Monday, July 15, 2013

Philosophy of Religion, Part 4: The Fine-Tuning Argument, Part 1

I'm behind on these posts - but I intend to keep writing them. This one's huge, so I split it into two parts. I anticipate at least four more philosophy of religion posts after the fine-tuning sequence.
Swinburne, "The Argument to God from Fine-Tuning Reassessed"
Bostrom, "Anthropic Bias"
The teleological (or "design") argument for the existence of God, killed centuries ago by the theory of evolution, has been resurrected by modern physics, seemingly stronger than before. The fundamental parameters of the universe - the mass of the electron, the electric force constant, the initial rate of inflation, and many more - all fall within such a precise range that any slight initial difference in one of these parameters would have prevented the existence of an environment that could support life. This is so unlikely, the reasoning goes, that it seems the universe was "designed" precisely to support life. The problem with this way of stating the argument is that it leads the conversation towards the false dichotomy: either the universe has an intelligent designer, or it exists this way by brute chance. Brute chance is a silly hypothesis, so we are forced to accept the "design" conclusion, whatever that entails. Instead, a more honest way to state the argument is as follows:
Due to the a priori unlikelihood of fine-tuning in favor of life, we infer that there must be something about life which makes probable the existence of a universe containing it. But what sort of thing would make the existence of life probable? A personal designer who intends to create conscious beings seems like a reasonable hypothesis.
This is similar to how apologist Richard Swinburne states the argument. But notice that this second formulation is friendlier to other possibilities. The restatement of the argument reveals the assumptions on which it is based:
  1. The universe is in fact fine-tuned
  2. Fine-tuning is unlikely, a priori
  3. Life is the thing being tuned for, and is not just a byproduct of whatever is actually being tuned for
  4. Design is admissible as a hypothesis
  5. There are not other reasonable hypotheses that would make life probable

Let's address these one at a time. Number one: is the universe in fact fine-tuned? There are several approaches one can take in questioning this assumption.
  1. Dispute that our models of the universe suggest fine-tuning at all. True, if we vary one parameter independently of the others, the universe could be inhospitable to life. But maybe if we changed multiple parameters at once, different sorts of life could easily form. Maybe there are such a vast number of alternate combinations, each with its own version of life, that it was very likely for one such universe to exist. Then our version of life only seems special due to anthropic bias. This is an objection worth exploring, but on current models it is nevertheless the most dubious of the three approaches.
  2. Agree that the universe is fine-tuned for life, but argue that it is not fine-tuned enough to suggest a designer. This approach refers to the vast, inhospitable vistas of the cosmos, and how life is nothing but a thin film of scum on a pale blue dot, fragile and ever on the verge of annihilation. If the universe were designed specifically to harbor life, why is most of the universe uninhabitable? This approach has some merit, and seems to overlap with the argument from the problem of evil. It might be more strongly confirmed if we discovered sets of physical constants that would cause life to flourish even more than it does now.
  3. Criticize the fine-tuning argument for being too dependent on current models of the universe. Models and theories are subject to change. Although current models of physics strongly suggest that the universe is fine-tuned, we might eventually discover a better model of the universe in which the fundamental parameters all flow logically from a single law. Then there is no fine-tuning after all, because the parameters were never subject to change freely. So the fine-tuning argument becomes another God of the Gaps argument. I think that this is the most promising tack. In fact, I think it is reasonable to infer, on the basis of fine-tuning itself, that our current models are flawed in some way, even if we can never find out the nature of the "true" model. I attribute my favorite analogy to Stephen Hawking in his book The Grand Design. The analogy goes as follows: we are like fish living in a round fishbowl. We can look through the side of our fishbowl and see objects and movements, and devise laws to explain their interactions. But the laws that we devise, although they are able to make accurate predictions, will be rather complicated, due to the fact that everything we see is refracted and warped by the fishbowl. We have no way of leaving the fishbowl to see things as they really are - so we must stick with our overly complicated theories of motion as our best working model.
Two, is fine-tuning unlikely a priori? On the one hand, it is a necessary truth that observers must observe a universe hospitable to life. This is known as the anthropic principle. On the other hand, if the fundamental parameters of the universe just varied randomly, our very existence would be absurdly unlikely. But, as in the third approach above, we don't know whether or not the parameters vary freely. I don't see how we could possibly know, or even have an inkling, that the set of universal parameters that we see is unlikely to exist a priori. But I guess that this is the point of fine-tuning arguments in general - the randomly varying model is so absurd that we should infer that some alternative hypothesis to random variation must be true. So the second assumption is trivially true, I suppose, if random variation of parameters is our default position.
Three, is life actually what's being tuned for? Maybe some mechanism tunes the universe in favor of a very active chemistry, and life was only a byproduct of the active chemistry of the universe. Maybe the point of the universe is something like this. Because we are intelligent, we think that we have a special place in the universe. But maybe we don't have any special place - maybe the universe doesn't revolve around us. This is, of course, the Copernican principle: we are not the center of the universe.
Fourth, is design admissible as a hypothesis? The problem is that it is too vague - If God is the designer, which God is it? Christian, Islamic, Hindu, or some aloof watchmaker who set the universe ticking and no longer interferes? And as I argued in my second philosophy of religion post, the idea of "design" itself makes a category error. "Intentional causation" or "design" is, in our experience, inextricably linked with the evolved material brain. Therefore, design is not a fundamental mode of causation, but an emergent mode of causation, and one of the very things that we are trying to explain. To project human-like intent onto some abstract, necessary cause of the universe is extraordinarily presumptuous. In response to this, I have heard it argued that God does not have a human mode of intent, per se, but a mode of causation that's only analogous to intent. But this is fundamentally mysterious; if we can infer that God has such a mysterious means of causation, then we can also infer alternate hypotheses with equally mysterious modes of causation, all of which are "analogous to intent", but none of which require a personal God who is concerned about your daily life.
Fifth, are there alternate hypotheses that can explain fine-tuning equally well? (Assuming, for the moment, that design is a legitimate hypothesis). Yes, there are three (broadly speaking):
  1. The multiple universe hypothesis: many randomly-varying universes exist, most of which are inhospitable; but now and then, by sheer chance, one of them turns out to support life, and this is such a universe that we find ourselves in.
  2. There is a fundamental law that necessitates the physical constants we see (this was discussed above)
  3. The unknown other - some incomprehensible (but not Godlike) entity caused the universe to be the way it is.
We already discussed (b). (C) is essentially the position of "I don't know why the universe exists, and I'm not sure we can ever know, but I don't think that a God is responsible." I would say that this is a respectable position. The origin of fine-tuning is really a mystery, with no obvious explanation. But in light of the ambiguity, we can say that one hypothesis in particular, the God hypothesis, is probably not the case; that is, if the existence of God is disconfirmed by other evidence, such as the problem of evil or the material basis of consciousness, then we have every right to ignore it as a possibility and fall back onto "I don't know."
See the next post for a discussion of (a)...

No comments:

Post a Comment