Monday, June 17, 2013

More Detuning

If my Fine Tuning Argument for Naturalism (FTAN) is going to work, it needs to be supported with examples. To recap: the FTAN notes that, because God is (by supposition) all-powerful, there are many ways he could have created the universe other than by naturalistic methods. If we assume that the probability of any of these methods is equal, then there is a very small probability that we will discover that God has chosen a naturalistic method. (The assumption that "probability is equally spread over the various possibilities" is analogous to the assumption made in the usual Fine Tuning Argument for God (FTA for short).) If we find that observations agree with naturalistic methods, then we have a strong presumption against theism.

I already admitted that the FTAN in its original form doesn't quite work, because many instances of God intervening in a naturalistic process would be indistinguishable from a (somewhat different) naturalistic process. So what I need is to show explicit examples where a miraculous intervention would be distinguishable from a naturalistic process, and where the evidence available points to the naturalistic process. I gave a few in the earlier post, here I want to add to the list. (I won't make any attempt to estimate the degree of detuning here.)

1.) Age of the universe - If life evolved through naturalistic processes, then the universe must be old enough for evolution to have happened. If God created the universe, this need not be the case: there is no reason the universe couldn't be, say, 6000 years old. God could have placed humans, animals, plants, etc., on a ready-made earth, and human history could have proceeded in just the way it has.

In fact, we know the universe has been around for about 14 billion years - plenty of time for evolution to have happened.

2.) Age of the earth - Even if the universe is old, there is no reason the earth itself needs to be more than 6000 years old. God could have inserted an earth into a pre-existing universe, complete with animals, humans, etc.

Naturalistically, of course, the earth must be old enough for evolution to have happened. In fact, we know the earth is about 4.6 billion years old - plenty of time for evolution to have happened.

3.) The earth is dateable - Actually, if the earth was created separately by God, there is no reason for it to be any age at all. What I mean is this: The age of the earth can be determined by comparing the ratios of different isotopes in radioactive decay cascades. If God created the earth out of whole cloth, as it were, then comparing these ratios for different cascades would not lead to a sensible determination of the earth's age. Those ratios could have had any values God chose. Unless God was trying to fool us by carefully adjusting the ratios to give a particular, consistent, age for the earth, those ratios need not point to a single particular age.

In fact, we find that the isotope ratios do point to a consistent value of about 4.6 billion years. Once again, naturalism wins.

4.) Age of life on earth - Even with an old universe and an old earth, God could have simply zapped life into existence. He could have done this at any point in the evolutionary history of life, and evolution could have proceeded from that point. Or, he could have simply created all species in their present forms.

The fossil record shows that life has been on earth at least a billion years, and likely as much as 3.6 billion years. Needless to say, this is consistent with the naturalistic evolution of all current life forms.

5.) Common descent - If God created life on earth, there is no particular reason all life forms would be related to each other. He could have created each species individually (as indeed Christians thought for centuries), in which case there wouldn't be any relationship-through-descent.

Naturalistically, it need not be the case that all life is descended from a single common ancestor, either. In principle, life could have arisen on earth more than once. (Here I need to assume that life can arise naturalistically, which we do not know for sure yet.) However, given what we know about evolution, we can be sure that, in time, many different but related species will arise. Think of Darwin's Galapagos finches - many different species but all descended from a single ancestral species that somehow found its way to the islands. So, under naturalism, we expect to find many different species that are related by common descent.

In fact, we have strong reasons to believe that all life on earth is related by common descent from some original self-replicating life form. The evidence comes through the study of the anatomy of living organisms, through the fossil record that reveals the slow modification of life forms over vast periods of time, and through genetics that confirms the relationships deduced from anatomy and the fossil record. This is of course consistent with naturalism, but highly unlikely under theistic assumptions.

I should say again that I don't think this is a very good argument for naturalism. What I hope is that, by turning the fine tuning argument around, I can get you to see the problems with it. In my view the main problem is the assumption that probability is equally spread over the conceivable options. In the FTA, these options are the various conceivable values of the fundamental constants of nature. In the FTAN, the options are the various conceivable ways God could have created life on earth. In neither case do we have any good reason to think the probability is equally spread among  the conceivable options.

Can you think of other examples of ways God could have chosen to create life, but didn't?

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