[ Author Bio ]
The key premise of the fine-tuning argument for the existence of God is the alleged improbability of the physical constants taking on values that fall within the narrow life-friendly range. In this paper Aron Lucas examines whether this improbability alone is enough to ground a successful theistic argument from design. He concludes that the fine-tuning proponent is impaled on the horns of a trilemma: he can either reject the argument for having a false premise, reject it for being circular, or accept it at the cost of rejecting the moral argument for the existence of God.
In Hume's Abject Failure, philosopher John Earman argues that David Hume's famous maxim that no testimony is sufficient to establish that a miracle has occurred unless its falsehood would be more miraculous than the miracle itself is just a trivial tautology, namely that we should not believe a miracle claim unless the evidence makes it more probable than not. But even if this interpretation is correct, contemporary Christian apologists fail to satisfy Hume's purportedly obvious condition that it must be more probable that a miracle occurred than that it did not occur when they argue that the miraculous resurrection of Jesus probably occurred.
If the values of the physical constants of our universe were even slightly different, life could not exist. Some have argued that the fact that life does exist thus provides strong evidence that God fine-tuned these values to allow life to emerge. According to the fine-tuning argument, the existence of a life-permitting universe is very improbable on naturalism, but not so on theism. However, we have no way of determining the probability or improbability of actualizing a life-permitting universe on naturalism, for we can only compare our universe against the infinitesimally small subset of other possible universes that have the same physical laws—not the infinite set of all other possible universes.