@cstross I was unfamiliar with the concept of "egregore", so my opinion isn't worth much. But after a quick search, I would say "sort of, but not really." It sounds like both of them can affect the thinking and actions of a group, but *if I'm not mistaken* , the egregore actually becomes manifest, where-as it's doubtful that Roko's Basilisk will become real from the mere act of thinking about it. The Basilisk either does/will exist or it doesn't/won't, and thinking about it won't change that.