0/ Thread on how mass-media-induced fear of COVID irrationally transformed our priors.

I have talked a lot about the mass hysteria that was created...


This thread gets more at the many facets of common sense it wrecked.


If, prior to evidence, your brain has deemed COVID to be totally unlike a typical cold virus, then your brain has undermined the proper prior probability settings.

That wreaks havoc on rational belief. And especially on “common sense.”

It shifts the burden of evidence such that

~ Every normal baseline expected thing about a cold virus now has to be proved to an unreasonably high standard.

~ And every hypothesis about it being especially bad in some respect barely requires support.

That’s why COVID is the dozen-headed hydra, with a new (or yesterday’s) danger each day, no matter how many heads have been cut off.

When priors work normally, all those dozens of heads don’t have to be fought off with every new data point.

THAT’s common sense.

Here is a partial list of the hydra heads for COVID, and whose off-the-rails priors led to the wrong baseline expectation.

(a) its infection fatality rate (IFR) is super high

(b) there are few asymptomatics (and so IFR will be roughly the very high early CFR values)

(c) transmission is unprecedentedly high

(d) asymptomatics can spread it

(e) it’s disproportionately risky for the young

(f) no one is safe, comorbidities or no

(g) it will hit the entire population (and so let’s multiply CFR by total population and see the total expected deaths)

(h) immunity doesn’t apply

(i) herd immunity can’t happen

(j) it leaves you with chronic health issues

(k) seasonality does not apply (i.e., the epidemic doesn’t have a tendency to come, and go, at a typical time of year, like almost all other viruses do)

(l) it goes away only via intervention policies (lockdowns, masks, etc.)

(m) all variation in epidemic severity is due to intervention policy

(n) a vaccine will be easy to build soon, and super effective

The same hysteria that led to radically uncalibrated priors for COVID also created ridiculous priors concerning lockdowns, which bizarrely were suddenly treated as super obvious common sense. https://twitter.com/MarkChangizi/status/1254796958964858882?s=20

Masks, too. Suddenly the idea of forcing an entire populace to cover their humanity and expressions, and compromise their breathing, for long periods (e.g., workers) was common sense. https://twitter.com/MarkChangizi/status/1278298284642021379?s=20

Many point to case curves high in the U.S. relative to EU, despite similar mortality curves. The presumption should be that “same mortality curves implies same *true* case curves,” bad priors lead to “something utterly different is happening!” https://twitter.com/MarkChangizi/status/1284928893225521154?s=20

And these malformed priors also led to regular, non-authoritarian, folk scrambling to out-China China.

They forgot that this is not SimCity, and they can’t play with the dials without ethical and unintended consequences. https://twitter.com/MarkChangizi/status/1252977496699609088?s=20
13/ end

Common sense and the priors undergirding it are the topic of one of my early research directions. Here’s an excerpt from my Brain from 25000 Feet on a grand theory of prior probabilities and the foundations of induction (with @DrTimBarber).

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