Hold on to your hats and prepare to be amazed: Milton Friedman has changed his mind. "The use of quantity of money as a target has not been a success," concedes the grand old man of conservative economics. "I'm not sure I would as of today push it as hard as I once did." Granted, this is hardly a conversion of Damascene significance. But, heck, it's a start. It also shows that, at the age of 91, Friedman still has his critical faculties intact. The man once described as "the most consequential public intellectual of the post-war era" is still...