This is the the twenty-first post in my Theories of Knowledge and Reality series. Follow the link for more on the series and for links to other entries as they appear. In the last post, I presented two versions of the design argument for the existence of God, along with some standard responses. This post focuses in on a third version, the fine-tuning design argument.
The laws of physics contain some constants that govern how things in the universe behave. Physicists have no idea why these constants have the values they do, but they know that if they had been just slightly different then we couldn't exist. Stars couldn't form, never mind rational life. (Some might argue that rational life vastly different from anything we've seen might still be possible. That is hard to speculate about, but perhaps it's worth considering.)
Physicists all accept this fact about the laws, which leaves philosophers to figure out what to say. Some argue that, since the chances are so low of getting these exact constants, it's too much of a coincidence that the constants we happen to have are the ones that allow the possibility of rational life. This leads some to conclude that the universe must have been designed with the purpose of leading to at least the possibility of rational life.
If I draw a straw out of a hundred straws to see if I survive or die, and I get the lucky straw, is it reasonable to conclude it was a setup? I can provide an explanation by suggesting that it was a setup. If I was the only one drawing, this is most likely. If there were enough other people drawing, I could provide another explanation that may be better in that case. If I knew that there were enough people that someone has to win, then maybe I'm just the lucky one. Someone had to be. I wouldn't be around to think about it if I hadn't been lucky, so it's no surprise that the person thinking about it survived.
However, in the case of the universe, we generally don't believe there are lots of universes and that this one is just the lucky one with life. If there's only the one universe, we can't say, "someone had to get it". There's only one universe drawing the straw, and it got the lucky one. That needs explaining.
Or is there just one universe? Lots of universes, each cosmos with different constants, would explain the surprising fact about the cosmological constants. It looks as if it's fine-tuned, but we happen to be in one of the universes with constants permitting rational beings. With so many possibilities actually occurring, one is bound to allow rational life. So this is parallel to the standard objections against earlier versions of the argument. With the complexity of life, the response is that given enough time it's not so surprising. With the origin of life it's that, given enough opportunities on enough planets over enough time, it's not so surprising. Here it's that given enough universes with different constants, one of them is bound to allow rational beings. We're just in one that does allow them. We couldn't be in one without the right constants, so there wouldn't be anyone there to wonder about it.
Many philosophers are happy to leave the argument there. Since there's an alternative explanation, we need not appeal to a designer. Things aren't so clear, however. In the next post, I'll look at the complexities involved with comparing these two explanations.