Another example: The current elite anxiety about Russia’s hand in the West’s populist disturbances, which reached a particularly hysterical pitch with the pre-Mueller report collusion coverage, is a classic example of how conspiracy theories find a purchase in the supposedly sensible center — in this case, because their narrative conveniently explains a cascade of elite failures by blaming populism on Russian hackers, moneymen and bots.

And yet: Every conservative who rolls her or his eyes at the “Russia hoax” is in danger of dismissing the reality that there is a Russian plot against the West — an organized effort to use hacks, bots and rubles to sow discord in the United States and Western Europe. This effort is far weaker and less consequential than the paranoid center believes, it doesn’t involve fanciful “Trump has been a Russian asset since the ’80s” machinations … but it also isn’t something that Rachel Maddow just made up. The hysteria is overdrawn and paranoid; even so, the Russian conspiracy is real.

A third example: Marianne Williamson’s long-shot candidacy for the Democratic nomination has elevated the holistic-crunchy critique of modern medicine, which often shades into a conspiratorial view that a dark corporate alliance is actively conspiring against American health, that the medical establishment is consciously lying to patients about what might make them well or sick. Because this narrative has given anti-vaccine fervor a huge boost, there’s understandable desire among anti-conspiracists to hold the line against anything that seems like a crankish or quackish criticism of the medical consensus.

But if you aren’t somewhat paranoid about how often corporations cover up the dangers of their products, and somewhat paranoid about how drug companies in particular influence the medical consensus and encourage overprescription — well, then I have an opioid crisis you might be interested in reading about. You don’t need the centralized conspiracy to get a big medical wrong turn; all it takes is the right convergence of financial incentives with institutional groupthink. Which makes it important to keep an open mind about medical issues that are genuinely unsettled, even if the people raising questions seem prone to conspiracy-think. The medical consensus is generally a better guide than crankishness; even so, the tendency of cranks to predict medical scandals before they’re recognized is real.