I think you want the ingroup to seem “normal”, but I think there is selection pressure on groups for their “normal” seeming beliefs to require costly signals. (Or, in general, group cohesion is stronger when group membership requires costly signals. One such type of signal is What Group Members Believe. If your social games depend on that particular input, your beliefs are going to be weird enough to distinguish the ingroup from the outgroup)
I think you want the ingroup to seem “normal”, but I think there is selection pressure on groups for their “normal” seeming beliefs to require costly signals. (Or, in general, group cohesion is stronger when group membership requires costly signals. One such type of signal is What Group Members Believe. If your social games depend on that particular input, your beliefs are going to be weird enough to distinguish the ingroup from the outgroup)
(A lot of my thinking is downstream of this post by Scott from awhile back)