I had a look at the frontpage co-signers of the the Great Barrington Declaration and found I actually know several of them, either personally or via colleagues who work with them. I wouldn’t fault their professionalism too readily. (In particular Lisa White, Professor of Modelling and Epidemiology at Oxford University, is very sharp, sincere and thorough.) The problem isn’t with their expertise in epidemiology or related branches of medicine; it’s with their lack of expertise in public health policy, sociology and behavioural science. The declaration makes a definitive judgement about the optimum strategy for protecting public health, which depends on many more pragmatic factors than medical science.
In the early days of this pandemic, before the first UK lockdown was proposed, I advocated similar action: i.e. shielding and supporting the vulnerable and letting the virus spread naturally through the healthy population. But I didn’t think it through well enough. Some of my elderly relatives were appalled at the proposal to impose severe restrictions on them while the rest of society continued with their normal lives relatively unimpeded. Extended families would have to be separated according to age and underlying health conditions (many of which would be difficult to identify reliably). Mandatory imposition would constitute a selective disregard of individual freedoms and human rights. It would be a very hard sell. Moreover, it may not even be viable at all, as we know so little about acquired herd immunity to each strain of the virus.
Interestingly, some of its most sanguine supporters on the internet hold views contradictory to the underlying science: e.g. that there is no virus, that testing is unreliable, that the wrong therapies are being applied, that the concept of herd immunity is flawed, and so on. I think they only mention it as a way to cast doubt on scientific consensus and public health policy, or to undermine the rationale for social distancing and lockdown measures. It’s important to keep the scientific consensus and the public health policies separate, because they depend on different domains of reasoning – matters of fact vs matters of concern (aka the ‘is/ought’ dichotomy). Imho, the signatories to the Great Barrington Declaration should confine themselves to telling us facts about the virus and how it spreads, without insisting on a plan of action to tackle it.