This is an extremely dangerous conception of truth. Even when practically everyone believed that the sun revolved around the earth, the one guy that didn't was

This is an extremely dangerous conception of truth. Even when practically everyone believed that the sun revolved around the earth, the one guy that didn't was still correct. Yet he was pretty likely to be oppressed or killed for having heterodox views and had best keep his mouth shut. I'm sure there are many popular ideas now that are believed by a supermajority (or even 95%+) of the population which are actually incorrect, although I can't say what the correct ideas are or whether they will ever become popular.