Philosophy and psychedelics might seem like obvious siblings, but they have been estranged in academic contexts. Thinker and author Chris Letheby has begun to remedy this. An Australian philosopher working closely with neuroscientists and psychologists, his work suggests how a “naturalistic spirituality” can honour both scientific research and the more intangible or mysterious dimensions of psychedelic experiences. 

Chris’s discipline bending book Philosophy of Psychedelics was published by Oxford University Press in 2021. Thinking about the spectacular mysterious of psychedelics while courageously arguing that “the natural world is all there is”, his work appeals to scientists with similar views. But it also presents an invigorating challenge to anyone who wonders about the legitimacy of the insights, revelations, and epiphanies that come from powerful transformative experiences, and to anyone who wonders about the nature of the self as it undergoes intense psychedelic experiences.

I sat down with Chris to learn more about his work.

Jessica Lawson: I’m interested to know how you became a philosopher. Can you tell us the story of what led you into philosophy?

Chris Letheby: Unlike a lot of people, I came to university specifically to study philosophy. Some people stumble into philosophy through taking a chance elective that gets them hooked; I went in knowing that was what I was there to do. I’d had some involvement with two different religions in the first 20 years of my life. I was raised Christian but I gave that away when I was around 10 or 11. Then in my late teens, I had a fairly serious involvement with Tibetan Buddhism – in particular, some rather fundamentalist forms of Tibetan Buddhism, with an elaborate metaphysics and cosmology: not just reincarnation and karma, but heaven and hell realms; an entire, comprehensive worldview.

Later I realised that I was skeptical about this worldview and I found myself adrift. Twice in the first 20 years of my life, I’d been involved in a religion that gives you a metaphysics and an ethics that are intimately connected. The philosopher Owen Flanagan talks about this: you get a story about how things are, and a story about how you should live your live in light of that. Having had that, and then lost it, makes the question very acute – how should I live? The answer to this question is determined by our worldviews – is it a world with a God or no God, with an afterlife or none? These questions led me to philosophy.

Jessica Lawson: I’m also really interested to know about your journey with psychedelics, and the cross-section of philosophy and psychedelics, because it seems like they naturally overlap. Is your journey with psychedelics something that emerged out of philosophy or was it the other way around? 

Chris Letheby: It’s straightforward for me: philosophy came first and psychedelics came second. For a long time, I didn’t admit to having psychedelic experiences publicly, but I have now come out of the ‘psychedelic closet’. I’ve had such experiences and they’ve been important to me. They’ve played a role in both my personal and my professional life. 

I started studying philosophy at 21 and didn’t have many psychedelic experiences until my late twenties. I’d had a longstanding interest in mysticism, but like a lot of people, I was very ignorant about psychedelics. I saw them as simply “hallucinogens”: drugs that make you see things that aren’t there. 

When I was finishing up my Masters and starting my PhD I learned more about the nature of psychedelics and their history, both in Indigenous contexts and psychiatry. In relation to my interest in mysticism, I’d practiced meditation on and off for quite a while, and enjoyed lots of benefits from that, but I’d never experienced radically altered states of consciousness. So the idea that there were drugs that induced mystical experiences under the right conditions with a high degree of reliability absolutely floored me. Not only that, but they seemed to have all this potential, not only for healing and psychiatric problems, but also for helping people find existential meaning. These are philosophical concerns that are dear to my heart.

“The idea that there were drugs that induced mystical experiences under the right conditions with a high degree of reliability absolutely floored me.”

I started my PhD on a more conventional mainstream topic in the philosophy of cognitive science, and it was around this time that I learned more about psychedelics and had some psychedelic experiences. Philosophers of mind have become really interested in unusual mental states as a source of evidence, and yet hardly anyone seemed to be talking about psychedelic experiences. Researchers were studying pathological cases that happen haphazardly, with all sorts of barriers to studying them. And yet there’s these drugs that can safely and reliably induce radically altered consciousness.

There’s a big literature from when psychedelics were used scientifically from the 1950s through to the 1970s, so I wondered: why weren’t philosophers looking at this vast body of evidence? Apart from a few notable exceptions like the German philosopher Thomas Metzinger, who was smuggling psychedelic themes into his work in the 1990s and early 2000s. And so initially that was the focus of my interest: psychedelic experience as a source of evidence for the philosophy of mind.

As things progressed, though, I got really interested in the idea of reconciling the traditional spiritual uses of psychedelics with a naturalistic worldview. This ended up becoming the focus of my research. I realised that typically people fall into one of two camps. There are the people who think psychedelics give you genuine spiritual experiences; these people tend to call the drugs “entheogens”, and to reject philosophical naturalism or materialism. And then there’s the camp of naturalists or materialists who see psychedelics as hallucinogens that distort perception and cognition and don’t give you any real knowledge. They often think of the drugs as “hallucinogens” or “psychotomimetics” – as anti-epistemic by definition. So the middle ground – that that materialism or naturalism is true, but psychedelics still have epistemic and spiritual value – seemed to me to be a really underrepresented and plausible position.

I’ve written about other topics too, such as what psychedelics can tell us about the nature of the self. But ultimately this has been the central theme running through my work – trying to dissolve the tension between philosophical naturalism and what I call the “entheogenic conception” of psychedelics. 

Jessica Lawson: Why do you think psychedelic use has been neglected in the philosophy of cognitive science? Do you think it’s about the availability of quantitative data? Does stigma play a part? It seems like there’s a natural connection between psychedelics and philosophy, and philosophy seems to offer a really ethical way to study psychedelics. You don’t have to go through all the things that people running clinical trials do, because they’re dealing with humans rather than ideas.

Chris Letheby: Yeah, that’s one thing that makes my life as a psychedelic researcher easier: I don’t need that much funding. I don’t have to get ethics approvals. I don’t have to score drugs! I’ve got a pretty good gig as far as psychedelic researchers go – fewer obstacles to overcome. But then of course I don’t have the immense privilege of being on the front line with people and stewarding them through these incredible experiences.

As far as stigma goes: for a long time, there was this idea that drugs are just bad and psychedelics are especially bad. That drug war propaganda has permeated our society and philosophers, who are supposed to be specialists in critical thinking, are not immune. I think our training does make us good at questioning established dogmas, but we’re only human and we have our blind spots like everyone. So I think in those decades from the seventies through to the noughties, probably that drug war propaganda was playing a role.

Still, that doesn’t answer the question: why didn’t academic philosophers take much of an interest in the first wave of psychedelic science during the 50s and 60s? I think part of the answer is that philosophy then just wasn’t as interdisciplinary as it is now. It’s often been remarked that the separation of philosophy from the natural and social sciences is a modern phenomenon. Since the 1970s we’ve seen a move towards greater interdisciplinarity, and philosophers draw a lot more on scientific evidence. The disciplinary culture of philosophy wasn’t really set up for it during the first wave of psychedelic science.

Ignorance and amnesia have also played a role – for a very long time the history of psychedelics in medicine didn’t get taught to medical students and psychiatric trainees. David Nichols wrote about this and commented that there’s an entire generation of medical professionals who know nothing about these drugs, except that they’re subject to the strictest legal controls possible.

What I call the hallucinogenic or psychotomimetic conception of psychedelics has been very prevalent in philosophy. You find the term “hallucinogen” a lot in the philosophy of perception. People talk about hypothetical cases in which someone has “taken a hallucinogen” and therefore lost touch with reality. So for a long time there has been this perception among philosophers that the principal effects of psychedelics are perceptual, the main thing they do is make you hallucinate, and therefore they’re anti-epistemic. The main thing they do is make you lose touch with the world, and maybe become irrational. And if there’s anything philosophers have a horror of, it’s the irrational. So the concern that I develop in my work, that runs through nearly all of it, is a quintessential philosopher’s concern: do psychedelics make people irrational? Do they give people who use them false or unwarranted beliefs about reality?

Jessica Lawson: There are theories that psychedelics have been administered secretly and gatekept in a ritualistic way by different cultures and religious groups. Do you think that could be a part of why they’ve been used underground for so long? The Eleusinian mysteries, for example?  

Chris Letheby: I’d be open to hearing any evidence. I’m not a historian. I tend to find the standard stories that get told fairly plausible – that there was a war on drugs, which was part of broader social and political currents – there were certain forces and ideas that the drugs unleashed that posed threats to the established order. And you can talk about this as some people do in terms of Apollonian and Dionysian currents in society – that psychedelics unleashed the Dionysian wave of chaos and then the Apollonian forces of order needed to push back against that… But not in terms of any kind of deliberate or conscious conspiracy, just in terms of how these cultural currents work.

I’m reading Matthew Oram’s new book The Trials of Psychedelic Therapy. His argument, as I understand it, is that the reason psychedelic therapy research stopped was not actually to do with the drug war so much, or the broader social and political currents, but rather internal scientific issues. He shows that funded psychedelic research continued for quite a while after the banning of LSD. So in fact the research wasn’t actively suppressed – the Spring Grove research program with LSD and other substances still went on until 1976 or thereabouts. Oram argues that the research struggled to demonstrate that it worked, in part because of the methodological standards of the double blind. Randomised controlled trials had been introduced around the 1950s as the gold standard of evidence in in pharmacology. And it’s very hard to meet those evidential standards with psychedelics because you can’t maintain blinding: people know if they’ve had a psychedelic or a placebo, most of the time. Oram argues psychedelic therapy advocates couldn’t generate evidence that would convince everyone and that would satisfy the methodological standards that had been established in psychiatry.

The other thing I think we shouldn’t forget is that there are real risks, and there were real casualties, and there was a certain amount of genuine concern about safety too.

Jessica Lawson: What were your major findings from your recent research? 

Chris Letheby: The main idea of my book concerns naturalism and the entheogenic conception of psychedelics. The main idea of the book is that they can be reconciled. A lot of people think that if you take psychedelic experiences seriously and think that they have epistemic and spiritual value, then you must be a non-naturalist – to believe in a universal consciousness or a spirit world or something like that. I think that’s wrong – I think you can maintain the epistemic and spiritual value of psychedelic experience without believing in those things. 

So I spend a big part of the book looking at the mechanisms of psychedelic therapy. How does it work? How does it in fact help people psychologically? I’m trying to respond to the question Michael Pollan posed in an article in the New Yorker: “Is psychedelic therapy simply foisting a comforting delusion on the sick and dying?”. I call this the “Comforting Delusion Objection” to psychedelic therapy.

Now, I don’t think Pollan is using the term “delusion” in a clinical sense; he’s just using it to mean a deeply held false belief about reality. But the word ‘comforting’ implies a mechanistic claim: that these false beliefs are doing the bulk of the therapeutic work. To evaluate that, I go pretty deeply into the evidence about what actually is helping people in psychedelic therapy.

The conclusion I draw is that it’s not about beliefs in non-naturalistic realities. It’s not beliefs in a cosmic consciousness or a great beyond that are the main therapeutic agent. Instead, I argue it’s profound experiences in which people realise that their sense of self and their self-narratives are contingent and changeable, and discover new and healthier ways of seeing themselves and their lives, and relating to their experience. I argue that this is the main therapeutic process, common to the treatment of all these different psychiatric conditions.

Metaphysical belief changes might also contribute to the therapeutic outcomes and clinical benefits in some cases. But the evidence, as I analyze it, shows that those kinds of belief changes are not universal, and they’re not the main thing driving therapeutic change.

Having developed this picture of how psychedelic therapy works, I use that as a basis to argue that it has various types of epistemic benefits. I talk about different kinds of knowledge and insights that people gain in these experiences. And I talk about the idea of naturalistic spirituality – that there can be experiences that we can legitimately call spiritual, but that don’t actually involve belief in anything beyond the natural world. 

“There can be experiences that we can legitimately call spiritual, but that don’t actually involve belief in anything beyond the natural world.”

Jessica Lawson: I wonder what people’s responses have been? For non-spiritual or non-religious people who are trying to make meaning from a psychedelic experience, I would imagine it’s really helpful to frame it in a secular way, and focus on the benefits of seeing the self differently, as well as caring for the environment and humanity more… What kind of feedback have you had? 

Chris Letheby: In general, really positive. I’ve been really pleased with the response. There are a lot of people who need and value a framework that allows them to make sense of these experiences in a way that is secular, is naturalistic, but simultaneously really tries to do justice to the richness and the depth and the value of the experience and its epistemic and spiritual dimensions. And of course there are people who are more attracted to non-naturalist metaphysics and who think that my framework doesn’t do justice to the psychedelic experience, and that’s fair enough, there’s a lot to debate. There are obviously enough people out there who think as I do – that these experiences have epistemic and spiritual implications and benefits, even though they don’t have radical metaphysical implications – that it’s really valuable for these people to have a philosophical framework for making sense of their experiences.

Chris Letheby
Philosopher Chris Letheby.

I’ve had a bit to do with researchers at both Johns Hopkins University and Imperial College London and I’ve found an intellectual synergy between what I’ve been trying to do philosophically and the work of both groups. One thing that I love about the research program at Johns Hopkins is that it has always been so focused on the spiritual and the mystical dimensions, and the non-medical uses of psychedelics. That’s the stuff that interests me the most. But then the intellectual bent of the Imperial program with Robin Carhart-Harris is very explicitly trying to demystify the psychedelic experience. They don’t buy into extravagant metaphysics, but they want to do justice to the richness and the value of the experience in a way that is scientifically grounded. They are advancing ideas about things like connectedness and acceptance. If the central features aren’t learning about another metaphysical reality or meeting God or transcending the material world, then what are they? 

Jessica Lawson: You’ve lectured on the philosophy of psychiatry and you’ve written some papers on the applications of psychedelic-assisted therapy for body dysmorphic disorder. Do you have any plans to work in clinical settings or design frameworks to assist in clinical research? 

Chris Letheby: I have thought about this – if there is a way we can try to make philosophical framings available to people undergoing these experiences in clinical settings. Philosophy is a controversial field and obviously I think my framework is the right one, but everyone thinks their framework is the right one. So we shouldn’t just give people one framework – what would be good is to make people aware and make available information on the basics of several different philosophical frameworks for making sense of their experiences. Peter Sjöstedt-Hughes has been developing ideas along these lines, I believe.

It would be a good idea to equip people with some basic critical thinking tools. The Finnish philosopher Juuso Kähönen wrote a great Master’s thesis on the psychedelic experience and moral enhancement – how psychedelics can enhance moral perception. But he also considers this concern that I talk about a lot: that psychedelic experiences might give people false beliefs or impair their rational thinking. He thinks we should try to equip people in advance of having these experiences. And of course, the idea is not that people should be sitting there during the psychedelic experience thinking critically “is it real or not?” The way to have the experience is to be open and let it be what it is. But some kind of “epistemological psychoeducation”, as Kähönen calls it, or basic critical thinking skills for when they come out the other side, is a really good idea.

“psychedelic experiences might give people false beliefs or impair their rational thinking”

I have been involved in some clinical research, most notably the trial of psilocybin-assisted therapy for generalised anxiety disorder at Monash University. I was involved with Paul Liknaitzky and Vince Polito in the design of that, selecting psychometric measures and developing hypotheses to test.

As you mentioned, I also co-wrote a paper called ‘Psychedelic therapy for body dysmorphic disorder’ (BDD) with clinical psychologist Shevaugn Johnson. Psychedelic therapy, in our view, looks like a really promising treatment for BDD. Now Shevaugn is the expert on BDD, but her ideas about using psychedelics in that condition dovetailed with a theoretical framework I’ve developed in collaboration with my colleague Philip Gerrans, a philosopher at University of Adelaide. This is the ‘self-unbinding theory’ of psychedelic therapy – the idea that psychedelic therapy is all about disintegrating and revising mental models of the self – and this provides a strong theoretical basis for thinking that psychedelics might help in BDD. In BDD, mental models of the self become dysfunctional or unhealthy in some way. Physical or bodily models, in particular, are somehow distorted and cause harm. And so if you could allow the patient to discover new mental models of the physical and bodily self, that would seem to be exactly what’s needed, and there are some case reports suggesting that this kind of thing can happen. 

“This is the ‘self-unbinding theory’ of psychedelic therapy – the idea that psychedelic therapy is all about disintegrating and revising mental models of the self”

I also worked with Chris Timmermann and others at Imperial College London to develop a scale for measuring metaphysical beliefs, to see if psychedelic experiences really do change people’s beliefs about the mind/body problem and the nature of reality. They administered that questionnaire in a survey study and in a clinical trial using psilocybin for depression. 

Finally, I have a collaboration in progress with Matt Johnson and others at Johns Hopkins, developing hypotheses and questionnaires to be applied in clinical research. We’re trying to narrow down questions about the main therapeutic mechanisms and how they overlap. Peter Hendricks says it’s all about the experience of awe. Robin Carhart-Harris and Karl Friston say it’s about relaxing and revising beliefs. Others think it’s all about metaphysical beliefs, or connectedness and acceptance. I say it’s all about changing self-models – insights into the malleability of the self and the constructed nature of self-narratives and so on. These ideas overlap, but they’re not exactly the same. 

“Peter Hendricks says it’s all about the experience of awe. Robin Carhart-Harris and Karl Friston say it’s about relaxing and revising beliefs. Others think it’s all about metaphysical beliefs, or connectedness and acceptance. I say it’s all about changing self-models”

Even if you accept that the therapeutic mechanism is a psychological process, and not just an unconscious, purely neurobiological thing as some people suggest, there are still these questions about what psychological process, exactly, is doing the work. So that’s been the focus of some of my recent collaborative work: trying to empirically delineate the therapeutic mechanisms in a more fine-grained way.   

Jessica Lawson: You’re presenting at Entheogenesis Australis’ Garden States conference in December. What do you think are the common goals between your work and the conference mission? And what can people expect from your presentation? 

Chris Letheby: There are a lot of common goals – primarily to better understand the psychedelic experience in all its rich, confusing, confounding glory – and to get the most knowledge and the least delusion, the most benefit and the least harm out of it, for everyone who’s affected by it. For my presentation I’ll give an overview of a paper that I co-authored with Jaipreet Mattu from the University of Western Ontario, outlining four main themes that we think have emerged in philosophical discussion of psychedelics in the last decade. First, there are issues in the philosophy of mind: what can psychedelics tell us about the self and self-consciousness? Second, issues in epistemology – do people gain knowledge from psychedelic experiences? If so, what kind? Third, what ethical issues are raised by the use of psychedelics? Can psychedelics themselves function as moral enhancement agents? And then, finally, issues to do with religion and spirituality: can psychedelics show that there are forms of religious practice or spiritual practice that are compatible with a naturalistic worldview?

“Can psychedelics themselves function as moral enhancement agents?”

Jessica Lawson: Sounds interesting. I’m sure the philosophy nerds will love it as well as everybody else at the conference. Thanks so much Chris. It’s been a real pleasure talking to you. 

Chris Letheby: My pleasure.

Interview by Jessica Lawson and copy edited by Anita Spooner

Find the Philosophy of Psychedelics By Chris Letheby

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