How much of politics can be lined up along one dimension?

Jason Weeden and Robert Kurzban report:

Despite occasional statements to the contrary, most political scientists have long known — going back at least to Philip Converse’s work in the 1960s, and probably farther to Walter Lippmann’s in the 1910s/1920s — that many Americans do not in fact show substantial ideological consistency across policy views, except among limited groups…The 20% of the adult population who are white voters with bachelor’s degrees show some degree of coherence when it comes to views on same-sex marriage and income redistribution.  But, when it comes to the 40% of the adult public who have one or none of these characteristics — including, for example, African Americans and Latinos without bachelor’s degrees and nonvoting whites without bachelor’s degrees — there is no tendency whatsoever for people who lean in a given direction on one of these issues to lean in the same direction on the other.  For the remaining 40% of the adult public, who have two but not three of these features (e.g., white voters without bachelor’s degrees), ideological coherence is barely measurable.

That is from their new book The Hidden Agenda of the Political Mind: How Self-Interest Shapes Our Opinions and Why We Won’t Admit It, interesting throughout.