Donald Trump is just one symptom of today’s cultural pathology of self-validating vehemence with blustery certitudes substituting for evidence. Another is the fact that the book atop the New York Times nonfiction best-seller list is a tissue of unsubstantiated assertions. Because of its vast readership, “Killing Reagan: The Violent Assault That Changed a Presidency” by Fox News’ Bill O'Reilly and his collaborator Martin Dugard will distort public understanding of Ronald Reagan’s presidency more than hostile but conscientious scholars could.

Styling himself an “investigative historian,” O'Reilly purports to have discovered amazing facts that have escaped the notice of real historians. The book’s intimated hypothesis is that the trauma of the March 1981 assassination attempt somehow triggered in Reagan a mental decline, perhaps accelerating the Alzheimer’s disease that would not be diagnosed until 13 years later. The book says Reagan was often addled to the point of incompetence, causing senior advisers to contemplate using the Constitution’s 25th Amendment to remove him from office. Well.

Reagan was shot on the 70th day of his presidency. In the next 2,853 days he produced an economic boom and the Cold War’s endgame. Among O'Reilly’s “explanations” for Reagan’s supposed combination of creativity and befuddlement are: He was brave; “on his bad days, he couldn’t work” but on good days “he was brilliant”; Nancy Reagan was in charge; it was “almost miraculous.”

When Reagan’s unsatisfactory Chief of Staff Don Regan was replaced by Howard Baker, a Baker aide wrote a memo that included slanderous assessments of the president from some disgruntled Regan staffers. This memo, later regretted by its author, became, O'Reilly says, the “centerpiece” of his book. On this flimsy reed he leans the fiction (refuted by minute-by-minutes records in the Reagan Library) that, in O'Reilly’s words, “a lot of days” Reagan never left the White House’s second floor where he watched “soap operas all day long.”

The book’s pretense of scholarship involves 151 footnotes, only one of which is even remotely pertinent to the book’s lurid assertions. Almost all contain irrelevant tidbits (“Reagan’s hair was actually brown”). At the Reagan Library, where researchers must register, records show that neither O'Reilly nor Dugard, who churn out a book a year, used its resources. The book’s two and a half pages of “sources” unspecifically and implausibly refer to “FBI and CIA files,” “presidential libraries” and travel “around the world.” They also cite Kitty Kelley’s scabrous 1991 Nancy Reagan “biography,” a sewer of rumors and innuendos that probably is the source of the sexual factoids O'Reilly and Dugard recycle.

Ed Meese was, from Sacramento to Washington, Reagan’s longest-serving adviser. George Shultz was Reagan’s confidant and secretary of state. James Baker served Reagan as chief of staff and treasury secretary. None was contacted in connection with the book. Scores of Reagan’s White House aides would have shredded the book’s preposterous premise, which might be why they were not interviewed.

For example, Mari Maseng, now Mari Will, worked with Reagan at the beginning and the end of his presidency. She worked with him as a speechwriter from 1981-1983. (As author of the speech he delivered at the Washington Hilton, she was walking ahead of him when the would-be assassin fired.) She returned to the White House in 1986 as director of public liaison. In 1988, as communications director, she worked down the hall from the Oval Office, having constant interactions with him. She saw no diminution of his physical energy or mental acuity.

Dugard sought research advice from former Rep. Christopher Cox, who served in Reagan’s White House counsel’s office. Cox put Dugard in touch with former California Gov. Pete Wilson and several Reagan historians. Wilson and Cox warned that historians’ criticisms could hurt the book’s reception. Then O'Reilly charged on Fox that Wilson and Cox somehow threatened him, adding gratuitously and falsely that Cox, as chairman of the Securities and Exchange Commission, “presided over the mortgage debacle that collapsed the economy in 2007,” an explanation of the autumn 2008 collapse that is simply weird.

Cox put the book’s publisher in touch with Annelise Anderson, who, with her late husband Marty, a longtime Reagan adviser, has authored and edited serious books about Reagan. She was offered $5,000 and given just one week to evaluate the manuscript. Having read it, she declined compensation, saying mildly, “I don’t think this manuscript is ready for publication.”

The book’s perfunctory pieties about Reagan’s greatness are inundated by its flood of regurgitated slanders about his supposed lassitude and manipulability. This book is nonsensical history and execrable citizenship, and should come with a warning: “Caution — you are about to enter a no-facts zone.”

© 2015, Washington Post Writers Group