Causal density

From Controlling the Uncontrollable by Kevin Drum, a review of Jim Manzi's Uncontrolled and the concept of causal density.

The problem is what Manzi calls "causal density." If you're studying the orbit of a planet, you can pretty much assume there's only one important cause of the planet's movement: gravity. Causal density is low. In medicine, there are more things to worry about, but a lot of problems are still tractable. Causal density is moderate. But in human affairs, there are lots of causes of everything, there are causes of the causes, and the causes often interact in complex ways. Causal density is very high, which means it's very hard to make sure you've accounted for everything. No matter how sophisticated your statistical tools are, it's always possible that something you haven't thought of is lurking in the background and throwing off your results.

Love the concept. In discussing economic development as well the process of enthusiastic reading, I have cumbrously been referring in variant forms to complex, chaotic, self-regulating, non-linear processes. Causal density will do quite nicely instead.