Barack Obama's coming request for Congress to "right-size and update" the Authorization for Use of Military Force (AUMF) against terrorism will be constitutionally fastidious and will catalyze a debate that will illuminate Republican fissures. They, however, are signs of a healthy development — the reappearance of foreign policy heterodoxy in Republican ranks.

Many events (U.S. military misadventures since 2001, the Syrian civil war, the rise of the Islamic State, the spinning centrifuges of Iran's nuclear weapons program) and one senator (Rand Paul) have reopened a Republican debate that essentially closed when Dwight Eisenhower won the 1952 Republican presidential nomination. One reason he sought it was to block Ohio's Sen. Robert Taft.

Taft's skepticism about NATO and collective security was not quite isolationism — a label bandied carelessly today by promiscuous interventionists — but was discordant with the postwar internationalism of the Republican establishment and the nation. Eisenhower's victory (and Taft's death the next year) sealed the Republicans' near unanimity that had begun to form in January 1945 when another Midwestern Republican senator, Michigan's Arthur Vandenberg, changed his mind.