them.

    September 17, 2012 — 23:42
  • Chad:
    Yup, that’s what I meant.
    Everybody:
    Suppose that I have no non-agential explanation of a particular complex of crop circles, and I offer an agential one that a person or persons unknown wanted to make us think there were aliens. It’s reasonable to infer that this explanation, or something like it, is true.
    Of course it is also obviously true that one day science might come up with a non-agential explanation. But this might-claim is no reason not to give the agential explanation. We would be hard pressed to explain much if we could only give explanations that could not ever possibly be undercut by future science. (Indeed, then we couldn’t give scientific explanations.)
    So if in fact right now science cannot explain something, but theism can offer a good supernaturalist agential explanation (the main ingredients being: plausible motives that a supernatural agent might have and giving a story about modus operandi), what’s wrong with giving that explanation? If it is in fact the best explanation, then that gives us reason to think it likely to be true. That science might one day weaken or undercut the argument only shows that the argument doesn’t yield apodeictic certainty. But what’s wrong with arguments like that?
    Now, granted, it would be a bad thing to then try to stop scientists from trying to find a scientific explanation. But a confident arguer from the gaps doesn’t do that. A confident arguer from the gaps says: “You might find a scientific explanation, but I bet you won’t. Try your best!”

    September 18, 2012 — 16:07
  • Dianelos Georgoudis

    I would like to suggest that what the physical sciences actually do is to *discover* mathematical patterns present in physical phenomena (which themselves constitute but a part of the total set of data at our disposal). Since such patterns allow us to predict future phenomena (or, less usefully, to retrodict past phenomena), it is proper to say that physical theories explain the respective physical phenomena. But physical theories need not describe the reality, physical or otherwise, which gives rise to the phenomena thus modeled. Now in classical physics it did happen to be the case that the mathematical model describes an actual physical model which gives rise to the respective phenomena, but in non-classical physics this is no longer the case. For the last 100 years or so scientific knowledge has grown by leaps and bounds *without* any description of the underlying physical reality. Not for lack of after the fact trying though, hence the so-called interpretations of quantum physics. Significantly the original and more “natural” Copenhagen interpretation did not fit with naturalism, because according to it consciousness is the fundamental reality. Later some naturalism-friendly interpretations were found (such as the many worlds interpretation) but they are exorbitantly implausible, indeed in my judgment more implausible than the most fantastic religious myths. In any case, as Nick Herbert writes in his excellent “Quantum Reality”: “One of the best-kept secrets of science is that physicists have lost their grip on reality“. Most people though, both naturalists and theists, appear to still believe that the physical sciences are in the business of describing reality and do so very successfully. (Philosophers know that it is the business of metaphysics to describe reality, but they let scientific realism – which is just one metaphysical theory – set the tone.)
    Thus the apparent fine-tuning of the values of the fundamental constants and initial conditions is *not* something that the physical sciences have to explain. Rather this is a rather unexpected property of the patterns that constitute the very powerful state of modern scientific knowledge. Since that property easily fits with theism but does not fit with naturalism, it is naturalism that has some explaining to do.
    Now many naturalists put their hope in future scientific developments. Indeed it may be the case that deeper patterns (i.e. more powerful theories) yet to be discovered will be such that they will account for these values, the way that a deeper pattern incorporates or integrates more superficial patterns. Nevertheless the history of science is such that the theist may suggest an inductive argument that such future theories will be even more fine-tuned. Perhaps even a logical argument can be crafted. Therefore, arguably, many a naturalist’s faith that future science will solve naturalism’s problem with the apparent fine-tuning is misplaced.
    The difficulty I see with naturalism is in conclusion this: Naturalism must explain the structure of reality without basing it on any purposeful action; no ultimate agential explanations are allowed. And, thanks to science, we now know that many naturalistic realities are possible in which intelligent life will evolve and which are not fine-tuned the way actual reality apparently is. Incidentally, what is even more difficult for naturalism to account for is the fact discovered by science that the actual reality is moreover of a deeply mathematical nature. Here, not even the multiverse hypothesis is of any help to naturalism. The fact then remains that for the past 100 years or so scientific discoveries have rendered naturalism less probably true, and that there is no reason to think that this trend will reverse itself in the future.
    As for the suggestion that the fine-tuning argument is a “God of the gaps” argument: I disagree that this is so for the same reasons others have pointed out above. But I would like to suggest that the atheologian’s argument from evil constitutes a “naturalism of the gaps” argument, since it is based on a lack of knowledge. To use Kenny Pearce’s wording, that argument says “there are evil things that theism tries to explain that it hasn’t been able to explain so far, so we should posit naturalism as the explanation”.

    September 20, 2012 — 2:48
  • Leave a Reply to Kenny Pearce Cancel reply

    Your email address will not be published. Required fields are marked *