I've kind of wanted to write about the concept-as-regularity thing for a while, but it seems akrasia is getting the best of me. Here's a compressed block of my thoughts on the issue.

Concept-as-regularity ought to be formalized. It is possible to conclude that a concept makes sense under certain circumstances involving other existing concepts that are correlated with no apparent determining factor. Since a Y-delta transformation on a Bayesian network looks like CAR, I'm guessing that the required number of mutually correlated concepts is three. Formalizing CAR would allow us to "formally" define lots of concepts, hopefully all of them. Bleggs and rubes are a perfect example of what CAR is useful for.