I pitched in with a supporting comment on this post, where David catches brother Clay in a rare misjudgment.

There is a related piece by Amy Harmon, where she takes the position that the Internet allows people to sit in echo chambers. I disagree with that view, but I cannot express myself as well as Steve Johnson.

However, Harmon does have this priceless quote at the end:

For MoveOn.org, the goal is to mobilize like-minded people to action against the Republican agenda, not to persuade them that it's wrong, said Eli Pariser, the group's campaign director.

"Changing people's minds is overrated," Mr. Pariser said. "Most of the people in this country are with us, and it's a matter of getting them active and getting them informed."

This is so typical of the insulated left, which does live in an echo chamber. In fact, most of the people in the country are not with them, and they really do need to learn to engage in rational debate with those of us on the right.

The Internet is not what causes the echo-chamber mindset. It's the arrogance of Mr. Pariser and his fellow-travelers, which is independent of whatever medium in which they deal.