Del Ratzsch, a professor of philosophy at Calvin College, published a great foundational book on design arguments back in 2001, and I’m just now getting around to reading it cover-to-cover. The book is called Nature, Design, and Science, and I recommend anyone interested in intelligent design arguments to check it out. Ratzsch is one of those philosophers who really deserves to be more famous than he is; he does solid insightful work. (And he’s a nice guy — he once told me (not completely seriously) that if only I’d convert, they’d be happy to hire me at Calvin.)
Ratzsch gives good criteria outlining under what circumstances we would take some pattern or structure to be designed. I find his criteria plausible, but what’s interesting is that I find a couple of the particular examples that he mentions offhand of phenomena we’d take to be designed implausible. Here is one example:
if we discovered on Mars a perfect hundred-meter cube of isotopically uniform titanium, and knew that no human technology had that capability, identification of that cube as both artifact and alien would be relatively trivial. (p. 18)
In fact, this isn’t at all obvious to me. There are non-artifact cube-like objects that are found in nature (though, admittedly, they aren’t _perfectly_ cube-shaped). Consider, for example, pyrite:
One might initially think, if walking upon a heath and coming across a cube of pyrite, that that cube was an artifact produced by design. But in fact, that cube has the same status as any random rock one finds on the heath. Given the existence of pyrite cubes on Earth, I wouldn’t know what to think if I came across a titanium cube on Mars.
Here’s another case where I disagree with Ratzsch’s particular example of what would count as design. Ratzsch says:
If there were processes which were only activated by energy beyond what any finite agency could generate — for example, infinite energy — such processes would thus constitute evidence that supernatural agency was involved.
Granted, Ratzsch just says that the process would “constitute evidence”, not that that process would constitute certain evidence, so perhaps I would agree with him, in that perhaps I would take such a process to constitute a tiny bit of evidence for supernatural agency. But I’m not even sure that I would do that. There are some aspects of the universe that physicists talk about, such as spacetime singularities and black holes and supertasks, where there are ways of looking at these aspects such that they involve infinities. Perhaps there are parts of the universe where the amount of energy is infinite. If I had to guess, I’d guess that that wasn’t the case, but if the physicists told me that that was the case, I don’t think I would take that as evidence for the existence of God; I’d just say that that’s another interesting fact that we’ve learned from physics.
However, I agree with Ratzsch’s overall point, that one can in principle get evidence for the existence of God. I argue for that a bit in this paper.