The Return of the Philosophy of Psychedelics (And Why It Matters)

The ‘psychedelic renaissance’ is typically framed in terms of the resurgence of scientific research into the effects of psychedelics, covering aspects like neuroscience, psychology, psychotherapy, and mental health. However, in recent years, we’ve also seen increasing interest in the psychedelic experience from a philosophical perspective. 

The philosophy of psychedelics has a rich history. Yet there has long been a dearth of interest from academic philosophers in psychedelics, perhaps partly out of stigma (taking an interest in the subject could be seen as confirming the trope of philosophers being wacky and drug-addled) and partly out of unappreciation (not recognising just how many subdisciplines of philosophy tie into the psychedelic experience and/or failing to appreciate how fruitful it can be to explore these connections). 

I would like to delve into the return of the philosophy of psychedelics and why this is a trend that should be celebrated and encouraged.

One can speculate just how far back in time the link between psychedelics and philosophy extends, which can include the influence of psychedelic experience on philosophical thought. Perhaps the ancient Greek philosophers who attended the Eleusinian Mysteries – the secret initiation rituals of the mystery school of Eleusis (near Athens), a cult of the goddesses Demeter and Persephone – found inspiration for their ideas after imbibing kykeon, a psychoactive and sacred drink consumed at the ceremony following a fast. Well-known initiates included Plato, Socrates, Sophocles, Cicero, Plutarch, Hadrian, and Marcus Aurelius.

In their book The Road to Eleusis: Unveiling the Secret of the Mysteries (1978), R. Gordon Wasson, Albert Hofmann, and Carl Ruck proposed that kykeon was mixed with the ergot species Claviceps purpurea — a fungus containing LSD-like alkaloids, such as ergotamine, which grows on rye and barley. Hofmann also suggested an alternative hypothesis that kykeon might have been prepared from another species of ergot, Claviceps paspali, which did not grow on barley, but rather on the wild grass Paspalum distichum. 

Evidence has since emerged that provides possible support for this idea. Fragments of ergot were discovered in a temple dedicated to the two Eleusinian goddesses excavated at the Mas Castellar des Pontós site in Gironia, Spain dating to 300 BC. These fragments were found inside a vase and within the mouth of a 25-year-old man, providing evidence that ergot was consumed, suggesting it was an active ingredient of kykeon. Brian Muraresku cites this evidence in his book The Immortality Key: The Secret History of the Religion with No Name (2020), connecting the ritual consumption of the psychedelic drink kykeon to the origin of Christianity. Muraresku argues early Christians also participated in rituals using psychedelic brews (and that these were the origins of the Christian Eucharist). Thus, he sees Western civilisation rooted in the psychedelic experience. His work has helped to put the nascent fields of archaeobotany and archaeochemistry in the limelight.

To share what occurred at the Eleusinian Mysteries was punishable by death under Athenian law, so information about them is, understandably, scant. To avoid the death penalty, Plato described his mystical experience in cryptic terms, speaking of Eleusis in the Phaedrus as: the “most blessed of mysteries” where he experienced “a state of perfection” and “blessed sight and vision”.

At the climax of the ceremony, attendees were given the title epoptes, which roughly translates as ‘The one who has seen it all’. After the ceremony, initiates claimed that life continued after death. For instance, after his initiation, Sophocles said, “trice blessed are those among men who, after beholding these rites, go down to Hades. Only for them is there life [after death]; all the rest will suffer an evil lot.” The ritual, therefore, seemed to engender an alternative attitude towards death and dying.

The experiences of attendees at the Eleusinian Mysteries, in many ways, bear a resemblance to the psychedelic experiences recorded in surveys and clinical trials. Many people who use psychedelics report acquiring knowledge of ‘ultimate reality’ and overcoming the fear of death. Many belief changes that happen following psychedelic mystical experiences are philosophical in nature (see here, here, and here). It may be possible that some of the key ideas or systems of thought found in ancient Greek philosophy were inspired by experiences with kykeon. 

Plato himself said in the Phaedo that he was inspired by the Mysteries. The contemporary philosopher Peter Sjöstedt-Hughes notes that Plato, in the Phaedrus, saw the body as a prison, which the Mysteries can help you escape; the latter wrote that he was permitted to “the sight of perfect and simple and calm and happy apparitions, which we saw in the pure light, being ourselves pure and not entombed in this which we carry about with us and call the body, in which we are imprisoned like an oyster in its shell.” The Phaedrus also includes his theory of metempsychosis (otherwise known as the transmigration of souls, or the reincarnation of one’s immortal soul into another body after death, with the number of souls being fixed).

And in the Phaedo (or On the Soul), after mentioning the Mysteries (and saying the initiates have “practiced philosophy in the right way”), Plato introduces the landmark notion of substance dualism, or the idea that the body and soul are separate, distinct substances. Sjöstedt-Hughes states in an article for Quartz: 

Under psychedelic experience, you can completely lose the link between ‘you,’ yourself as a body; and ‘you,’ yourself as the person that you think you are, including your memories. There’s this loss to the self, and the self is often associated with the body, so I can certainly see why a psychedelic experience would incline one towards a more dualistic view of the world.

“[Alfred North] Whitehead famously said, ‘Western philosophy is a series of footnotes to Plato.’ If Plato was inspired by psychedelics, then the whole of the Western canon is unwittingly inspired by these experiences,” Sjöstedt-Hughes adds. However, according to traditional scholars, the altered states of consciousness and euphoria experienced at Eleusis were more likely caused by the participants arriving in a famished state after a 3-day fast and dancing for several hours – a combination that can result in self-induced visions and hypnotic trances.

Outside the realm of speculation and uncertainty, Sjöstedt-Hughes has offered a fascinating exposition on the psychedelic influence on philosophy. As well as Plato’s ideas, Sjöstedt-Hughes looks at how altered states induced by drugs influenced the thought of:

• Thomas de Quincy
• Humphry Davy
• Friedrich Nietzsche
• William James
• Walter Benjamin
• Aldous Huxley
• Ernst Jünger
• Octavio Paz
• Herbert Marcuse
• Jean-Paul Sartre
• H.H. Price
• A.J. Ayer
• Michael Foucault

Sjöstedt-Hughes believes that for those who are able to have a positive psychedelic experience on psychedelics, taking these drugs can be as profound as reading Nietzsche. Both the German philosopher and the substance can lead to questioning one’s cultural values and societal rules. Psychedelics may also improve the reading of philosophy. After all, James claimed he only fully understood Hegel after taking nitrous oxide.

The work of Sjöstedt-Hughes deserves greater attention, as he has played a key role in the modern growth of the philosophy of psychedelics. Sjöstedt-Hughes is an Anglo-Scandinavian philosopher specialising in the thought of Spinoza, Whitehead, Schopenhauer, Nietzsche, and Bergson within the philosophy of mind, with a special interest in psychedelic states of consciousness and panpsychism (the view that everything has a mind or mind-like aspect). 

Sjöstedt-Hughes’ PhD thesis is titled Pansentient Monism: Formulating Panpsychism as a Genuine Psycho-Physical Identity Theory, which presents a variation of panpsychism as a solution to the mind-matter problem, or the problem of how mind and matter relate (also known as the hard problem of consciousness). He has two books published, Noumenautics: Metaphysis, Meta-ethics, Psychedelics (2015) and Modes of Sentience (2021), both published by Psychedelic Press UK, and he co-edited the book Philosophy and Psychedelics: Frameworks for Exceptional Experience (2022), published by Bloomsbury, which also includes an essay he penned: ‘The White Sun of Substance: Spinozism and the Psychedelic Amor Dei Intellectualis’. 

You can find a list of Sjöstedt-Hughes’ academic and non-academic work on the philosophy of psychedelics here. His article ‘On the need for metaphysics in psychedelic therapy and research’ was published this year in the journal Frontiers in Psychology. In this article, he argues “integrating metaphysical experience requires recourse to metaphysics” and that certain metaphysical systems can help make psychedelic experiences “more intelligible, comprehensive, viable, and acceptable to participants [in psychedelic therapy]”.

In terms of Sjöstedt-Hughes’ wider influence on this subdiscipline, he (along with fellow philosopher Christine Haukseller, who also co-edited Philosophy and Psychedelics) has designed and taught the very first academic module on the philosophy of psychedelics (at the University of Exeter). This module covers:

• Philosophy of mind, consciousness, and psychedelics
• The biopolitics and bioeconomy of psychedelics
• Creativity and aesthetics vis-à-vis psychedelics
• Perennialism and Contextualism: Western mysticism and Non-Western Indigenous approaches
• Metaphysics and psychedelics: Interpreting psychedelic experience through metaphysical systems
• Transpersonal and environmental ethics and psychedelics

On the programme, The Guardian reports that the philosophical side of the course covers “the insights into consciousness and metaphysics that psychedelics give – and discussions of decolonising psychedelic research and practice, including an anthropological look into cultures which have used psychedelics for centuries.” The aim of the programme is to upskill and educate healthcare workers and therapists on the emerging potential of psychedelics. And the interdisciplinary nature of it “will situate this medicinal progress within a cultural, neuroscientific, and philosophical context – analysing the ethics and politics of the current ‘psychedelic renaissance’, as well its impact on understanding consciousness,” says  Sjöstedt-Hughes.

Along with Hauskeller, Sjöstedt-Hughes has also created the Philosophy of Psychedelics Exeter Research Group. He organised the Philosophy of Psychedelics Conference in Exeter, gave a highly viewed TEDx talk titled ‘Philosophy and psychedelics’, and has appeared in a number of podcasts, media outlets, and debates, helping to communicate how the psychedelic experience relates to a range of philosophical ideas. He continues to lecture at the University of Exeter on these topics. I highly recommend giving him a follow on Twitter.

Another important figure in the philosophy of psychedelics is Chris Letheby, Lecturer in Philosophy at the University of Western Australia. He specialises in philosophy of mind, philosophy of cognitive science, philosophy of neuroscience, and epistemology. His research has focused on the use of classic psychedelics in neuroscience and psychiatry. 

In several articles and his book Philosophy of Psychedelics (2021) – published by Oxford University Press and the first scholarly monograph in English devoted to the philosophical analysis of psychedelics – Letheby argues that psychedelic insights and spiritual experiences can be reconciled with naturalism, the philosophical position that the natural world is all there is. An open-access symposium on his book was published in 2022 by the journal Philosophy and Mind Sciences.

In his book, Letheby addresses clinical trials on psychedelic-assisted therapy, which find that the mental health benefits of these supervised psychedelic sessions seem to be mediated by mystical experiences (characterised by unity, ego dissolution, ‘cosmic consciousness’, and the transcendence of space and time). This prompts a philosophical concern: Do psychedelics benefit people by inducing false or implausible metaphysical beliefs about the nature of reality? 

Letheby, however, rejects this ‘Comforting Delusion Objection’. He argues that while such metaphysical ideas sometimes arise, they are not in fact the main driver of psychological benefits and change. Instead, Letheby stresses psychedelics produce lasting benefits by altering the sense of self and how people relate to their own minds and lives, and not by changing their views on the fundamental nature of reality. Moreover, as a philosopher who subscribes to the naturalistic worldview, Letheby proposes that psychedelic use can lead to genuine forms of insight and spiritual growth even if no cosmic consciousness or transcendent divine reality exists. In this way, the epistemic status of psychedelic therapy can be defended. He also makes the case for naturalised spirituality in an article for Psyche, drawing on the work of philosophers Jermone Stone and Thomas Metzinger.

Other contemporary philosophers who have analysed the psychedelic experience include the already-mentioned Metzinger, who discussed the effects of classic psychedelics in his books Being No One (2003) and The Ego Tunnel (2009). In the former, he argues the hallucinatory component of the psychedelic experience is “epistemically vacuous”, meaning it is not a reliable source of knowledge. Metzinger is a neurophilosopher who insists we should rely on the objective evidence supplied by the neurosciences. 

The anthropologist and historian of science Nicolas Langlitz has also made the case for there being a place for psychedelics in philosophy. He writes that “there can be and there already is a very small place for psychedelics in philosophy, on which we could build by bringing perennial philosophy into conversation with empirically oriented forms of research, such as neurophilosophy and ethnographic fieldwork on “consciousness cultures.””

In addition, Langlitz provided some of his philosophical reflections on psychedelics in his book Neuropsychedelia (2012), published by University of California Press. Here he notes that researchers on psychedelics have offered a neurobiological reinterpretation of Huxley’s ‘reducing valve’ theory expressed in The Doors of Perception (1954), influenced by the thought of Henri Bergson and C.D. Broad, which proposes that the brain limits the amount of information entering conscious awareness to prevent us from becoming overwhelmed by largely useless and irrelevant knowledge; so it exists for the sake of our survival. However, psychedelics, Huxley suggested, disrupt this mechanism, thereby producing a ‘perennial’ mystical experience, an unbounded state of consciousness that Huxley called ‘Mind at Large’. 

Scientists have associated this ‘reducing valve’ with the default mode network (DMN) in the brain, which shows reduced activity under the influence of psychedelics, allowing freer conversations between brain regions that don’t normally communicate with each other. Langlitz refers to this materialist reinterpretation of Huxley’s view as “mystic materialism”. This is a worldview that empahsises the metaphysical unity of the world, but situated within a naturalistic framework (which denies the existence of supernatural forces, laws, and entities). 

Huxley adopted a belief in the ‘perennial philosophy’ (philosophia perennis), inspired by psychedelics, which states that the essence of the world religions are universal beliefs and experiences. Leibniz, who uses the Latin phrase for this term, coined by Agostino Steuco in 1540, made the same case for the history of philosophy, arguing that essential truths have been and always will be found in every philosophical system. The perennial philosophy, or perennialism, is a metaphysic that, according to Huxley, “recognizes a divine Reality substantial to the world of things and lives and minds.”

We have so far explored some of the topics and issues involved in the philosophy of psychedelics. This subdiscipline matters because it raises questions important for psychonauts, researchers, and philosophers of mind, epistemology, metaphysics, neuroscience, psychiatry, mysticism, aesthetics, and existentialism. The psychedelic experience forces us to consider philosophical questions, such as:

• What is the fundamental nature of reality? Can psychedelic experiences provide support for certain philosophical positions on reality, such as animism (the widespread belief in the existence of distinct spirits or souls in nature), Idealism (reality is composed of ideas), pantheism (nature or the universe is God), substance dualism (the mind and body being are composed of different substances) panpsychism (consciousness exists everywhere), or the simulation hypothesis (consensus reality is a computer simulation)?
• Can psychedelics provide insights into other philosophical positions, such as anattā (the self does not exist/is an illusion), Nietzschean life-affirmation (a yes-saying to the world), certain ideas found in phenomenology (which studies the structures of experience from the first-person point of view), or perennialism? 
• Do psychedelics strengthen or weaken the case for nihilism? In other words, do psychedelic experiences bolster the existence of specific values or do they reveal the baselessness of all proposed values, meaning, and purpose?
• How can we judge if psychedelic insights are veridical or false? In other words, what is the epistemic status of psychedelic experiences?
• Do some aspects of psychedelic experience challenge the assumption of philosophical naturalism/materialism/physicalism? Or do the brain changes and subsequent subjective effects elicited by psychedelics actually provide support for a materialist conception of consciousness?
• How should we interpret personal encounters with God, a higher power, or a divine reality? We could offer theological, mystical, materialist, or pragmatist perspectives.
• What is the nature of time and space?

• The concept of cognitive liberty (the right of individuals to alter their consciousness)
• Biopiracy (also known as scientific colonialism), which refers to the unauthorised appropriation of knowledge and genetic resources of indigenous communities by individuals or institutions seeking exclusive monopoly of that knowledge or biological materials through patents or intellectual property (IP). This is a major issue in the psychedelic industry due to the proliferation of patents and IP sought by psychedelic companies.
• Some believe the accommodation of psychedelic medicine into a capitalist framework is an ethical issue, as it can risk putting profits before people. (Dr. Katherine MacLean, a former lead researcher and session guide for psilocybin research at Johns Hopkins University School of Medicine, and Brett Greene, co-founder of psychedelic company Adelia Therapeutics, both independently coined the term corporadelic, which MacLean says means “manifesting corporations to commodify psychedelic experiences”.) 
• The medicalisation of psychedelics may invoke a value-laden distinction between ‘proper’ and ‘improper’ uses of psychedelics, which itself can potentially undermine efforts to decriminalise or legalise psychedelic drugs (for non-medical uses).
• Ensuring harm reduction practices, like providing public education on risks, if psychedelics are legalised and become commercially available (as argued by ethicist Joseph Holcomb Adams).
• The ethics of psychedelic therapy, including issues like gaining informed consent to treatment that can lead to mystical experiences and radical and long-lasting shifts to outlooks, values, beliefs, priorities, and personality traits (which has been explored by neuroethicist Eddie Jacobs and professors William R. Smith and Dominic Sisti); respecting autonomy (such as therapists not forcing their metaphysical beliefs or personal interpretations onto patients before, during, or after psychedelic sessions); patient vulnerability (owing to enhanced suggestibility); unique power dynamics; the duty of therapists to protect patients during and after psychedelic experiences; and equitable access to treatment (which may be frustrated by for-profit psychedelic companies).

Conclusion