With the rapid erosion of conservative social norms in late 20th century America, the old adage that children should be "seen and not heard" has, in most cases, flown out the window. Now this is a shift I entirely support when looked at out of context. But this change has accompanied--I would say causally--a shift in childhood development. If kids are allowed to demand what they want, and vocalization of opinions is encouraged at an early age, then it follows that society will produce headstrong brats.
The type certainly existed before the erosion of the norm of suppressed and submissive children. However, parental encouragement to speak one's mind at a young age has increased the density and intensity of self-important assholes in contemporary America.
This brings me to the classrooms of the University of Chicago, surely sites of much conceited verbosity and self-righteousness. My project is not to tell haughty first-years to have some humility; I would not presume to have that much influence. Instead, I write in hopes that professors will read this and agree with me. The only thing stopping intelligent but ignorant undergraduates from having classroom humility is the fact that many professors put up with their ramblings. This, not shyness, is the most glaring problem with contemporary discourse in U of C undergraduate courses: students run off at the mouth and professors, in their equanimity, refuse to interrupt or disagree with them. These circumstances have arisen mainly out of a pervasive atmosphere of equality of opinion.
The classroom is not a forum for all opinions. Professors should steer conversations so that they remain on topic. Banal analogies to real life and anecdotes are usually undesirable. Material should be edified through the interplay of intelligent ideas, not through simplification or reification.
Secondly, all the best professors are polemical. Even if a particular student has completed the reading for a particular class, which is questionable in the first place, it is unlikely that the student understands the reading as well as his professor does. I state the obvious because the classroom is often seen as a place where ideas are exchanged and dispersed without regard for erudition.
This is detrimental to both the students and the professors. While the former usually benefit by participation, if they have glaringly incorrect understanding of a text, then the professor would do well to quash them.
Muscles form through tension, by tearing and reforming stronger. The same is true of intellect. A polemical professor, one who is willing not only to play devil's advocate, but also to register his personal disagreement in classroom discussions, better educates his students than a complacent yes-man.