Douglas E. Schoen is a political strategist and coauthor of the book Mad as Hell: How the Tea Party Movement is Fundamentally Remaking Our Two-Party System. Schoen has worked on numerous campaigns, including those of Bill Clinton, Hillary Clinton, Michael Bloomberg, Evan Bayh, Tony Blair, and Ed Koch.

Who was or is the best president of the United States since 1900? Newsweek recently polled 10 eminent historians and 600 randomly selected Americans about our country’s presidents. And the differences in their responses were striking.

The top two finishers among the public were Ronald Reagan and Bill Clinton, while the top two finishers among the historians were Franklin Roosevelt and Theodore Roosevelt. Jimmy Carter and George H.W. Bush both made the top 10—9th and 10th, respectively—in the public’s list, but not the historians’ rankings. And Lyndon Johnson and Woodrow Wilson—3rd and 5th, respectively, in the historians’ poll—didn’t make the public’s top 10.

How to account for these divergences? The most obvious explanation is that historians, true to their profession, seemed to place a greater emphasis on the distant past, while the public’s selections skewed toward recent decades...