Sunstein: Political gulfs are driven by information cocoons

How do you know what you know? You have firsthand knowledge about many things, including your job, your family and your possessions. But how do you know whether George Washington or James Madison really lived, whether matter consists of atoms, whether Bob Dylan wrote "Like a Rolling Stone," or whether Mars and Venus exist?

With respect to innumerable issues, including political ones, most of what we know is what we learn from other people.

By itself, that is inevitable and nothing to lament. But when we listen mostly to people who already agree with us, our pre-existing convictions get fortified, and we start to think that those who disagree with us are evil, dumb or duped. Is it any wonder that our politics are highly polarized, so much that it sometimes seems as if Democrats and Republicans don't merely disagree but live in unfathomably different universes?

A few years ago, I participated in some experiments designed to shed light on how people's political beliefs are formed. My co-authors and I assembled a number of people into all-liberal and all-conservative groups. We asked the groups to discuss climate change, affirmative action and civil unions for same-sex couples.

We requested group members to state their opinions at three stages. The first occurred before they started to talk, when we recorded their views privately and anonymously. In the second stage, we asked them to discuss the issues with one another and then to reach a group "verdict." In the final stage, we asked people to record their views, after discussion, privately and anonymously.

On all three issues, both liberal and conservative groups became more unified and more extreme after talking to one another -- not only in their public verdicts, but also in their private, anonymous statements.

It's no surprise that before discussions began, the liberal groups were, on all three issues, somewhat more liberal than the conservative groups. What is striking -- and more revealing about our current problems -- is that after liberals spoke only with liberals, and conservatives only with conservatives, the divisions between the two groups grew dramatically.

Why do groups polarize in this way? One reason involves people's concern for their reputations. If you find yourself in a group of people who hate affirmative action, you might be reluctant to say that you like it, and your agreement with the group in a public setting might affect what you say privately.

The more interesting reason involves the exchange of information. In the conservative groups, for example, people tended to offer a number of arguments against affirmative action, and very few in favor of it. Group members learned from what they heard -- and became more confident, more unified and more extreme.

Can anything be done to address this? The most obvious answer is to break out of information cocoons. That's a central goal of the American constitutional system, which was devised to ensure that diverse people would, in fact, speak with one another.

Opponents of the Constitution urged that self-government required homogeneity and that diversity could create paralysis and chaos. By contrast, the defenders of the Constitution -- above all Alexander Hamilton -- thought that diversity could be a creative force and that "the jarring of parties" could be productive, because it would "promote deliberation."

Political conventions are occasions for group polarization. This is by design. But in the best cases, campaigns get people to escape from their information cocoons -- not merely because competing perspectives are available, but because citizens are really listening.

Many of our political convictions are intensely held, especially in an election season. But an appreciation of how we know what we know should help to engender a healthy dose of humility -- making political campaigns far more productive and sensible governance far more likely.