It’s not often — but not unpredecented — for Federal Reserve officials to make joint appearances. But Tuesday night’s gathering when Richmond Fed President Jeffrey Lacker hosted Chicago Fed President Charles Evans was notable for the debate format that ensued from the opposite ends of the monetary policy spectrum.Lacker is a reliable hawk, who wants the central bank’s bond buying efforts to stop, and dissented on every policy decision last year (he doesn’t have a vote this year). Evans by contrast is a dove among doves, and an influential member who came up with the idea — now adopted by...