Regarding my response to Stephen Meredith’s targeting of intelligent design in First Things, a reader asks:

I keep coming across the phrase "rarefied design" in Michael’s essay, such as in "Nature manifests evidence in some ways for rarefied design." I misread this as "reified design" (which makes more sense in context), but then noticed it was actually "rarefied" when he kept repeating it. 

Thinking of rarefied pertaining only to thin air, I looked it up and learned it can also mean noble or of a high nature. This might make sense, but I still am unsure whether he actually meant to say reified (making something abstract concrete, as when the effects of abstract intelligence are embodied in physical objects, allowing us to infer design).

Anyway, if it is a typo, it is worth fixing. And if it is not a typo, pardon my ignorance.

It’s a good question. I thought "rarefied design" was in common parlance, but I guess not.

The first place I came across it was a post by Jeff Shallit a few years ago. Rarefied design is design for which there is no detailed causal story. "Rarefied" implies "exclusive" of such a story. 

It differs from ordinary design in that most of the time we encounter design (ordinary design), we have a straightforward explanation as to how it got here. My car, my computer, my watch were manufactured by agents I know (people) in ways that I know (factories).

Rarefied design is design where I know nothing about the agent or the manner in which the design was performed. SETI and ID are scientific efforts to find rarefied design. We don’t know (in any scientific way) who made the genetic code or how he (or they or it) did it. But we know it’s design.

The concept of rarefied design is useful shorthand for the kind of design in nature that David Hume ostensibly discredited in his Enquiry Concerning Human Understanding. Hume insisted that you can’t infer design (in nature) because you have no knowledge of the designer and the analogy between mundane human design and natural or divine design is too great an inferential leap. Basically, Hume argued that inference to design with a plausible empirical causal history is justified, but inference to design without a detailed causal history is unjustified.

ID, in my view, invokes rarefied design, in that it argues that design has hallmarks independent of causal stories. I think Hume was wrong in denying the inference to that kind of design. Hume was wrong about a lot of things. 

The discovery of a designed non-human artifact in outer space (a spacecraft, a computer, etc.) would be a clear example of the rational inference to rarefied design. We would have no knowledge whatsoever of the designer(s), having no experience with extraterrestrial designers. The artifact could be designed supernaturally, for all we know. But we know design when we see it. That stripped-down design is rarefied design.

Image: Portrait of David Hume, Scottish National Gallery/Wikipedia.