Overthought: Who's in a Bubble?

I'd like to introduce a new recurring feature I am calling "Overthought": it is a chance to briefly present both sides of an argument and share. Some of my thinking about it, without necessarily drawing definitive conclusions.

Today, I'm thinking about the commonly heard complaint, on both sides of the political divide, that their opponents persist in pushing bad policy because they are trapped in an echo chamber where falsehoods and half truths are repeated so often that they are uncritically accepted. Classically, this argument has been made by the left, as it is in this piece by Kevin Drum. A sample:

The Fox cocoon may be good for stirring up the troops, but it's almost certainly not good for the intellectual development of new ideas. And eventually that catches up to you. If modern conservatism is simultaneously politically vigorous but intellectually enervated, Roger Ailes and Rush Limbaugh probably deserve both the credit and the blame.

But lately, I have been hearing more often that liberals are trapped in their own distorted reality. In First Things, R. R. Reno argues that conservatives are the true cosmopolitans because they have to engage with liberal ideas, whereas liberal ideas, especially in the academic setting, are accepted uncritically. Here's the gist:

We’ve all experienced the liberal default to denunciation. Reservations about radical feminism? “Patriarchal.” Criticize multicultural lunacy? “Cultural imperialist.” Question affirmative action? “Racist.” Opposed to same-sex marriage? “Homophobic” or “heterosexist.” Worried that increased taxation will stifle economic growth? “Protecting the rich” and “indifferent to the poor.” The message is that anyone who questions liberal policies is either a bigot or out for himself, and probably both

My loyalties incline me to agree with Reno, but I think the truth is that every tribe has it's non-introspective polemicists who don't engage opposing ideas in good faith. And I also think this is largely a function of location, vocation, and inclination. If you are, say, a New York based artist, you are unlikely to have to rigorously defend liberal assumptions unless you actively seek out conservatives to argue with. Same goes in reverse is you are a pharmaceutical executive in Indiana. So, I am inclined to think that the problem is partially that we can increasingly self-select to surround ourselves with like-minded people, but mostly that our nation is split between two very different philosophies with ever-fewer common assumptions about how the world works.