The introduction to James Campbell's new book over at Princeton University Press:
Voters are not fools.
—V. O. Key, Jr. The Responsible Electorate
America is polarized. Our political parties are highly polarized and the American electorate is highly polarized. By highly polarized, I mean there are substantial differences in political perspectives across a single ideological dimension. Liberals versus conservatives. Fundamental political differences slice through broad segments of the American electorate and separate the political parties on a wide range of important issues. The polarization of the American electorate is real and widespread. It is not an artifact manufactured by polarized political parties, manipulative politicians, rabble-rousing talking heads, myopic interest groups, or mischievous gerrymanders. It is not limited to rarified groups of political leaders or zealous activists, or even the politically engaged. Nor is it constrained to only a few contentious, hot-button issues. It is not an illusion formed by forced choices in elections or geographic clusterings of the like-minded. Political divisions in American politics are now deep and real.
Despite this reality, the idea persists that America is a moderate nation and that most Americans are moderates. That is a myth. Most Americans are not moderates. Not even a slim majority of Americans voting in recent elections are moderates. Some are to the left, some to the right, and together they outnumber those in the middle. America is a politically divided nation, it has been so for some time, and has become more so in recent decades.
While the American electorate and its political parties are quite polarized, the extent of polarization should not be exaggerated. Though a majority of voters are not moderates, moderates are still a large and important minority. And even among the majority of the electorate who are not moderates, few could properly be called extremists. We are substantially polarized, but we are not a bimodal nation with half of the electorate at the leftist outer edge of the political universe and the other half on the extreme right wing. We are highly polarized between liberals and conservatives, not between totalitarians and anarchists.