Are “Group Hallucinations” Possible? The Case of Mary.

Several people have asked me about my claim that “group hallucinations” are possible – that is, that a “vision” can be seen by many people at once. It seems counter-intuitive: aren’t hallucinations by definition the inner workings of a person’s mind? How can more than one person have the same hallucination at the same time?

Well, I’m not sure how that works, psychologically. My guess is that there is a strong sociological component as well – i.e., that something weird is seen by a number of p...