So what's our bitter partisan divide really about? In two words: class warfare. That's the lesson of an important new book, ''Polarized America: The Dance of Ideology and Unequal Riches,'' by Nolan McCarty of Princeton University, Keith Poole of the University of California, San Diego, and Howard Rosenthal of New York University....Now, to turn it to energy: The 1970s collapse of the liberal consensus resulted from any number of factors in combination: Nixon's corruption, Vietnam, the sexual, racial, and political revolutions of the 1960s, whatever. But it would be foolish to ignore the profound impact of the oil shocks. Not just on prices or energy policy - the oil shocks fundamentally undermined the post-war liberal consensus. (Sadly for me, the unofficial end of the liberal consensus - Reagan's inauguration - was mere weeks before I was born.) With the end of economic security, western politics took a turn away from a more social bent (stronger unions, progressive taxes, stronger government) to a nastier, more brutish form of capitalism.
What the book shows, using a sophisticated analysis of Congressional votes and other data, is that for the past century, political polarization and economic inequality have moved hand in hand. Politics during the Gilded Age, an era of huge income gaps, was a nasty business -- as nasty as it is today. The era of bipartisanship, which lasted for roughly a generation after World War II, corresponded to the high tide of America's middle class. That high tide began receding in the late 1970's, as middle-class incomes grew slowly at best while incomes at the top soared; and as income gaps widened, a deep partisan divide re-emerged.
I'm no determinist, but it's tempting to view the 20th-century expansion of labour and political rights as something that could only be sustained with a large and growing economy, fed with a large and growing supply of cheap petroleum. Certainly, the expansion of oil production and the expansion of politics both correspond to the same period - roughly the late 19th century until the mid 1970s.
This points to the broader reason why environmentalism is predominantly a left-wing issue: creating a sustainable economy is part and parcel of building a more socially just world.