Little Green Men from Afar • (1976) • essay by L. Sprague de Camp: "Also, more and more find it possible, by easy travel and communication, to confine their social lives to those who share their own outlooks and prejudices. Wherever they go, they seek out others of their own peculiar views, since most folk prefer having their existing beliefs confirmed to having them refuted. In such a limited milieu, the most bizarre ideas can be solemnly embraced, because the cultists, seeing only one another outside of working hours, are never forced to consider other points of view. Hence a leader, if he can isolate his followers long enough, can convince them that the moon is made of green cheese. Since they never hear him contradicted, they believe it indefinitely. Thus contemporary society tends to become more and more subdivided into small, exclusive, mentally self-isolated groups. Each has its own version of the True Faith and never listens to any other.
What can be done about this? Something, but not a great deal. If one is in academe, one can drill one's students in the criteria for judging a statement... One can warn one's students against the stigmata of the charlatan: arrogance, garrulity, appeals to emotion, authoritarianism, incomprehensible language, conviction of his own grandeur and persecution, and certainty that those who reject his ideas are scoundrels or madmen."