I’m going to try to be as charitable as possible on this argument, but it this is how it seems to go:
- The universe is such that it allows for the gradual evolution of intelligent life under certain circumstances
- It could have turned out any number of other ways, almost all of which would not have allowed for such life
- The best explanation for this particular universe is that an intelligent transcendent creator finely-tuned it for life
- Therefore, an intelligent transcendent creator of the cosmos exists. QED.
I will admit that such an argument has a certain intuitive appeal, but only the first of its three premises are well-established. The second premise has been cast into serious doubt by professional cosmologists such as Victor Stenger, but it should not take a Ph.D. in physics to see that the third premise is quite problematic in and of itself. To illustrate why, consider an argument about the conditions that prevail on our own planet:
1. Earth is such that it allowed for the gradual evolution of intelligent life under certain circumstances
2. It could have turned out any number of other ways, almost all of which would not have allowed for such life
3. The best explanation for this particular planet is that an intelligent transcendent creator finely-tuned it for life
4. Therefore, an intelligent transcendent creator of the Earth exists. QED.
When you get to premise three, you should wonder whether other planets exist which might be similarly situated to our own. In the age of Sagan, Asimov and Rodenberry this is not a particularly great stretch of the imagination. Only a few hundred years ago, though, this second argument would have seemed perfectly plausible to W.L. Craig’s philosophical and theological forebears, who forbade the possibility of multiple worlds (sometimes on pain of death) and generally preferred the view that the Earth was uniquely created for humankind.
Suppose we consider only two rival hypotheses (a) metaphysical naturalism and (b) classical theism, excluding other possibilities for the sake of convenience. Given that living being exist (who are just intelligent enough to have thoughtful debates about metaphysics) the crucial question here is which of these hypotheses best explains the fact that the universe allows for the natural evolution and sustainment of intelligent life.
It should be clear that if intelligent minds exist and metaphysical naturalism is true, it is absolutely necessary that the laws of nature are such as to allow for the natural evolution and sustainment of intelligent life. By contrast, if classical theism is true, then minds can exist as souls apart from bodies, and there is therefore no need to posit a natural world which allows for life to emerge and flourish naturally over vast stretches of time and space. If God wants intelligent beings, He may readily create as many angels and demons as he pleases, endow them with free will. He need never give a thought to the idea of mucking about with matter, much less minds made of meat. There simply is no need for such onerous fine-tuning, if theism is assumed to be true.