"However intelligent they are, people who think and act within their niche avoid the irritating presence of ideological foes, but they also forgo one of the preconditions of learning: hearing other sides. Hearing them, that is, in earnest and positive versions, not through the lens of people who don't endorse them. They develop their own positions, tautly and intricately, but can't imagine others'. [...] in the words of John Stuart Mill: "They have never thrown themselves into the mental positions of those who think differently from them." A paradoxical effect sets in. The more secure they feel, the more limited their horizons and the more parochial their outlook."
Mark Bauerlein, The Dumbest Generation: How the Digital Age Stupefies Young Americans and Jeopardizes our future, Tarcher/Penguin, 2008, s 221-22