The answer to that question should be always "nothing!" You have chosen examples in jest, to show how some assertions are unbelievable/silly; but other assertio

The answer to that question should be always "nothing!" You have chosen examples in jest, to show how some assertions are unbelievable/silly; but other assertions, that you or I might find almost as silly are taken seriously (or were taken so until recently), e.g. "Do blacks/women/(other stigmatized group) have equal intelligence as man?", "Should we kill/neuter people with serious psychological illness", "Should we perform lobotomies". Lack of discussion is never a good sign.