We know, for example, that Trump’s call for an early end to the economic lockdown was inspired in part by the writings of Richard Epstein, a conservative legal scholar who decided that he understands epidemiology better than the epidemiologists and confidently predicted that Covid-19 would kill no more than 500 people. (It’s currently killing four times that many every day.)

Or consider how Fox News responded to the unwillingness of Dr. Anthony Fauci to do what it wanted, and support an early reopening of the economy. To provide an alternative view, the network turned to … Dr. Phil, whose expertise, if he has one, is in pop psychology.

Now, much of this is familiar to anyone who has followed the debate, such as it is, over climate change. Faced with the overwhelming scientific consensus that man-made climate change is real and frightening, the right has long promoted the contrarian views of a handful of quacks — some with actual scientific credentials, but generally in fields other than climate science, and with a shared unwillingness to accept evidence that challenges their preconceptions. And there’s a strong overlap between organizations that promote climate denial and those that promoted virus denial.

But why is there such a close alliance between modern conservatism and quackery? One answer is that a political movement that demands absolute loyalty considers quacks more reliable than genuine experts, even if those experts currently support the movement’s policies.

As I’ve noted in the past, there are quite a few serious economists who also happen to be conservative, but they have been largely frozen out by the G.O.P. in favor of people like Moore. Why? Because serious economists might turn out to have principles, rejecting outlandish policy claims or changing their views in the face of evidence. And we can’t have that.

Another answer is that the modern right is driven in large part by the grievances of white men who don’t feel that they’re getting the respect they believe they deserve, and Fox-fueled hostility to “elites” who claim to know more than guys in diners — which, on technical subjects like epidemiology, they do — is a key part of the movement.

Finally, there has historically been a strong association between right-wing extremism and grifting, including snake-oil and get-rich-quick schemes. Alex Jones may attract an audience by peddling conspiracy theories, but he makes money by selling nutritional supplements, which he is now claiming offer protection against the coronavirus.