Recent clinical trials show that psychedelics such as LSD and psilocybin can be given safely in controlled conditions, and can cause lasting psychological benefits with one or two administrations. Supervised psychedelic sessions can reduce symptoms of anxiety, depression, and addiction, and improve well-being in healthy volunteers, for months or even years. But these benefits seem to be mediated by "mystical" experiences of cosmic consciousness, which prompts a philosophical concern: do psychedelics cause psychological benefits by inducing false or implausible beliefs about (...) the metaphysical nature of reality? This book is the first scholarly monograph in English devoted to the philosophical analysis of psychedelic drugs. Its central focus is the apparent conflict between the growing use of psychedelics in psychiatry and the philosophical worldview of naturalism. Within the book, Letheby integrates empirical evidence and philosophical considerations in the service of a simple conclusion: this "Comforting Delusion Objection" to psychedelic therapy fails. While exotic metaphysical ideas do sometimes come up, they are not, on closer inspection, the central driver of change in psychedelic therapy. Psychedelics lead to lasting benefits by altering the sense of self, and changing how people relate to their own minds and lives-not by changing their beliefs about the ultimate nature of reality. The upshot is that a traditional conception of psychedelics as agents of insight and spirituality can be reconciled with naturalism (the philosophical position that the natural world is all there is). Controlled psychedelic use can lead to genuine forms of knowledge gain and spiritual growth-even if no Cosmic Consciousness or transcendent divine Reality exists. Philosophy of Psychedelics is an indispensable guide to the literature for researchers already engaged in the field of psychedelic psychiatry, and for researchers-especially philosophers-who want to become acquainted with this increasingly topical field. (shrink)

Users of psychedelic drugs often report that their sense of being a self or ‘I’ distinct from the rest of the world has diminished or altogether dissolved. Neuroscientific study of such ‘ego dissolution’ experiences offers a window onto the nature of self-awareness. We argue that ego dissolution is best explained by an account that explains self-awareness as resulting from the integrated functioning of hierarchical predictive models which posit the existence of a stable and unchanging entity to which representations are bound. (...) Combining recent work on the ‘integrative self' and the phenomenon of self-binding with predictive processing principles yields an explanation of ego dissolution according to which self-representation is a useful Cartesian fiction: an ultimately false representation of a simple and enduring substance to which attributes are bound which serves to integrate and unify cognitive processing across levels and domains. The self-model is not a mere narrative posit, as some have suggested; it has a more robust and ubiquitous cognitive function than that. But this does not mean, as others have claimed, that the self-model has the right attributes to qualify as a self. It performs some of the right kinds of functions, but it is not the right kind of entity. Ego dissolution experiences reveal that the self-model plays an important binding function in cognitive processing, but the self does not exist. (shrink)

The urgent need for solutions to critical environmental challenges is well attested, but often environmental problems are understood as fundamentally collective action problems. However, to solve to these problems, there is also a need to change individual behavior. Hence, there is a pressing need to inculcate in individuals the environmental virtues — virtues of character that relate to our environmental place in the world. We propose a way of meeting this need, by the judicious, safe, and controlled administration of “classic” (...) psychedelic drugs as a way to catalyze the development of environmental virtues – a form of moral bio-enhancement. Recent evidence shows that psychedelics can be given safely in controlled environments, and can induce vivid experiences of unity and connectedness. These experiences, in turn, can durably increase feelings of nature-relatedness and pro-environmental behaviors. Therefore, we argue that responsible psychedelic use can reliably catalyze the development of a key environmental virtue known as living in place. This is a “master environmental virtue” that subsumes the qualities of respect for nature, proper humility, and aesthetic wonder and awe. Our account advances the environmental virtues debate by introducing a relevant practical proposal, and advances the psychedelic moral enhancement debate by providing a much-needed conceptual framework. (shrink)

Can there be phenomenal consciousness without self-consciousness? Strong intuitions and prominent theories of consciousness say “no”: experience requires minimal self-awareness, or “subjectivity”. This “subjectivity principle” faces apparent counterexamples in the form of anomalous mental states claimed to lack self-consciousness entirely, such as “inserted thoughts” in schizophrenia and certain mental states in depersonalization disorder. However, Billon & Kriegel have defended SP by arguing that while some of these mental states may be totally selfless, those states are not phenomenally conscious and thus (...) do not constitute genuine counterexamples to SP. I argue that this defence cannot work in relation to certain experiences of ego dissolution induced by potent fast-acting serotonergic psychedelics. These mental states jointly instantiate the two features whose co-instantiation by a single mental state SP prohibits: phenomenal consciousness and total lack of self-consciousness. One possible objection is that these mental states may lack “me-ness” and “mineness” but cannot lack “for-me-ness”, a special inner awareness of mental states by the self. In response I propose a dilemma. For-me-ness can be defined either as containing a genuinely experiential component or as not. On the first horn, for-me-ness is clearly absent from my counterexamples. On the second horn, for-me-ness has been defined in a way that conflicts with the claims and methods of its proponents, and the claim that phenomenally conscious mental states can totally lack self-consciousness has been conceded. I conclude with some reflections on the intuitive plausibility of SP in light of evidence from altered states. (shrink)

Psychedelic ingestion and meditative practice are both ancient methods for altering consciousness that became widely known in Western society in the second half of the 20th century. Do the similarities begin and end there, or do these methods – as many have claimed over the years – share some deeper common elements? In this chapter I take a neurophilosophical approach to this question and argue that there are, indeed, deeper commonalities. Recent empirical studies show that psychedelics and meditation modulate overlapping (...) brain networks involved in the sense of self, salience, and attention; moreover, psychedelics can occasion lasting increases in “mindfulness-related capacities” for taking a non-reactive stance on one’s inner experience (e.g. Sampedro et al. 2017). The self-binding theory of psychedelic ego dissolution (Letheby and Gerrans 2017) offers a plausible explanation of these findings: by disrupting self-related beliefs implemented in high-level cortical networks, both psychedelics and meditation can “unbind” mental contents from one’s self-model, moving these contents along the continuum from phenomenal transparency to opacity (cf. Metzinger 2003). In other words, both psychedelics and meditation can expose and weaken our foundational beliefs about our own identity, allowing us to disidentify with these beliefs and see them as “just thoughts”. There are connections between these ideas and recent arguments suggesting that psychedelic use may have epistemic benefits consistent with philosophical naturalism (Letheby 2015, 2016, 2019). I conclude with a proposal: these connections may help in thinking about the putative epistemic benefits of meditation practice from a naturalistic perspective. (shrink)

One recent development in epistemology, the philosophical study of knowledge, is the notion of ‘epistemic innocence’ introduced by Bortolotti and colleagues. This concept expresses the idea that certain suboptimal cognitive processes may nonetheless have epistemic (knowledge-related) benefits. The idea that delusion or confabulation may have psychological benefits is familiar enough. What is novel and interesting is the idea that such conditions may also yield significant and otherwise unavailable epistemic benefits. I apply the notion of epistemic innocence to research on the (...) transformative potential of psychedelic drugs. The popular epithet ‘hallucinogen’ exemplifies a view of these substances as fundamentally epistemically detrimental. I argue that the picture is more complicated and that some psychedelic states can be epistemically innocent. This conclusion is highly relevant to policy debates about psychedelic therapy. Moreover, analysing the case of psychedelics can shed further light on the concept of epistemic innocence itself. (shrink)

Much of my book Philosophy of Psychedelics is devoted to elaborating and defending two basic claims: that psychedelic therapy works mainly by changing mental representations of the self, and that it has many epistemic benefits consistent with a naturalistic worldview. The commentaries in this symposium generally focus on one or the other of these claims. On the mechanistic front, the commentaries by Hoffman and by Martin and Sterzer seek to supplement my account by drawing attention to factors it does not (...) emphasize. In this reply I agree with most of their claims, but propose some important qualifications. Meanwhile, the commentaries by Lyon and Farrenikova and by Colombo challenge some core commitments of my account. I agree with many of their claims, but defend some of these core commitments. On the epistemological front, Bortolotti and Murphy-Hollies endorse the overall shape of my account and make some productive connections to ideas concerning agency-first epistemology and self know-how. Caporuscio brings into play the idea of self-shaping, which connects to self know-how, but argues against certain core claims of my account. I endorse many of these claims about agency-first, self know-how, and self-shaping, but propose some important qualifications. Finally, Fink agrees that psychedelic experiences can have some epistemic benefits, but argues that these do not pertain to epistemic justification, and that the main benefit is increased understanding. I am sympathetic to Fink’s proposal about understanding, but criticize some of his arguments for the thesis of Psychedelic Justification Impossibilism. (shrink)

Several authors have recently suggested that classic psychedelics might be safe and effective agents of moral enhancement. This raises the question: can we learn anything interesting about the nature of moral experience from a close examination of transformative psychedelic experiences? The interdisciplinary enterprise of philosophical psychopathology attempts to learn about the structure and function of the “ordinary” mind by studying the radically altered mind. By analogy, in this chapter we argue that we can gain knowledge about the everyday moral life (...) by studying extraordinary experiences of altered moral cognition and experience. We focus on a specific class of cases: experiences of forgiveness induced by psychedelics. We argue that close attention to such experiences reveals the importance of thought/emotion coherence and dissonance in the moral life and vindicates some heterodox ideas about moral phenomenology and psychology. (shrink)

In this précis I summarise the main ideas of my book Philosophy of Psychedelics. The book discusses philosophical issues arising from the therapeutic use of “classic” psychedelic drugs such as psilocybin and LSD. The book is organised around what I call the Comforting Delusion Objection to psychedelic therapy: the concern that this novel and promising treatment relies essentially on the induction of non-naturalistic metaphysical beliefs, rendering it epistemically objectionable. I begin the précis by summarizing material from chapters two and three (...) of the book, which review evidence for the therapeutic efficacy of psychedelics, and the facts about their clinical use that prompt the Comforting Delusion Objection. I then summarize materials from chapters four and five of the book, which argue that psychedelic therapy works neither by experience-independent processes of neuroplasticity, nor by inducing non-naturalistic metaphysical ideations, but by altering mental representations of the self. Next, I summarise the specific, speculative account of how this might work that is developed in chapters six and seven of the book. This account is based on the predictive processing theory of brain function and the self-binding theory of self-representation. Chapters eight and nine of the book argue, on the basis of this account, that psychedelic therapy can have significant epistemic and spiritual benefits that are compatible with a naturalistic worldview. I summarize this material, and then, finally, the overall conclusions about psychedelic therapy drawn in the tenth and final chapter of the book. (shrink)

In this opinion piece we propose the investigation of psychedelic-assisted psychotherapy for the treatment of body dysmorphic disorder (BDD). BDD is a psychiatric disorder characterised by appearance-based preoccupations and accompanying compulsions. While safe and effective treatments for BDD exist, non-response and relapse rates remain high. Therefore, there is a need to investigate promising new treatment options for this highly debilitating condition. Preliminary evidence suggests safety, feasibility, and potential efficacy of psychedelic treatments in disorders that share similar psychopathological mechanisms with BDD. (...) Drawing on this evidence, as well as on relevant qualitative reports and theoretical proposals, we argue that it would be worthwhile to conduct a phase 2a study aimed at assessing the safety and feasibility of psychedelic-assisted psychotherapy in BDD. We also offer some suggestions for how future research ought to proceed. (shrink)

Recent scientific research into the therapeutic potential and mechanisms of psychedelic drugs raises intriguing and hitherto largely unexplored philosophical questions. A brief overview of the relevant science is given before addressing these questions. It is argued that psychedelic transformation is a distinctive psycho- pharmacological intervention because its mechanism of action ineliminably involves conscious mental representations, and thus is more transparent to the subject than the mechanisms of other drug therapies. This argument connects with issues in the philosophy of (cognitive) scientific (...) explanation. It is also argued that transformative psychedelic experiences may well confer three distinct kinds of epistemic benefits: knowledge by acquaintance of the subject's psychological potential, knowledge by acquaintance of the meta-physical nature of the (sense of) self, and revitalized capacities for the acquisition of modal knowledge. Non-naturalistic metaphysical and epistemological claims abound in psychedelic circles; thus, it is important to realize that psychedelics may yield naturalistically acceptable epistemic benefits. (shrink)

Recent scientific research suggests that altered states of consciousness induced by classic psychedelic drugs can cause durable psychological benefits in both healthy and patient populations. The phenomenon of ‘psychedelic transformation’ has many philosophically provocative aspects, not least of which is the claim commonly made by psychedelic subjects that their transformation is centrally due to some kind of learning or knowledge gain. Can psychedelic experiences really be a source of knowledge? From the vantage point of philosophical materialism or naturalism, a negative (...) answer is tempting because psychedelic subjects often claim drug-facilitated knowledge of non-natural, transcendent realities. This fact, combined with common conceptions of these drugs as ‘hallucinogenic’ or ‘psychotomimetic’, invites the conclusion that claims of epistemic benefit from psychedelic experience are uniformly false. However, several recent proposals have been made in the literature about naturalistically acceptable epistemic benefits that might arise from psychedelic use. In this chapter I review these proposals, classifying them in accordance with standard epistemological categories, and discuss the arguments for and against them. I also offer some suggestions for future research. (shrink)

Can the use of psychedelic drugs induce lasting changes in metaphysical beliefs? While it is popularly believed that they can, this question has never been formally tested. Here we exploited a large sample derived from prospective online surveying to determine whether and how beliefs concerning the nature of reality, consciousness, and free‑will, change after psychedelic use. Results revealed significant shifts away from ‘physicalist’ or ‘materialist’ views, and towards panpsychism and fatalism, post use. With the exception of fatalism, these changes endured (...) for at least 6 months, and were positively correlated with the extent of past psychedelic‑use and improved mental‑health outcomes. Path modelling suggested that the belief‑shifts were moderated by impressionability at baseline and mediated by perceived emotional synchrony with others during the psychedelic experience. The observed belief‑shifts post‑psychedelic‑use were consolidated by data from an independent controlled clinical trial. Together, these findings imply that psychedelic‑use may causally influence metaphysical beliefs—shifting them away from ‘hard materialism’. We discuss whether these apparent effects are contextually independent. (shrink)

A pressing philosophical problem is how to respond to the existential, anxiety and disenchantment resulting from a naturalistic worldview that eschews transcendent foundations for meaning and value. This problem is becoming more urgent as the popularization of neuroscientific findings renders a disenchanted conception of human beings ever more vivid, compelling, and widespread. I argue that the study of transformative experiences occasioned by classic psychedelic drugs such as lysergic acid diethylamide and psilocybin may reveal the nature of a viable practical solution (...) to this problem. Despite the apparent centrality of nonnaturalistic metaphysical apprehensions to psychedelic transformation, findings from psychedelic research suggest that key elements of psychedelic or “entheogenic” spirituality are consistent with naturalism. These include disruption to neurocognitive mechanisms underpinning the sense of self, and consequent experiences of self-transcendence and of the decoupling of attention from personal concerns. This liberation of attention can result in the availability of broader perspectives and the development of wonder and appreciation for life. (shrink)

“Classic”, serotonergic psychedelic drugs such as LSD and psilocybin are the objects of renewed attention in science and psychiatry. A recent spate of research has produced evidence that psychedelics might be safe and effective adjuncts to the treatment of mood and addictive disorders, agents of positive psychological change in healthy subjects, and valuable tools for studying the neural mechanisms of perception and cognition. This chapter surveys three philosophical debates that have arisen in response to this “renaissance” of psychedelic research. The (...) first concerns the mechanisms of psychedelic-assisted psychotherapy (“psychedelic therapy”): How, exactly, does psychedelic administration in controlled conditions cause lasting psychological benefits? The second concerns the implications of psychedelic research for the philosophy of mind: Does psychedelic evidence show that there can be conscious mental states lacking all forms of self-consciousness? The third concerns the epistemic status of the psychedelic state: Is it possible that certain kinds of knowledge, or other epistemic benefits, could be gained by undergoing a psychedelic experience? (shrink)

Serotonergic (or “classic”) psychedelics have struck many researchers as raising significant philosophical questions that, until recently, were largely unexplored by academic philosophers. This paper provides an overview of four emerging lines of research at the intersection of academic philosophy and psychedelic science that have gained considerable traction in the last decade: selfless consciousness, psychedelic epistemology, psychedelic ethics, and spiritual/religious naturalism. In this paper, we highlight philosophical questions concerning (i) psychedelics, self-consciousness, and phenomenal consciousness, (ii) the epistemic profile of the psychedelic (...) experience; (iii) ethical concerns about the appropriate use of psychedelics; and (iv) whether spiritual or religious dimensions of psychedelic use are compatible with a naturalistic worldview. (shrink)

An emerging body of research suggests that psychedelic experiences can change users’ religious or metaphysical beliefs. Here I explore issues concerning psychedelic-induced belief change via a critique of some recent arguments by Wayne Glausser. Two scientific studies seem to show that psychedelic experiences can convert atheists to belief in God, but Glausser holds that academic and popular discussions of these studies are misleading. I offer a different analysis of the relevant findings, attempting to preserve the insights of Glausser’s critique while (...) setting the record straight on some important points. For one thing, the studies provide stronger evidence for atheist deconversion than Glausser allows. For another, Glausser’s arguments against the “Metaphysical Belief Theory” of psychedelic therapy involve scientifically dubious claims and inferences. Finally, in evaluating this theory, we ought to focus on its strongest version, which posits belief shifts from metaphysical naturalism to non-naturalism, rather than from atheism to classical monotheism. (shrink)

Resumen. El objetivo de este ensayo consiste en mostrar que tipo de conocimiento de puede adquirir en las experiencias psicodélicas, pero tomando como marco de referencia una posición naturalista. En este texto se analizan tres formas en las que esto es posible: 1) la introspección psicodinámica o el saber qué, 2) el saber cómo, que se vincula con el aprendizaje de alguna habilidad concreta y 3) el conocimiento por familiaridad. No son todas las que son posibles, pero si son suficientes (...) para mostrar algunos de los temas que ha de abordar la epistemología psicodélica. -/- Abstract: The aim of this paper is to show what kind of knowledge can be acquired in psychedelic experiences but taking as a frame of reference a naturalistic position. In this text three ways in which this is possible are analyzed: 1) psychodynamic introspection or knowing what, 2) knowing how, which is linked to the learning of some concrete skill, and 3) knowledge by familiarity. These are not all that are possible, but they are sufficient to show some of the issues to be addressed by psychedelic epistemology. (shrink)

Fred Adams : 619–628, 2010) criticizes the theory of embodied cognition which holds that conceptual and linguistic thought is grounded in the brain’s perceptual and sensorimotor systems. Among other things, Adams claims that: EC is potentially committed to an implausible criterion of sentence meaningfulness; EC lacks claimed advantages over rival accounts of conceptual thought; relevant experimental data do not show constitutive, but only causal, involvement of perception in conception; and EC cannot account for the comprehension of abstract concepts. I respond (...) to Adams that: EC is not committed to an implausible criterion of meaningfulness, though it may be committed to holding that comprehension admits of degrees; EC does have its claimed advantages over rival views; the data do make a strong case for constitutive involvement and a broad and comprehensive EC approach probably can account for the comprehension of abstract concepts. (shrink)