Very true (and parent makes a really good point, also).

I do wonder: rather than a single axis, how many would be appropriate? If you did PCA on... well, some crazy mishmash of factors -- demographic, political, socioeconomic, geographic -- what would be the eigenvalues of today's US politics? (And what's the minimum sensible number of values to capture the range of experience?)

Man, I can just hear my cofounder exhaling in frustration, at such an ill-posed problem, and abuse of terminology... and no doubt there are real, quantitative answers to some of this (and PCA is probably naive compared to... latest whiz-bang etc)... But still.