JIM MEIGS ON Conspiracies All the Way Down: The 9/11 Truther movement was a harbinger of today’s paranoid politics.

Most versions of the idea suggested the real perpetrator was a cabal that included Bush, Cheney, oil companies, military contractors, the Mossad, and other malefactors, all conspiring to launch wars in the Middle East. In the faux-insider jargon that conspiracists love, it was a “false-flag operation.” The notion meshed perfectly with the Howard Zinn view of history in which all evils in the world can be traced back to some original sin involving U.S. policy. (True to form, Zinn offered a supportive blurb for one of the most popular books promoting these 9/11 claims, David Ray Griffin’s The New Pearl Harbor.) Such theories, avidly discussed on left-wing websites and in the alternative press, rarely surfaced in the American mainstream media. But here was a full-page ad proclaiming these ideas in the New York Times.

The book’s claims sounded doubtful but also fairly easy to confirm or disprove. How hot does jet fuel burn? How big a hole would a Boeing 757 make in a reinforced concrete building? These questions were very much in the Popular Mechanics wheelhouse. Every conspiracy theory ultimately rests on a handful of claims about physical reality. What if we put together a team of reporters and simply fact-checked the most common claims made by 9/11 conspiracy theorists? If the factual assertions were wrong, then the elaborate theories built on them were wrong, too. On the other hand, if there were even a grain of truth in any of these claims, well, what could be more vital to investigate?

We assigned eight reporters to the inquiry. Popular Mechanics executive editor David Dunbar led the project, making sure to keep it focused on technical questions and rigorously non-political. For the next few weeks, our reporters interviewed experts, pored over documents, and talked with eyewitnesses. In every case, they found that the conspiracy advocates’ claims were based on evidence that was inaccurate, misinterpreted, or deliberately falsified. For example, it is true that jet fuel burns at 1,100 degrees Celsius, while steel melts at about 1,500 degrees Celsius. But, as our sources explained, a steel beam can lose half its strength at temperatures as low as 600 degrees. A number of in-depth engineering studies provide detailed accounts of how the impacts of the planes, combined with heat from fires, eventually weakened the structures to the point where collapse was inevitable.

The claim that the hole in the Pentagon wasn’t big enough to have been made by a 757 rested on similarly flawed evidence: the airplane’s wings were simply sheared off by the building’s thick concrete walls. In any event, investigators found wreckage from the fuselage and remains of the passengers, crew, and hijackers deep inside the Pentagon, and they subjected this evidence to forensic examination. (We interviewed some of the people involved in this horrific task.) And so it went. Every conspiracy claim crumbled when subjected to the slightest factual scrutiny. In every case, we found, the theorists clung to slender reeds of misinformation, while scorning mountains of evidence supporting the mainstream view.

Well, Howard Zinn. Plus:

When Popular Mechanics waded into the discussion, some on the mainstream left were bemused. We must have some kind of political agenda. Were we trying to defend the Bush White House? Why would we want to help them? This was the moment I realized journalism was changing. The evenhanded search for truth—rarely achieved in practice—was fading even as a journalistic aspiration. Now every set of facts must serve a political purpose. If it wasn’t helpful to the Left, it must be helpful to the Right. Where journalists once obsessed over the accuracy of facts, now they worried more about their utility. If some piece of information helps the wrong sorts of people, perhaps it’s best left unpublished. Last year, we saw this logic carried to a new extreme, when virtually all major media outlets refused to cover the revelations contained in Hunter Biden’s laptop, or to explore evidence that Covid-19 might have escaped from a Wuhan, China lab.

So, with a few exceptions, the media mostly gave the 9/11 Truthers a pass. That was one factor helping this minor cult become a mass movement.

Once the press becomes a nest of partisan shills instead of an at least somewhat trusted intermediary, conspiracy theories thrive. Or it might be better to say that as conspiracies proliferate, conspiracy theories thrive.