After seeing Paul Krugman's recent reference to the song "Blowin' In The Wind," it occurred to me that the song presages an under-appreciated triumph of the 1960's left. The song, of course, is symbolic of an idealism that is widely thought to have led to disappointment. The song, of course, largely consists of generalized yearning that is hard to measure. ("How many roads must a man walk down before you call him a man?" Um, 285?) It does, however, contain one specific call for action: "How many times must the cannonballs fly before they're forever banned?"

Cannonballs have not actually been banned. But when's the last time you heard of somebody being killed by one?