Don Boudreaux has a silly piece today defending the Great Barrington Declaration and AIER by acting as the arguments against the GBD are ad hominem.
There's been considerable direct takedowns of the GBD from epidemiologists, showing how it is impractical and ineffective to segregate so many people, that the authors don't offer substantive ways to do their focused protection, and that the authors don't suggest the most effective tools.
Those aren't ad hominem attacks.
In any case ad hominem argumentation isn't an inherent logical fallacy. It is relevant to show the GBD authors' views outside the document. It is relevant to show they have a consistent pattern of endorsing views of the virus that downplay its severity, nature of its spread, and means to mitigate it. And it is relevant to show they have not adjusted their views when they have been proven wrong. As Carl Bergstrom noted, it is okay to have wrong predictions. Everybody has been wrong about some element of this virus. What matters is the behavior after the fact and adjusting your views with the new information. All three GBD authors have instead doubled down.
The piece is hilarious. As it pompously speaks about how one should not engage in logical fallacies, it does precisely that throughout the piece.
He brings up Fauci's early comments on HIV/AIDS in 1983 when much was still not known about its transmission. He misleadingly claims Neil Ferguson predicted huge deaths from Mad Cow disease, bird Flu, and Swine Flu without acknowledging, the context of his comments, the actual point estimates and conditions of his predictions, and lower bounds of his modelling.
He argues that the three authors are world-renowned scientists, as though we can't bring up their views and claims on the coronavirus. He argues that the declaration was signed by other credible scientists, failing to acknowledge that many of the signatories are not relevant issue experts, many were fake, and many were non-experts.
And then he argues we can't attack AIER to impugn the GBD through guilt by association.
But motives and associations are important. Jay Bhattacharya's much maligned antibody survey study was used in an op-ed piece by his co-author, who failed to disclose he was a co-author, to argue against the policy responses to the pandemic. Bhattacharya's wife recruited her friends for the serological survey in an explicit call to argue for early reopening.
Kulldorff and Bhattacharya have penned repeated op-eds downplaying testing, tracing, asymptomatic transmission, child transmission, masks, and arguing for reopening.
Boudreaux would like us to think the GBD and AIER have an arms length relationship, but the GBD authors have repeatedly endorsed and shared the views of AIER's staff. Even in the same piece, Boudreaux talks up AIER's efforts to organize and host the declaration.