There's the Asch conformity experiments, where people went along with the group with no overt pressure and with nothing at stake: http://psychology.about.com

There's the Asch conformity experiments, where people went along with the group with no overt pressure and with nothing at stake: http://psychology.about.com/od/classicpsychologystudies/p/conformity.htm The Milgram experiments on obedience to authority are also relevant. 65% of subjects went along with what amounted to torture of another person: http://en.wikipedia.org/wiki/Milgram_experiment While these experiments weren't about the spread of ideas, conformity and obedience are certainly at work for the vast majority that simply repeat what they hear. You can have a perfectly sound, logical case, even with physical evidence and many will not trust their own judgement if its contradicted by an authority. But it sort of has to work this way. There have to be followers if there are to be leaders and leaders are necessary if groups are to compete with each other, which was the case even before modern humans showed up.