What remains? A pronounced and, to my mind, healthy skepticism. Much was made early in Obama’s presidency about his putative affinity for Reinhold Niebuhr, the moral theologian and proponent of Christian realism. Goldberg’s account substantiates the president’s Niebuhrian inclinations, especially evident in his willingness to question the reigning shibboleths of U.S. policy.

By shibboleths, I mean those precepts, dating from World War II and the early Cold War, that still pervade the foreign-policy establishment, accepted as valid not because they are empirically correct but because they are comfortingly familiar. As such, they obviate any need to think. For the sake of convenience, we may sum up those shibboleths in a single sentence: America must lead. Implicit in this summons to “lead”—a euphemism for the threatened or actual use of armed force—is the vision of a world in which the forces of light vie against the forces of darkness, with America charged with ensuring the triumph of good over evil.

That isn’t Obama’s world. In that regard, he may be America’s first post-postwar president. He simply does not buy into the Manichaeanism that prevailed during World War II and through the Cold War, and that still persists today in American political discourse, especially but not exclusively on the right.

The contrast with Obama’s immediate predecessor is instructive. After 9/11, George W. Bush reflexively framed his Global War on Terrorism as an extension and de-facto renewal of World War II and the Cold War. Through victory, Bush asserted, the United States would once more ensure the triumph of freedom. Invading Iraq would enable Americans to liberate an enslaved people, much as they had liberated Western Europeans in 1945 and Eastern Europeans in 1989.

While Bush saw his actions as historically grounded, he was drawing on a past that never actually existed, except as a product of American imagination. Once expedient even if largely fictive, that past has long since forfeited whatever utility it may have once possessed. Whether through background, upbringing, or temperament, Obama’s own attitude toward that past is one of indifference. As a consequence, his world is devoid of the moral certainties that Bush believed self-evident.

In addition to making him an infinitely more interesting human being, Obama’s appreciation for moral complexity leads him to pose questions that for Bush (not to mention for many of Obama’s own aides) lay beyond the pale. Goldberg does an admirable job of ticking off the range of previously sacrosanct issues that Obama has at least obliquely brought into play. What exactly does Great Britain bring to the “special relationship” that should justify its continuation? Even if Berlin was worth fighting for a half-century ago, why does it follow that Kiev is worth fighting for today? Does “the West” actually exist? And even if it does, why should the racially and culturally diverse United States choose to affiliate with that one particular tribe? With the world’s economic center of gravity shifting to Asia, what is the residual significance of free-riding Europe? How should radical changes in the global energy environment affect the status of the Persian Gulf in the U.S. strategic hierarchy? Given the paltry results achieved through myriad recent U.S. armed interventions in the Islamic world, what exactly is the present-day utility of force? Under what definition of the term “ally” do countries such as Saudi Arabia, Israel, and Pakistan—each routinely behaving in ways contrary to U.S. interests—qualify for that designation?