Book excerpt: "Who are we?" is the question at the core of these fascinating essays from one of the nation's leading intellectual historians. With old identities increasingly destabilized throughout the world—the result of demographic migration, declining empires, and the quickening integration of the global capitalist economy and its attendant communications systems—David A. Hollinger argues that the problem of group solidarity is emerging as one of the central challenges of the twenty-first century. Building on many of the topics in his highly acclaimed earlier work, these essays treat a number of contentious issues, many of them deeply embedded in America's past and present political polarization. Essays include "Amalgamation and Hypodescent," "Enough Already: Universities Do Not Need More Christianity," "Cultural Relativism," "Why Are Jews Preeminent in Science and Scholarship: The Veblen Thesis Reconsidered," and "The One Drop Rule and the One Hate Rule." Hollinger is at his best in his judicious approach to America's controversial history of race, ethnicity, and religion, and he offers his own thoughtful prescriptions as Americans and others throughout the world struggle with the pressing questions of identity and solidarity.