Psychedelic experiences famously produce revelations, insight moments that feel intensely truthful and important. However, writes Henry Straughan, we should treat these insights with scepticism: the sense of certainty they bring is not a guarantee of truth. Instead of making new dogmatic claims about reality, the value of psychedelic experiences lies in sceptical openness to different ways of thinking and in understanding the limitations of our own minds.

Psychedelic trips abound in apparent insights. Drugs such as LSD, psilocybin, and mescaline enable the fluid thinking required for solutions to intractable mathematical or technical problems. They produce flashes of creativity that spark musical genius and lead to therapeutic breakthroughs into personal history and present psyche. Of particular philosophical interest, however, is the way psychedelics purport to produce ethical and metaphysical insights into the nature of reality and even religious experiences of the divine itself. These “insight moments” are marked by a peculiarly intense phenomenology: one has the sense of something profound being revealed, of at last understanding the ways things are. Put simply, it is a feeling of truth.