Almost everyone takes this for granted, but it still freaks me out: Audiences in presidential debates applaud just because a candidate says something they agree with... Why not just hold up big signs that say: "TELL US WHAT WE WANT TO HEAR"?
Keep this in mind the next time someone blames politicians for the low quality of political dialogue. The hard truth is that politicians are just responding to the perverse incentives that the people give them.
Democracy is only as bad as the demos. Unfortunately, at present we suck. Not intrinsically; I don't think the general public is irredeemably stupid, or anything like that. It's a simple attitude problem. Most people, it seems, don't care about honest inquiry. Our social norms encourage pandering, close-mindedness, and intellectual dishonesty. It's shameful.
What can be done? Two things, I suppose:
(1) Model good practice. "Be the change you want to see in the world," as Gandhi put it.
(2) Apply social pressure to create better norms. Praise intellectual virtues, and scorn those who wallow in cognitive vice.