Yes, belief is social. What our in-group believes is way more important for what we believe and how we change our minds than one might think.
Like, if someone is a flat-earther, changing their mind with facts and figures isn’t going to be very effective. Their in-group believes otherwise. And when you come at them with contrary facts, the brain treats it similarly to a physical threat to its survival. In ancient, pre-history humans, this might have been an advantage. The guy who didn’t go along with the group got left for dead. Unfortunately, modern life is more complicated.
If we want to make the world better, we should probably focus on breaking up shitty ingroups (eg: fox news, the gop) and fostering groups that are worthwhile (I can’t think of an unassailable group, which may indicate another problem)
An unassailable group seems impossible given that there shitty people out there, who if they join such a group, immediately mean that someone is not necessarily trustworthy because of merely being a part of said group. Even a belief that one’s group is an unassailable paragon seems problematic as if one truly thinks that one’s group is unassailable, then any accusation of wrongdoing by an outsider towards a member will get dismissed, and you could get a situation like some religious groups get with priests or others that they see as inherently good and trustworthy, where when an abusive person inevitably attains that status, allegations against them are dismissed and covered up.
