Many atheist/skeptics base their disbelief on a lack of evidence for a deity. If God exists, there should be evidence in the world around us. A universe created by an omnipotent power should be different than one that was created by random processes. If you're being honest, you have to admit that the universe we live in seems pretty fine-tuned for life, isn't it? Scientists have identified dozens of fundamental numbers whose values are just right for the existence of matter, space, planets, stars, and life. If any of those numbers were any different, life couldn't exist. Doesn't it look very much like some intelligence set the values of the dials just right so as to produce a universe that we could live in?This argument has been widely trumpeted by Christians who are not biblical literalists -- who may, in fact, accept such empirically supported models as the Big Bang and organic evolution, and who buy that the Earth is not six thousand years old, as the biblical chronology would have you believe, but six-some-odd billion years old. But despite these non-fundamentalists' buying the whole scientific process (which is all to the good), they still can't quite let go of the idea that a higher power must be behind the whole thing. And the "fine-tuning of the universe" is one of their main arguments.
It's called the strong anthropic principle. The universe is such a hospitable place, they say, that god has to have set it up just for us. But there's just one flaw in the whole thing; the central contention, that the universe is hospitable... just isn't true.
I mean, it all sounds very nice, doesn't it? God created the universe with us in mind, and this produced awesome places like Maui and the Florida Keys. The problem is, even here on our home planet, things aren't all that... friendly. Much of the Earth's land surface has a climate or topography that makes it pretty unsuitable for human life. (Being that it's midwinter in upstate New York, I'd throw my own home town into that category.) Even some of the more congenial places, places that are warm enough and have enough water and fertile soil to keep us alive, are prone to natural disasters like hurricanes, tornadoes, earthquakes, volcanoes, and mudslides. And if you leave the Earth, things only get worse; most of the universe is damn near a vacuum, and what's not is filled with black holes, quasars, asteroid belts, supernovae, neutron stars, and Wolf-Rayet gamma ray bursters -- the last-mentioned being capable of emitting an outburst of radiation so powerful that it could blast an entire solar system into oblivion.
Yes, well, what about the fact that all of the fundamental constants are set just right to produce matter? This was the subject of Sir Martin Rees' book Just Six Numbers, in which he describes what the universe would be like if fundamental constants such as the curvature of space, the fine-structure constant, Planck's constant, the speed of light, and so on, were different -- and all of these alterations produce a universe that would be inhospitable to the formation of stars and planets, much less life. And because we can't at the moment see any other reason why the constants are what they are -- i.e., there is no fundamental principle from which they can be derived, they seem arbitrary -- Rees and others argue that this is evidence of fine tuning.
I see two problems with this. The first is that it is an argument from ignorance; because we have not yet come up with a unified theory that shows why the speed of light is three hundred million meters per second, and not (for example) 25 miles per hour, doesn't mean that we won't eventually do so. You can't prove anything from a lack of knowledge.
Second, it seems to me that the strong anthropic principle is a backwards argument; it's taking what did happen, and arguing that there's a reason that it must have happened that way, that if it weren't designed, it wouldn't have happened that way. It's as if I were dealt a straight flush in poker (an exceedingly unlikely occurrence) and I argued that because it's unlikely, someone must have rigged the deck.
All we know, honestly, is that it did happen, for the very good reason that if it hadn't happened that way, we wouldn't be here to talk about it. This is called the weak anthropic principle -- even if the fundamental physical constants are arbitrary, there's no design implied, because in a universe with different physical constants, we wouldn't exist to discuss the matter. The only place such arguments are possible are universes where life can occur. Physicist Bob Park summarizes this viewpoint with the Yogi Berra-like statement, "If things were different, then things would not be like things are." Put that way, it's hard to see how it's an argument for a deity, much less an omnipotent one with our best interests in mind.
Anyhow, that's my response to the Argument from Design. Like I said, the person who wrote to me was really quite friendly about the whole thing, which (although we disagree about some fundamental ideas) is certainly an improvement from the spittle-flecked responses I sometimes get that suggest Satan is, as we speak, sharpening up his torture equipment with me in mind. So, for that, I'll just say, "Thanks for writing." Civilized discussion is, as always, the goal around here.