To understand why Democrats ever picked Mondale, you have to understand where the party — and where the country — was in 1982 and 1983, when the nation’s verdict on Reagan and his policies was far less positive. In those days, with unemployment surging over 10 percent and the president’s popularity slipping to sub-Carter levels, Democrats mistakenly assumed that the ‘80 election had been a mirage. The electorate, they figured, had acted in haste and was rapidly returning to its senses. The results of the 1982 midterms, when Republicans (who had begun the cycle with claims that they’d win...