The irony of calling Scott Alexander "deeply ignorant" :)
Human challenge trials. Hundreds of thousands of dead later, and we're still using statistics to answer questions like "is Omicron ignoring immunity", instead of answering them definitely in a few days with an absolute minimum of risk. I'd volunteer for that, btw, so would literally millions. But it's just not inside the Overton window. This isn't wisdom or caution. It's plain cowardice.