"Common sense" at various times and various places has held that slavery is an excellent institution, that women are the possession of their husbands or fathers, that human sacrifice is an admirable thing, that torture by the authorities is acceptable, that it is right and neccessary to suppress heresy and kill heretics...

Or, for that matter, that there are no moral problems in widespread abortion.

And people who have opposed these things have been seen as holding to "an ideal that is too far from the mainstream".