As I reflected back on the works of Ken Wilber recently, a thought occurred to me: man, that guy must have done a lot of drugs.

I don’t recall Wilber ever saying anything about drugs in his work one way or the other. Given that he wrote most of his work under the restrictive régime of the late-20th-century US, that shouldn’t be a surprise; caution is valuable. Yet he is an American baby boomer deeply interested in spirituality and mysticism; that is the sort of profile that leads one to expect significant experimentation with psychoactive substances.

But more importantly than his demographic: Wilber’s philosophy is very much the sort of philosophy one would expect from someone who had had profound drug-induced mystical experiences. A theme throughout Wilber’s work is the importance of experience to knowledge, a view that Wilber’s late work comes to call “radical empiricism”. He claims throughout his work that the essentials of premodern wisdom traditions – Platonism, Buddhism, Christianity – are to be found in mystical experiences, and in replicable practices that lead up to those. Some years ago I wrote an article debunking this claim: I don’t think that a reasonable historian can look at the evidence we have of Confucius or Moses or Jesus or Zhiyi (Chih-i) and still say that the essentials of their teachings come from replicable experiences. (We could reasonably say that Moses at the burning bush was having a mystical experience, but it was not in any way replicable.)