Twenty-two years ago, Nobel Prize-winning economist Paul Krugman wrote for The New York Times Magazine about the era in which he and I both grew up, when the top income tax rate on the morbidly rich ran between 74 and 90 percent. “[T]he America I grew up in — the America of the 1950’s and 1960’s — was a middle-class society, both in reality and in feel. The vast income and wealth inequalities of the Gilded Age had disappeared. Yes, of course, there was the poverty of the underclass — but the conventional wisdom of the time viewed that as a social rather than an economic problem. Yes, of course…