"Over my decades, I have seen numerous ideas go from socially intolerable & indefensible, to practically obligatory & untouchable (or vice versa). Seriously, th

"Over my decades, I have seen numerous ideas go from socially intolerable & indefensible, to practically obligatory & untouchable (or vice versa). Seriously, there are things today that can't be opposed in the slightest without threatening one's standing or career, which not long ago were universally anathema that couldn't be defended." Which things, out of curiosity?