Ross Douthat is a columnist for the New York Times.

THE last time the United States held a presidential election amid the mass unemployment left in a financial crisis’s wake, the challenger offered only a partial glimpse of what he would actually do in office. Mostly, he played the opportunist, attacking the incumbent party for spending too much and helping too little, for being indifferent to human suffering and for failing to balance the budget, for overtaxing and undertaxing and everywhere in between. He claimed to be offering a bold contrast of visions, but mostly he just relied on the unemployment rate to do his work for him.

That challenger was Franklin Delano Roosevelt. His 1932 convention speech — the first ever delivered by a nominee in person — was more detailed than the parade of generalities Mitt Romney offered last Thursday. But mostly it was a sprawl of unpersuasive economic analysis and highly convenient criticisms of the hapless Herbert Hoover. Hearing it or reading it, you would have known that F.D.R. intended to govern as some sort of liberal, as you would know from Romney’s speech that he intends to govern as a conservative. But you would be able to anticipate only the broadest outlines of the policy experimentation that ultimately defined the New Deal....