So far, the 21st century is vexed by nothing so much as those supposed residues of humanity's infancy. Nevertheless, Marx's anticipation morphed into what Moynihan called "the liberal expectancy." It is the hope -- liberals tend to treat hopes as probabilities -- that the fading of those atavisms and superstitions has put the world on a path to perpetual tranquility.

The world McNamara has departed could soon be convulsed by attempts to modify Iran's behavior. Since a variety of incentives have been unavailing, more muscular measures -- perhaps "surgical strikes," a phrase redolent of the McNamara mentality -- are contemplated.

Some persons fault the president for not having more ambitious plans to somehow prompt and guide Iranians toward regime change. That outcome is sometimes advocated, and its consequences confidently anticipated, by neoconservatives whose certitude about feasibility resembles that which, decades ago, neoconservatism was born to counter.

Well. Every four years we saturate New Hampshire -- that small, English-speaking, culturally homogenous, ethnically temperate sliver of tranquil New England -- with politicians, consultants, journalists and political scientists. And often we are surprised -- even dumbfounded -- by how unpredictably that state's people, with their native perversity, choose to behave in their presidential primary.

McNamara, like many who leave high office, never left the capital of this nation that believes people learn from history, and that therefore history is linear and progressive. But the capital, gripped once again by the audacious hope of mastering everything, would be wise to entertain a shadow of a doubt about that.