There’s an uncomplicated tale many Americans like to tell themselves about recent U.S. foreign policy. As the story has it, the nation was led astray by a powerful clique of political appointees and their fellow travelers in Washington think tanks, who were determined even before the 9/11 attacks to effect a radical shift in America’s role in the world. The members of this cabal were known as neoconservatives. They believed the world was a dangerous place, that American power should be applied firmly to protect American interests, and that, for too long, U.S. policy had consisted of diplomatic excess and mincing half measures. After 9/11, this group gave us the ill-conceived Global War on Terror and its bloody centerpiece, the war in Iraq.

This narrative is disturbing. It implies that a small cadre of officials, holding allegiance to ideas alien to mainstream political life, succeeded in hijacking the foreign-policy apparatus of the entire U.S. government and managed to skirt the checks and balances of the U.S. Constitution. Perversely, though, this interpretation of events is also comforting. It offers the possibility of correcting course. If the fault simply lies in the predispositions of a few key players in the policy game, then those players can eventually be replaced, and policies repaired.

Unfortunately, though, this convenient story is fiction, and it’s peddling a dangerously misguided view of history. The American public at large is more deeply implicated in the design and execution of the war on terror than it is comfortable to admit. In the six years of the war, through an invasion of Afghanistan, a wave of anthrax attacks, and an occupation of Iraq, Americans have remained largely unshaken in their commitment to a political philosophy that demands much from its government but asks little of...