This reminds me of a part of Taleb's "The Black Swan", which I've been rereading in light of recent events. In it, Taleb describes how a process or event can b

This reminds me of a part of Taleb's "The Black Swan", which I've been rereading in light of recent events. In it, Taleb describes how a process or event can be misperceived as strengthening those who go through it, when actually it weakens all of them, killing some. His example is submitting a cohort of rats to radiation. As they are subjected to higher and higher levels of radiation, more will die, the ones who are naturally stronger will survive. Our cohort will appear stronger and stronger as the radiation increases and the dead drop out of the group. But crucially, all will have been weaker after the radiation than before it. But since we observed a stronger group the more we increased the radiation, we may say that it "hardened" them, in the sense of "that which doesn't kill one makes one stronger".