Dr. Chris Letheby is a superstar philosopher at UWA. He is not just a great person to interact with but he clearly has one very intriguing research topic: the philosophy of psychedelics. Below is the, mildly edited, transcript from an interview with Chris. The interview was conducted by our very own Sagacity Magazine editor, Lucia C. Neco.
4a: Does the fact that psychedelic use, in your words, ‘promotes a more open, less biased, and potentially more accurate mode of introspection’ help to explain why psychedelic experiences can be so positive for someone? Is there something intrinsic about those experiences that makes them positive for the people who have them? Because I can think of examples of people who haven’t had good psychedelic experiences.
Yeah, you're absolutely right. It's not the case that all psychedelic experiences are pleasant or beneficial. The very capacity that allows these substances to give some people the best experience of their lives also allows them to give some people the worst experience of their lives.
That said, we do know a lot about how to maximise the probability of a beneficial experience, which isn't the same thing as a uniformly pleasant experience. This is worth mentioning, because people are not always aware that even the experiences that do lead to transformative outcomes and personality change and lasting reduction in psychiatric symptoms very often have parts of them that are extremely difficult or unpleasant for the person undergoing it. Now, the evidence is that psychedelics are physically extremely safe—there's no physiological dependence liability when we're talking about the serotonergic classic psychedelics, such as LSD and psilocybin. Generally speaking, unless people have a condition to do with the heart or blood pressure, [psychedelics are] physically extremely safe.
The risks are psychological and there are certainly cases of lasting psychosis being precipitated by a psychedelic experience. The consensus at the moment seems to be that this only really happens when there's some predisposition, or maybe in some rare cases where an extremely large dose is taken under extremely unsuitable circumstances.
In modern clinical research, a lot of care is taken and basically anyone with a personal or immediate family history of any kind of psychotic illness—schizophrenia or psychotic depression or bipolar—is excluded because that's regarded as a risk factor.
4b: Okay, but why is [the experience] positive?
It's because self-representation is incredibly important to how we experience the world. This is something that is not always introspectively obvious, but there is a lot of evidence from neuroscience, from psychiatry, and from psychology that our mental representations of the self play a deep, extensive, and pervasive role in cognitive processing. We have all these different layers of self-representation ranging from what they call minimal or bodily self-representations, all the way to the narrative or autobiographical self-representations—the model that you have of the particular person you are, your particular character traits, your life history, your goals and plans for the future, your relationships, and so on.
The neurocognitive systems involved in generating and processing these representations of the self also play extremely important roles in regulating attention and the attribution of salience. So, as we're going through the world, certain things jump out at us, they grab our attention, they strike us as being important, worth thinking about and worth noticing, and other things simply recede into the background and strike us as boring, uninteresting, or we just don't even notice or give them a second's consideration. And this is all based largely on the self-model.
What we pay attention to is a function of who we think we are, what we think we need, and what we think our goals are. And so our representations of the self affect our lives and our experience of the world profoundly, and this is what psychedelics seem to do—it’s not the only thing they do, but one of the central things they do is they disrupt these self-modelling systems.
4c: So, these neural networks–the two that get talked about a lot–are the default mode network and the salience network, and psychedelics really seem to target these and disrupt their coherent functioning for better or worse, right?
Right. And so disintegration of the ordinary sense of self is also a hallmark of psychosis, and it's a hallmark of schizophrenia and various unpleasant, deleterious ways in which consciousness can be altered. And so this is the sort of thing psychedelics can do if you're careless or if you're unlucky—they can disrupt the ordinary sense of self, leading to extremely unpleasant, harmful, and dysphoric results. But in typical controlled clinical settings, what they seem to do is disrupt the sense of self in beneficial ways.
Just think about cases of psychedelic treatment for addiction, such as for substance use disorders. One problem that often happens in cases of addiction is that the person is unable to simulate an alternative sense of self – they’re unable to vividly imagine and relate to a sense of self as something other than an addict (a gambler, a drinker, a user, or whatever it might be). So, this particular self-image that is tied up with the addiction and the object of addiction becomes extremely rigid and deeply entrenched. Such a person may acknowledge verbally or intellectually that it is, in some sense, possible for them to stop the addiction – to have a different kind of life – but [this possibility is not thought of as] subjectively real: They can't emotionally connect with that possibility. So the realisation of it being possible to stop the addiction often doesn’t have any kind of motivational or behavioural effect.
So, what psychedelics seem able to do is disrupt that usual process. People can get stuck in a kind of feedback loop, right? For example, from day to day you may have a particular sense of who you are and what matters to you, which leads you to focus on certain things and ignore others. And it’s natural to then focus on things that confirm that existing picture of who you are, give you more and more evidence that you’re a particular kind of person and your life is a certain kind of life. So, you minimise prediction error by behaving in ways and paying attention in ways that are consistent with the picture of yourself that you already have. This is called ‘active inference’ in the cognitive science literature. ‘Active inference’ was first used in relation to predictive coding and predictive processing theories of cognition, [according to which] we tend to seek out evidence that's going to confirm our existing models of the world … and so the idea is that active inference is what we do in relation to ourselves as well. Active inference is not problematic, by and large, but when it goes wrong you can end up with an extremely maladaptive and rigid self-model. In short, it seems like what psychedelics can do is disintegrate that self-model, break it open, and then give you a chance to experience alternative kinds of self-modelling.
Suppose you have an addiction, and they give you the first chance you've had in years to experience to really experience, on a kind of embodied, somatic, affective, perceptual, gut level, a ‘me’ that is not an addict—a ‘me’ that is not in bondage to whatever this kind of pattern of behaviour is. The theory is that all this is basically lodged in the self-model. Then you can get these new models of self that might be more flexible, more beneficial, more positive—possibly, in some respects, more accurate—and then you also have this newfound degree of cognitive flexibility. So there's a window of opportunity for change: There's some kind of opportunity to actually consolidate this new representation of the self in what they call the ‘integration period’ after the experience.
So, if you're doing this deliberately for therapeutic or transformative purposes, then you have to try to consolidate the new sense of self; otherwise, the gravitational pull of the old, pathological, negative sense of self is just going to be too great. Sadly, that's what seems to happen in a lot of these trials. People do actually stay better for a period of a few months, but then—especially if they're still in a dysfunctional environment that has contributed to the genesis of whatever their condition is—they end up relapsing a lot of the time. So the going wisdom is that, to really make the change stick, you have to meet with the psychologist, or the psychiatrist, or the shaman, or whoever it is [who assisted you] multiple times after the experience and discuss what happened and the insights that came up. It's not like a magical solution. It's not a magic bullet.
Although there are cases where it does seem to be something like a magic bullet, and these are the cases that get people really excited and really impressed, and I think there are such cases; I just think they're relatively rare. I think most people who go in and take psychedelics in a controlled sort of therapeutic or transformative setting are not going to have this experience. Because some people use the model of inverse PTSD … they say, look, PTSD is a proof of concept that a single, discrete, overwhelming, emotionally intense experience can profoundly rewire cognitive processing. In some cases, this same sort of profound change in cognitive processing happens in psychedelic therapy, it is just that unlike the PTSD case, the experience is positively valence. I think for some people, this occurs. I think these tend to be the people who have the actual full-blown classical mystical experience, the cosmic consciousness type thing that William James and Walter Stace were talking about. In those cases, it sometimes seems as though the transformation just happens on its own. It's, perhaps, just a matter of the experience being so overwhelming and so positive that the person can't help revisiting it, and it just changes how they see the world permanently. But I think most cases are not like that.
In most cases, you get a kind of powerful glimpse of a different way you could be, and a different way you could relate to your own mind and to the world and to other people. You get a window of opportunity for change, a period of a couple of weeks to a couple of months, in which your cognitive processing is more flexible and you can intervene. And then what you have to do during that period of time is deliberately, in consultation with the therapist, try to consolidate these new ways of seeing yourself and new ways of seeing the world.
Thinking philosophically about those experiences also has to do with thinking about the nature of the self. Specifically, what the self is and what the psychedelic experience can teach us about it. There are separate questions that we need to distinguish. First, ‘what, if anything, can [psychedelic experiences] teach us about the self, metaphysically?’. Second, ‘what can they teach us about self-consciousness or self-awareness as a phenomenological/psychological phenomenon?’.
On the first count, the metaphysical, I've argued that the evidence from psychedelic neuroscience can actually contribute to an argument for anti-realism about the self—the view that there is no such thing, metaphysically, as the self. I'm very much following in the footsteps of a lot of other philosophers in having this view. The most recent is Thomas Metzinger, who has a large body of work drawing on evidence from altered states, psychiatric pathologies, and even, to an extent, psychedelics—writing on the latter back when very few in academic philosophy were doing so.
The argument Metzinger makes is basically that we represent the self as being something like a Cartesian ego, a persisting substance distinct from all our various physical, mental, and emotional states. We represent the self as an entity that ‘stands in’ those states, and processes, a single, simple, unified agent of the actions, the thinker of the thoughts that is strictly numerically identical across time. Under this view, the self you are, now, is the very same self you were when you were five years old.
So Metzinger draws on evidence from all these pathologies and altered states to argue that, while this is in fact the content of our mental representation of the self, there [isn’t] any such thing as a Cartesian ego. Metzinger’s argument has the same structure as J.L. Mackie’s arguments for moral error theory, wherein he says, first of all, that our ordinary moral thought and talk is committed to something like objective prescriptions—mind independent facts about what is to be done. So this is a semantic claim. Then, [for the moral error theorist], there's an ‘ontological claim’, [which is that] there aren't any such things as objective prescriptions. The Metzinger-style anti-realism about the self has the same two-part structure. It's got the psycho-semantic claim that we represent the self as something like a Cartesian ego, and then the ontological claim that there aren't any Cartesian egos.
I think psychedelic experience supports the first part, the semantic claim. Within psychedelic research and in psychedelic culture, you have these terms that go around, [such as] ‘ego dissolution’, ‘ego death’, and ‘ego disintegration’. While these turn out to be quite imprecise terms, there's a lot of work going on at the moment in science and philosophy to try to disambiguate them and get more precise about what these things are. That being said, I think a relatively small subset of people who take high-dose psychedelics actually have conscious experiences that completely lack any sense of self.
So there's this idea of the ‘argument from phenomenal contrast’, I think it's Suzanna Siegel originally who says, look, if you want to prove that ordinary experience contains a particular type of phenomenal feature, one way to do that is by contrasting it with the type of experience which seems to lack that feature and that's how you can establish that some controversial phenomenal feature actually does exist: by pointing to an apparent contrast between two experiences and saying that the best explanation is that one of these experiences has this feature and the other one doesn't. That's the approach in psychedelic research. When we look at psychedelic experiences of total ego dissolution and contrast them with ordinary waking consciousness, the best explanation for the difference between the two is that, even if it's introspectively extremely elusive in ordinary waking consciousness, there is this experience as of being something like a Cartesian ego, and that's what goes away in psychedelic ego dissolution.
So, the above helps to answer the semantic question. However, none of what has been said helps to answer the other question, that ontologically, the self doesn't exist. Although maybe it does help with that in a somewhat indirect way, because you might say that one of the properties that a Cartesian ego should have is that it's something that we are directly acquainted with in experience, something which you never don’t experience. If the self is something like a subject of experience, that is necessarily experientially present in every experience, then yes, psychedelic ego dissolution helps to show that, ontologically, there is no such thing. Of course, the alternative explanation is that it makes people very bad at describing their experiences. So, maybe psychedelic experiences can contribute somewhat to answering the ontological question, but I think its main contribution is to the semantic question: giving us a window into what the ordinary sense of self actually is and what the content of the ordinary self-representation is, by giving us a contrast case in which it's absent.
5a: On that point about how people received your work: you said that there wasn’t a lot of philosophical discussion about psychedelics. More recently there's a lot more, correct?
In fact, next year will be the fourth year in a row that a major philosophy book on psychedelics is coming out. There was my monograph in 2021, then last year there was an edited collection from Bloomsbury, Philosophy and Psychedelics, edited by Christine Hauskeller and Peter Sjöstedt-Hughes. Then, a few weeks ago Aidan Lyon’s monograph Psychedelic Experience came out with OUP, and then next year my collection, co-edited with Phil Gerrans, Philosophical Perspectives on Psychedelic Psychiatry, will be out from OUP [now published here].
I certainly have been pleased by how well received philosophy of psychedelics has been by philosophers, but what I've been even more pleased by is how well received it's been by scientists and clinicians. I think it makes perfect sense because psychedelic research is a domain in which philosophical questions arise, obviously and inexorably. Still, I have just been incredibly heartened by how interested psychedelic neuroscientists, therapists, and psychologists are in the work and how open to collaboration, and open to incorporating philosophical insights into their own work. Yeah, it's been really nice.
5b: That's good. So you don't have anyone saying things like ‘you shouldn't be talking about psychedelics’?
Not really, no. I mean occasionally, very occasionally, people will point out that psychedelics are still illegal and so we shouldn’t be doing this research. Fortunately, most philosophers and most psychedelic researchers seem to realise that psychedelics being illegal doesn't constitute a compelling objection to any of this research. Though, I should issue my normal disclaimer that I am not advocating illegal acts and I'm not recommending psychedelic use; what I am trying to do is conduct a philosophical analysis of what actually is going on in these activities.
Psychedelics are completely illegal, with one exception: a few months ago, the TGA, the Australian Therapeutic Goods Administration, approved the use of psilocybin for treatment-resistant depression. It's still very highly regulated. I think what they've done is basically move psilocybin from schedule nine down to eight. So, if a psychiatrist wants to prescribe psilocybin, they need to get an ethics board approval. It's all very highly regulated and controlled. Outside of that [context], and outside of specific research studies, psychedelic use is still completely illegal in Australia.
I've always made the scope and the intent of my work clear, and I've never had any objections on grounds of illegality. I've certainly encountered, very occasionally, people who are completely closed to the idea that psychedelics could be beneficial. Usually I think that's because they've known someone personally who was very seriously harmed by psychedelics and then they're unable to get past that experience, which is understandable. For example, David Nutt, the British neuropsychopharmacologist, infamously compared the risks of taking ecstasy to horse riding, arguing that we permit many dangerous recreational activities, and he got sacked from his government position for it. The basic point about the risks of certain dangerous behaviours has been made for decades now. You had people like Alan Watts, back in the 1950s and 60s, making the point that there are lots of things that are extremely dangerous that we think are worth permitting on the basis that they can also have extreme benefits, like knives, rock climbing, and any extreme sport. Most people who know someone who's been seriously harmed or even who has died participating in some extreme sports are not lobbying for these things to be banned. But with psychedelics, personal proximity to harm often makes people resistant to the research.
You get other kinds of reactions as well. Some people are sceptical about the therapeutic and transformative potential of psychedelics, and that's a completely legitimate position to take. There are lots of methodological difficulties in trying to show that psychedelics really do have therapeutic and transformative potential because it's very hard to double-blind effectively, so a certain amount of scepticism there is legitimate. There's also the phenomenon where new therapies tend to get inflated initial results, which become less dramatic over time.
So there are all kinds of positions that people might legitimately have in response to psychedelic research. That kind of constructive, scholarly, and intellectual resistance has been the bulk of what I’ve encountered, rather than censorious resistance that says this isn't a topic you should even talk about.
6: If someone wants to start reading about philosophy of psychedelics, where should they start?
There are three good places to start. One is my book, Philosophy of Psychedelics. If you're into neurophilosophy and the philosophy of cognitive science, you probably want to start there. If you're into something a bit more continentally-flavoured [i.e., traditionally associated with continental philosophy], you should start with the collection from Bloomsbury, Philosophy and Psychedelics: Frameworks for Exceptional Experience. And if you want something that's a bit more like classical analytic philosophy, you could try Aidan Lyon’s new monograph Psychedelic Experience. Generally speaking, those are the broad orientations of the three books out so far.
I will say briefly that there are a lot of stones unturned in this area. There are a lot of really fascinating philosophical questions about psychedelics and about psychedelic research that nobody has really tried to tackle yet in a systematic philosophical way.
In the philosophy of mind and philosophical psychology, most of the emphasis so far has been on [points related to] self-awareness, but there's a lot more to psychedelic experience than changes to the self. There are interesting questions about the perceptual and the affective phenomena that arise, and interesting questions about large-scale cognitive architecture.
For instance, there are psychoanalytic explanations of psychedelic experience, and people talk about psychedelics as revealing the unconscious in some kind of psychoanalytic sense. But of course, a lot of people are sceptical that there is any such thing. So there are really interesting questions to be asked, [like] ‘does psychedelic experience give us evidence for some of the classical posits of psychoanalytic theory, like the unconscious?’
There are also really interesting questions in the philosophy of psychiatry, [like] ‘can we actually learn something about how our diagnostic categories should be reformed by looking at the way psychedelic therapy seems to work across different diagnoses?’ On the face of it, [psychedelic treatments] seem to address anxiety disorders, depression, and various addictive disorders in fundamentally the same way.
This raises interesting questions about what implications that might have, even, for example, in treating all those disorders as just one thing. There are these newer dimensional approaches to psychopathology which don't really look at psychiatric disorders as distinct nosological entities, but characterise them in terms of quantifiable or describable alterations or disruptions to a certain limited set of core dimensions of psychological functioning. Some people have suggested that psychedelic therapy might give some support to that approach, showing that [psychiatric disorders] might be better explained in terms of a dimensional approach, [rather] than a classical DSM-type approach.
So there are those sorts of questions, and there are loads of ethical questions I haven't talked about. There's lots to be done. Thank you.
Thank you!