Rich Lowry: Iran's terrible rationality

The chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey, thinks that Iran is a “rational actor.” He is indisputably correct.

Tehran couldn’t have made itself into the world’s foremost exporter of terror and extended its tentacles throughout the Middle East without resorting to rational calculation. That’s obvious. What Dempsey is implying, though, is that a regime capable of such calculation can necessarily be deterred if it gets a nuclear weapon. That’s an unsupportable leap.

If the Soviets, the famous “evil empire” bristling with thousands of nuclear weapons, could be deterred, why no...