Reading "Our Divided Political Heart," the new book by Washington Post columnist E.J. Dionne, is a bit like examining a high-resolution MRI of the body politic at a time when hyper-partisanship, feverish rhetoric and perpetual gridlock seem like the symptoms of a terminal political illness.

Yet in a nuanced book bolstered by history, Dionne argues that the underlying disease -- chronic friction between twin impulses of individual freedom and the need for a self-governing community -- is in our political DNA. Rather, it's the modern, overheated expression of those impulses that has created the sense that our political system is irreparably broken.

To observers, the apparent breakdown of democracy stems from a calcified red-state/blue-state divide, coupled with tit-for-tat political warfare and the arms race of special-interest money. Taking the long view, Dionne identifies an aggravating imbalance between those who want less government and more freedom (think Tea Party) and those who want government to protect the greater community -- key to the Occupy Wall Street movement.

In modern times, Dionne writes, the ever-present divide between progressive "communitarians" and conservative "individualists" has split into a chasm, unbridgeable because history itself has been politicized; we can't agree on the facts.

Post-Reagan conservatives have shifted so far to the right they won't admit the Constitution creates government and doesn't abolish it, Dionne argues. The Founding Fathers -- a brilliant but imperfect group of men, he notes -- wrote an elastic, occasionally vague document that was designed to grow.

The Constitution was "conceived in argument," Dionne writes, because its authors "understood that preserving the liberty they so prized depended upon virtues and forms of solidarity that an individualistic conception of freedom could not sustain on its own."

Dionne, an unabashed liberal, contends that his side has abandoned that argument over the years; few blue-staters rally around the sophisticated notion that liberty and government go hand-in-hand. Meanwhile, he writes, progressives and the white working classes that should be their base have irrevocably split.

Dionne presents a mash-up course in philosophy and graduate-level American history, written in an avuncular style with choice nuggets of deadpan wit. Citing a range of scholars and historians ranging from Alexander Hamilton to New Yorker blogger Hendrik Hertzberg, he reveals, among other things, that taxes and commerce are interdependent; that the Tea Party's view of the Constitution and of itself are erroneous; that progressive and conservative thought have evolved so much they've almost traded places.

Most striking, however, is the fact that the nation's checkered racial history -- slavery, the Civil War, Reconstruction, the civil rights movement -- has been a consistent fault line in the political divide between individual and community. African-Americans' uneasy place in an ambivalent, sometimes hostile society has influenced or lingered over civic turning points, including reactionary opposition to the nation's first black president.

"We Americans are a confusing people," Dionne writes, "perhaps especially to ourselves."

Joseph Williams, a former assistant managing editor at the Star Tribune, is a writer and editor for Politico.