American exceptionalism is the oldest and most contentious of the alleged national exceptionalisms: arguments that a given nation must be understood in essentially idiosyncratic fashion. John Winthrop, Alexis de Tocqueville, and Karl Marx helped develop and sustain an American variant for the first 350 years of a separate American political life. Modern political scientists have addressed the notion in a more systematic and methodologically self-conscious manner during the past half century. Nevertheless, much of the argument revolves around conceptual issues, operational difficulties, and empirical traps, so that these must provide the contours of the subject here. Two major recent books with sharply divergent conclusions, both marshaling extensive empirical evidence, serve not only as a means of updating the classical argument and of presenting its modern opposition. Both also suggest, indeed contribute, further reasons for the continuing lure of a difficult and divisive notion.
