Richard Swinburne adopted the Fine Tuning Argument as the heart of his ‘Teleological Argument from Spatial Order’ (The Existence of God, 2nd ed., p.167-190). The key premise of this argument mentions tuning:
“…the universe…[is] tuned–that is, such as to allow and indeed make significantly probable the existence of human bodies.” (EOG, p.188)
Here is another statement of the key claim:
“…the laws and boundary conditions of the universe…[are] such as to make probable the evolution of human bodies.” (EOG, p.189)
Various objections have been raised to the Fine Tuning Argument, but one potential problem strikes me as particularly interesting: Swinburne’s attempt to have his cake and eat it too.
As Swinburne wraps up this argument for God, he hedges his bet with the following footnote:
If however the evolution of human bodies was very improbable given the actual laws and initial conditions, but nevertheless occurred, then there would be an argument of a different kind to the existence of God. This would…be an argument from the fact that the laws and initial conditions [of the universe] are one of a small range of such that do not rule out the evolution of human bodies, and from the fact that nevertheless that evolution occurred even though it was very improbable. The conjunction of these two phenomena would be much more to be expected if there is a God than if there is no God.
(EOG, footnote #32 on page 189).
So, if the laws and initial conditions of the universe were such that they made the evolution of human bodies probable, that is evidence for the existence of God, but if the laws and initial conditions of the universe were such that they made the evolution of human bodies very improbable, then that too would be evidence for the existence of God. Heads, he wins; tails, we loose. It looks like the evolution of human bodies is evidence for God whether the laws and initial conditions of the universe made this event probable or very improbable.
Does this make sense? Can Swinburne have his cake and eat it too?
What if the laws and initial conditions of the universe made it only somewhat improbable that human bodies would evolve? Would this count as evidence against God?
Perhaps not, because Swinburne could claim that God, in order to give humans the freedom to reject belief in God, did not want to make the evidence for his existence too clear and obvious, so God designed a universe such that the evolution of human bodies was only somewhat improbable, and then God intervened to guide evolution in the right direction, leaving only modest and somewhat ambiguous evidence of his fingerprints on the world.
It looks to me like no matter what the situation turns out to be in terms of the probability of the evolution of human bodies, one can use that “fact” to support the existence of God. But if no possible cofiguration of the evidence counts against God, and all possible configurations of evidence count for God, then it would seem that the evidence is not really functioning to distinguish between different possibilities (i.e the possibility that there is no God, and the possibility that God exists).