Saturday, February 28, 2015

The Fine Tuning Argument

The Fine Tuning Argument

The fine turning argument (FTA) comes in a variety of forms, but it first starts with the alleged scientific observation that the physical universe is such that, if any of various constants (found in the equations of laws of physics, such as the gravitational constant) and quantities (such as the distribution of mass and energy in the universe) were altered even slightly while keeping the same physical laws constants (that is, the equations are the same apart perhaps from the constants they contain) the universe would not possess intelligent, interactive life (not just our type of life, but any kind of intelligent, interactive physical life). The question: how to explain the fact that our universe has intelligent, interactive life as opposed to not having it? A deductive form popularized by Christian philosopher William Lane Craig:

  1. The fine tuning of the universe is due to either physical necessity, chance, or design.
  2. It is not due to necessity or chance.
  3. Therefore, it is due to design.

Alternatively, it could just be said that design is the best explanation for the alleged fine tuning among the three alternatives.

Is Fine Tuning Real?

While there are some physicists who believe fine tuning is real, there are also some physicists who believe it is not, such as Sean Carrol and the late Victor Stenger. Maybe life in our universe is like water in a puddle; the water in a puddle flows to fit in to the shape of the hole. Similarly, evolution evolves life to fit in the universe. It’s not that the universe was fine tuned for life, but life, through evolution, fine-tuned itself for the universe. Similarly (so the objection goes), if the universe had different constants/quantities, other types of life could have come about, and fine tuning isn’t actually real. So one approach to this argument is to deny fine tuning, or say that nobody really knows whether it’s real.

On the other hand, physicist Paul Davies said, “There is now broad agreement among physicists and cosmologists that the Universe is in several respects ‘fine-tuned' for life.”[1] Atheist physicist David Deutsch accepts fine tuning and has said that the puddle analogy doesn’t hold water.[2] The person who wrote the book Just Six Numbers in 1999 that helped bolster fine tuning awareness was written by Sir Martin Rees, an atheist physicist. Fourteen years later, atheist physicists Stephen Hawking and Leonard Mlodinow The Grand Design would likewise affirm the reality of fine tuning.[3] Maybe all these people are wrong, but I’d be awfully hesitant to accept that. Yes, we can find at least a few physicists who reject fine tuning, but the mere existence of dissenting scientists isn’t enough—after all, there also exist bona fide dissenting scientists who deny evolution (though this is a small minority among scientists) and there are even some climate scientists who think humans play little role in climate change (though again they are far from the majority).[4] What matters more is where the scientific consensus lies, and though I’m not certain, I think it is more likely than not that the consensus of physicists knowledgeable of the fine tuning controversy is that fine tuning is real, and that atheist physicists like Stephen Hawking are probably correct.

Attacking the Fine Tuning Argument: Physical Necessity

We don’t know of any physical necessity that forces the constants and quantities to be in the ranges that they are in. But does it follow that therefore there is no such physical necessity? I think not. William Lane Craig doesn’t give very good justification for discounting physical necessity as a viable explanation. So one possible explanation for fine tuning is some sort of unknown physical necessity. This is at least less extravagant than a hitherto unknown magical deity.

That said, one weakness of this view (whether it is a fatal weakness or not I’ll leave up to you) is that the argument could be modified to allow for metaphysical necessity and possibility. Suppose it is true that some physical necessity X forces e.g. the cosmological constant to be within a certain narrow life-permitting range; the theist could argue that this physical necessity X is itself fine-tuned so that it drives the universe into this narrow range. While X is physically necessary, it is (so one could argue) metaphysically possible for X to be slightly different so that it drives the universe into a life-prohibiting range (that is, the universe could have been different than what it is to have different physical necessities, including X). And so positing X merely pushes the fine tuning problem back a step, and we’re left with more or less the same argument that has yet to be refuted.

One could argue that maybe this unknown physical necessity X is also metaphysically necessary, but even if that’s possible (in the sense that we don’t know it’s false with absolute certainty) many people would find it unlikely and implausible. My own two cents: I’m hesitant to accept physical necessities as metaphysical necessities. It seems to me that one of the reasons we need science to discover physical necessities is that the physical world could have been different from what it is and thus we need empirical investigation to figure out what the physical world is really like. To say that all physical necessities are metaphysical necessities seems about as suspicious to me as saying it’s metaphysically necessary for a universe to eventually have a blog named Maverick Atheism. Still, I’ll understand if not everybody has the same modal intuitions (intuitions about what’s possible and necessary) as I do.

Attacking the Fine Tuning Argument: Chance

By far the biggest attack against the trichotomy of proposed possible explanation is the dismissal of the chance hypothesis via the multiverse. While there is not (as far as I know) any evidence that the multiverse actually exists, there have long been scientific hypothesis of a multiverse, some of them being predictions of certain scientific theories. So one viable explanation is that there are an infinite or nearly infinite number of these universes and among this universe ensemble the constants and quantities widely vary. And because the multiverse is so huge (infinite or nearly so) odds are at least one will be life permitting. This scientific hypothesis would explain why there is a universe that permits intelligent interactive life, and it has the benefit of being a scientific hypothesis as opposed to appealing to a magical deity. When I read about cosmic fine tuning, I’m given the impression that the multiverse explanation is the most popular way to avoid a designer among atheist physicists.

There is a bit of scientific pushback from theists on this having to due with the sci-fi sounding “Boltzmann brains.” First some background. The term “Boltzmann brain” is named after nineteenth century Austrian physicist Ludwig Boltzmann. Quoting from Sean Carrol:

Boltzmann invoked the anthropic principle (although he didn't call it that) to explain why we wouldn't find ourselves in one of the very common equilibrium phases: In equilibrium, life cannot exist. Clearly, what we want to do is find the most common conditions within such a universe that are hospitable to life. Or, if we want to be more careful, perhaps we should look for conditions that are not only hospitable to life, but hospitable to the particular kind of intelligent and self-aware life that we like to think we are....

We can take this logic to its ultimate conclusion. If what we want is a single planet, we certainly don't need a hundred billion galaxies with a hundred billion stars each. And if what we want is a single person, we certainly don't need an entire planet. But if in fact what we want is a single intelligence, able to think about the world, we don't even need an entire person--we just need his or her brain.

So the reductio ad absurdum of this scenario is that the overwhelming majority of intelligences in this multiverse will be lonely, disembodied brains, who fluctuate gradually out of the surrounding chaos and then gradually dissolve back into it. Such sad creatures have been dubbed "Boltzmann brains" by Andreas Albrecht and Lorenzo Sorbo....

So the Christian apologist can claim that the multiverse explanation suffers from the invasion of the Boltzmann brains. Quoting William Lane Craig himself:

…if we were just a random member of a World Ensemble, then we ought to be observing a very different universe. Roger Penrose has calculated that the odds of our solar system’s forming instantaneously through the random collision of particles is incomprehensibly more probable that the universe’s being fine-tuned, as it is. So if we were a random member of a World Ensemble, we should be observing a patch of order no larger than our solar system in a sea of chaos. Worlds like that are simply incomprehensibly more plentiful in the World Ensemble than worlds like ours and so ought to be observed by us if we were but a random member of such an ensemble.

Here’s where the Boltzmann Brains come into the picture. In order to be observable the patch of order needn’t be even as large as the solar system. The most probable observable world would be one in which a single brain fluctuates into existence out of the quantum vacuum and observes its otherwise empty world. The idea isn’t that the brain is the whole universe, but just a patch of order in the midst of disorder. Don’t worry that the brain couldn’t persist long: it just has to exist long enough to have an observation, and the improbability of the quantum fluctuations necessary for it to exist that long will be trivial in comparison to the improbability of fine tuning.

While the Boltzmann brain rests on a scientific claim the objection is largely philosophical. Suppose it is true that the majority of minds are Boltzmann brains. So what? It is also true that the majority of minds that have ever lived were present in the same American state that I am in this decade. Should I therefore conclude that “design” is the best explanation for why I have been present in the American state in this decade, rather than chance? It would appear not. Or suppose I win the lottery; the odds that I would have this particular winning ticket is very improbable, but should I conclude design over chance? Certainly not. So one point of contention here is whether this Boltzmann brain business provides a genuine reason to reject the chance hypothesis. Why should we accept design over the “we won the cosmic brain lottery” hypothesis”?

Still, one of the lessons of Bayesian mathematics is this: given some hypothesis H and evidence E, the lower that P(E|H) is (i.e. the lower likelihood we’d see evidence E given some hypothesis H), the more E provides evidence against H. If it is very unlikely that we’d see intelligent interactive life given the chance hypothesis, and we do see intelligent interactive life, doesn’t this provide at least some degree of evidence against the chance hypothesis? Maybe, but how much could be disputed. After all, it is also very unlikely that I’d see myself winning if it wasn’t rigged for me to win it (in the absence of it being rigged, the odds of my winning the lottery are heavily against me). Yet if I won the lottery, I still would not have sufficient grounds to conclude it has been rigged for me to win. I’d need something more to conclude design over chance here. The apologist, it could be argued, likewise needs something more to reject the cosmic brain lottery explanation.

  1. Int. J. of Astrobiology 2(2): 115, (2003).
  2. The Anthropic Universe” 2006-02-18. Retrieved 2015-02-28.
  3. Hawking, Stephen; Mlodinow, Loendard. The Grand Design (New York: Random House, Inc., 2010), pp. 143-144, 157-162.
  4. Evolution, Climate Change and Other Issues PewResearch. 2009-07-09. Retrieved 2015-02-28. Scientific and Public Perspectives on Climate Change, Yale University. 2013-06-03. Retrieved 2015-02-28.