This article expands on a topic from our recent news digest. We're exploring two conflicting studies with Dr Peter Sjöstedt-Hughes, a Philosopher of Mind and Metaphysics, who shared his perspective on what they mean for our understanding of the mind.
The conversation around psychoactive drugs is getting complicated. One report suggests psychedelics can instill a lasting sense of purpose from a single experience. The next warns that high-potency cannabis is fueling psychiatric risk. It feels like a contradiction. How can altering our brain chemistry be both a path to existential fulfillment and a fast track to mental instability?
That's why we spoke with Dr. Peter Sjöstedt-Hughes, a Philosopher of Mind and Metaphysics. He lectures at the University of Exeter, where he is a lead on the postgraduate courses in Psychedelics: Mind, Medicine, and Culture.
The idea that one powerful trip could overhaul a person’s life sounds like a spiritual fantasy, yet new research suggests it’s happening. A recent study found that psychedelic experiences can provide a deep, sustained sense of meaning for years, long after the substance has left the body. This cuts against the modern assumption that meaning is the slow work of reflection and cultural learning.
But for Dr. Sjöstedt-Hughes, this phenomenon isn't new. He sees these modern accounts echoing historical conversions, people whose lives were upended by a single, definitive insight.
“There are historical accounts of single, significant experiences that have been noted to have life-changing effects: sudden conversion experiences such as that of St Paul, Constantine, and St Augustine, to name a few Christian examples. Yet we also have such examples in psychedelia – for instance, both Humphry Davy and William James were converted to the truth of Idealism (that all is mind) through nitrous oxide.“
The pattern continues into the 20th century with neurophilosopher John Smythies’ work with Aldous Huxley on Outsight stemming from a similar breakthrough. But the most powerful proof, he offers, comes from the unlikeliest of sources: A. J. Ayer, the famously skeptical Oxford philosopher who built his career on rejecting metaphysics. Even he, after a psychedelic-like experience, was forced to concede that "perhaps death is not the end after all."
This connection, he argues, is a principle that should be central to modern therapeutic practice. In his 2023 paper, he made the case that "the metaphysics of consciousness should be integrated into psychedelic therapy" precisely because these experiences can foster "long-term, deeper senses of meaning about self, others, and world, and thus enhance mental health."
So how does it work? Dr. Sjöstedt-Hughes suggests it’s less about unlocking something and more about redefining the very ground on which we stand. He argues that our sense of meaning rests on unspoken beliefs about reality—our personal metaphysics. "The West has generally rejected teleology... over the last few hundred years," he explains, suggesting this is a plausible factor in our modern anxieties, from nihilism to the so-called ‘meaning crisis.’
The solution, then, lies in rewriting those foundational beliefs. "Meaning is based on metaphysics, and psychedelics may alter metaphysics, thus meaning," Dr. Sjöstedt-Hughes says, concluding with a memorable line: "I always say that psychedelics are a gateway drug to metaphysics."
But this leaves the darker side of the equation. Are existential growth and psychic destabilization opposites? Or are they two expressions of the same fragile relationship between mind and chemistry?
Dr. Peter Sjöstedt-Hughes sees them as two outcomes of the same volatile process. The substance isn't inherently constructive or destructive; it’s a catalyst. For some people, he notes, philosophy itself can be a dangerous substance. "Questioning the very substance of reality can lead to both states of exuberance and existential dread," he says.
He offers the concept of Idealism—the very same philosophy he mentioned earlier—as a perfect example. For one person, it can be "a magical new way of relating to reality," while for another, it's nothing short of "a terror of derealization." It’s a razor’s edge that exists with or without drugs. "And, as we saw, Idealism can be induced by philosophy or psychedelia, by McTaggart or mescaline," he adds.
The line between revelation and a breakdown is, perhaps, deceptively thin. The chemical is just a key. Whether it opens a door to a cathedral of meaning or a room of terrifying chaos has as much to do with the person turning it as the key itself. As we map these chemical frontiers, the terrain that matters most is the one within.
Dr. Peter Sjöstedt-Hughes is a Philosopher of Mind and Metaphysics who specializes in fields pertaining to panpsychism, pantheism, mental causation, and altered states of consciousness through thinkers such as Whitehead, Spinoza, Nietzsche, and Bergson. Peter is a lecturer at The University of Exeter, where he is a lead on the postgraduate courses in Psychedelics: Mind, Medicine, and Culture. He is co-director of Europe’s largest psychedelics conference, Breaking Convention, and the author of Noumenautics (2015), Modes of Sentience (2021), co-editor and contributor of Bloomsbury’s Philosophy and Psychedelics (2022) and Strange Attractor’s Breaking Convention: Musings and Meditations on Psychedelia (2025) – alongside numerous articles. As well as the TEDx Talker on ‘psychedelics and consciousness’, and speaker on the BBC’s show ‘The Trip’, Peter is an inspiration to the recreation of inhuman philosopher Marvel Superhero, Karnak.