Brendan Borrell’s recently published New York Times article, The Psychedelic Evangelist, about Johns Hopkins University’s late pioneering researcher Roland Griffiths, joins a series of blog posts, news articles, and academic papers discussing problematic aspects of psychedelic science. Some of these concern personal misconduct, but others are rooted much deeper. Psychedelics bring together human psychology and chemical compounds, science, metaphysics, and cultures. They are explored by pharmacologists and philosophers, anthropologists and psychiatrists, all trying to study what’s in a psychedelic, each with their own vocabulary and worldview. Some of the problems that arise from psychedelic research represent old schisms between the sciences and the humanities and questions about knowledge as a whole. Here too, psychedelics seem to have a revealing effect, exposing our own thinking mechanisms.