On any given night cable TV news will tell us how polarized American politics is: Republicans are from Mars, Democrats are from Canada. But in fact, writes Peter Wenz in Beyond Red and Blue, Americans do not divide neatly into two ideological camps of red/blue, Republican/Democrat, right/left. In real life, as Wenz shows, different ideologies can converge on certain issues; people from the right and left can support the same policy for different reasons. Thus, for example, libertarian-leaning Republicans can oppose the Patriot Act's encroachment on personal freedom and social...