It’s conventional wisdom that groups generate ideas and plans more moderate than those of individuals. Groups and discussion encourage compromise, smooth out extremes, and guarantee moderation. It is also one of the unspoken assumptions of facilitation and group-oriented scenario work. Facilitation and scenario-building, the thinking goes, builds a sense of collective spirit by helping groups develop a shared vision of the future.

But Cass Sunstein’s new book, Going to Extremes, challenges these assumptions. As Slate’s Christopher Caldwell explains in a review,

Going to Extremes… finds that sitting people down to deliberate does not necessarily lead them to compromise or to converge on their mean opinion. They tend to radicalize in the direction of whatever bias they had to begin with. Teams of doctors, deciding collectively, are more likely to support the “extreme” strategy of heroic efforts to save terminally ill patents than the average individual doctor among them. Juries tend to vote, after discussion, for much more “extreme” monetary awards than the average individual juror among them would. Talking things over isn’t necessarily wrong. But it doesn’t lead reliably to moderation, either….

Much of Sunstein’s evidence about how people drift to extremes comes from his studies of groups that already have a bias to begin with. Individual Democrats and Republicans on three-judge panels cast more “extreme” votes when they are in the majority than when they are not. A group of conservative Republicans in Colorado Springs will move sharply rightward when they discuss global warming among themselves, and a group of liberal Democrats from Boulder will move sharply leftward.

These homogeneous groups are not the special cases they would appear. They tell us something about what happens in more heterogeneous groups, too. If you bring the two clashing sides together, they don’t find middle ground any more than like-minded people do. Each side digs in. If you give “a set of balanced, substantive readings” to a group that is at loggerheads over abortion or affirmative action, Sunstein shows, each side simply mines the readings for support of its own position. Ideology, it turns out, is not just a matter of opinions or positions—it is a predisposition to receive some kinds of evidence and not others. Compounding the problem, certain kinds of extremist arguments have an “automatic rhetorical advantage” in deliberation. Me, too, but less is harder to rally behind than In for a penny, in for a pound.

The question this raises is whether the facilitation methods that futurists use tend to encourage moderation, or exacerbate this problem. Do scenarios tend to force people to think together, and recognize that complex issues can’t be solved through simple means? Or does the intellectual and imaginative freedom that thinking about the future provides encourage groups to project their own extremes?

Add this to the list of insights from psychology– along with the work of Daniel Gilbert, Daniel Kahnemann, Philip Tetlock, et al– that futurists need to consider when thinking about how to improve their work.