https://www.lesswrong.com/s/M3TJ2fTCzoQq66NBJ/p/ZQG9cwKbct2L...

When more moderate, reasonable, or relatively skeptical people leave the group, people who remain are, on average, more fanatical and extreme. Which leads to even more extreme viewpoints, which pushes out more and more people who previously might have been acting as a voice of moderation.

> After the [moderate members] escape, the remaining discussions will be between the extreme fanatics on one end and the slightly less extreme fanatics on the other end, with the group consensus somewhere in the “middle.”

So

> This is one reason why it’s important to be prejudiced in favor of tolerating dissent. Wait until substantially after it seems to you justified in ejecting a member from the group, before actually ejecting. If you get rid of the old outliers, the group position will shift, and someone else will become the oddball.