Why Ordinary People Did It

In practice

One documented institutional failure reconstructed in full: the roles assigned and what they authorized, the norm that made objection costly, the authority whose instruction was proximate and whose responsibility was distant, the unanimity that suppressed the first dissent, the anonymity that lowered the threshold, and the diffusion that left no one holding the decision. Ends by naming the one intervention at each stage that the evidence says would have interrupted it.