Residual Categories Make for Tough Social Science

One of the basic realities in any effort to categorize things is that a bunch of stuff is left over.  They are put into a separate category of other stuff.  Any effort to give it a sense of unity is likely to stretch the concept so far that it bursts.  The exemplar would be Clash of Civilizations where "Sub-Sarahan Africa" does not fit into other categories and is thus considered being one civilization.  The problem is that it does not actually have any real unity is akin to the stuff that unites all Hindus, Westerners, Muslims (Clash is mostly about religion), and so forth, opening up the author (Sam Huntington) to charges that he is was racist.  That and Central and South America are seen as a civilization distinct from other Catholic countries (Italy, Portgual, Spain, etc) because the folks there are .... um, brown.

Anyhow, this clip illustrates the challenges of the residual category: