The Schlesingers’ methodology was, to put it mildly, problematic. First, because no objective criteria were established, the conclusions are impressionistic, almost by definition. Second, under their system, there’s no way to assign a president credit for a success and give him demerits for a failure. For that reason, their ratings are incomplete and misleading. Lyndon Johnson, for instance, is lauded for his civil rights record and faulted for his disastrous Vietnam policies, but the only way to reconcile the two areas is to give him an “average” grade. This is particularly discordant for LBJ, who didn’t strike anybody who knew him as average on any day of his life.

The third weakness in the Schlesingers’ ratings racket is their obvious ideological bias. They basically polled their pals, which is to say, fellow liberals—and political activists at that. How liberal? How activist? Schlesinger Jr. co-founded the left-wing Americans for Democratic Action. He also worked in the Kennedy and Johnson administrations, and was such a Democratic Party partisan that he wrote an acclaimed biography of Andrew Jackson without mentioning the Seminole Indians or Cherokees or the Trail of Tears.

The younger Schlesinger’s jury of experts in the 1990s included several historians who were signatories to a partisan and inflammatory newspaper ad attacking Republicans for daring to impeach Bill Clinton. Also among his panelists were two Democratic politicians, Illinois Sen. Paul Simon and former New York Gov. Mario Cuomo.