Conventional wisdom holds that elections are about the future. Or about the personalities of the candidates. Or at least about voters’ perceptions of the last four years. But a quick glance at history shows that’s not always so. Republicans won every election between 1868 and 1880—not because Ulysses S. Grant, Rutherford B. Hayes, and James Garfield were such fabulous candidates, and not because their Democratic opponents were so awful. Nor did they win because of the conditions in the country at the time. They won because when Americans thought about the Republican Party, they thought about Abraham Lincoln. And when they thought about the Democrats, they thought about Jefferson Davis.

The same thing happened after the New Deal. In 1948, Harry Truman was personally unpopular and Americans were in a foul mood. But Truman won in large measure because of the way Americans felt about the Democratic and Republican parties, impressions created less by him or his GOP opponent, Thomas Dewey, than by two guys named Roosevelt and Hoover, who had faced off in 1932. The same was true in 1988, when George H.W. Bush, a weak candidate in his own right, made his race versus Michael Dukakis another referendum on Ronald Reagan versus Jimmy Carter.