The West is currently in the middle of a “psychedelic renaissance,” a movement characterized by a reemerging academic, medical, and cultural interest in psychedelic substances, accompanied by efforts to decriminalize and legalize these substances. As a philosophy student, the element that fascinates me most about these developments is that they seem to be forcing scientists outside of their territory. Study subjects inside fMRIs report becoming one with the Universe. Psychedelic therapy patients attribute their miraculous recovery to an encounter with an ultimate reality, perhaps with God (however one might define “God”). In surveys, people report their psychedelic experience was more real than their day-to-day experience of reality (Barrett & Griffiths, 2018; Yaden et al., 2017). It goes without saying that when a person starts talking about “ultimate reality” and “God,” we are far beyond the scope of traditional, mainstream science. What was initially a topic of research for only psychologists and neuroscientists, suddenly became a matter of interest for philosophers, and, specifically, metaphysicians – philosophers who study the ultimate nature of reality (whatever that may mean). If one starts introducing religious terminology, suddenly theologians are also involved. Most scientists working with psychedelics simply avoid discussing these matters, or stick to naturalistic explanations. This is a perfectly fair attitude. Indeed, one might argue that it is precisely this attitude that made the psychedelic renaissance possible: if scientists were stuck arguing over, say, the metaphysical status of psychedelic experiences, physical and psychological research on the matter would probably not be progressing as rapidly. But for how long can we keep avoiding the questions about reality and the meaning of existence that the use of psychedelic substances seems to inevitably raise?

For the sake of simplicity, let us categorize all of these (literally) extra-ordinary psychedelic-induced phenomena as “mystical experiences”. Defining a mystical experience is a surprisingly complicated matter, but for our purpose a mystical experience can be understood, somewhat poetically, as an experience of “oceanic boundlessness” (Freud), of union with the “divine ground” (Eckhart), “a state of mind that is cosmic in scale” (McKenna). I am inclined to think of a mystical experience as the experience of losing one’s sense of being a subject opposed to an external world, as the destruction of the internal-external, subject-object dichotomy. These kinds of experiences, once regarded as mere delusions, unworthy of attention, are now a common element in many scientific papers. What I want to do in the following is focus on the so-called “noetic quality” of psychedelic-induced mystical states, i.e. the fact that these mystical experiences seem to carry a certain authority; the fact that they are often considered “objective,” or “real” by those who have them. This feature, I argue, poses the biggest challenge for scientists working with psychedelics. After reviewing some of the evidence, I will make some suggestions on how scientists from different fields may deal with these data.

In a recent study by Timmermann et al. (2021), psychedelics were shown to induce significant changes in one’s beliefs about reality, consciousness, and free-will. Specifically, psychedelics seem to naturally lead a person to abandon strictly materialistic views (i.e., views that consider everything that exists, including mental properties, to be reducible to matter) and endorse positions closer to dualism (the idea that the physical and the mental are irreducible to one another), or even idealism (the belief that everything that exists is essentially mental). It is also now commonly acknowledged that psychedelic-induced mystical experiences are directly correlated to improvements in mental health in therapeutic settings: a patient who has reached a mystical state is far more likely to see lasting improvements in their mental health. Patient reports from these studies indicate that what people witness during their psychedelic-induced mystical experience is critical in allowing them to overcome their issues (Letheby, 2021, p. 24). Another series of seminal studies where these kinds of experiences play a major role were carried out on patients with life-threatening cancer by Roland Griffiths and his team (2016) at Johns Hopkins. Here, a high dose of psilocybin (the main psychoactive compound in “magic mushrooms”) was shown to significantly decrease most patients’ fear of death. Psychedelic-induced mystical experiences seem to have convinced participants of the existence of life beyond subjectivity and therefore, one might say, of life beyond death. It is clear that in Griffiths’ research, as much as in the other two study cases presented above, psychedelic-induced mystical experiences cannot have been lived as delusions. For them to change one’s metaphysical beliefs, to significantly improve a person’s mental health, or to even eliminate one’s fear of death, these states must have been experienced as real, in a very radical sense. The question now is, what should a scientist do with this information, if anything?

The answer really depends on the scientist. If a neuroscientist, for example, wants to study the neural correlates of psychedelic-induced mystical experiences (i.e., what happens in the brain during these experiences), metaphysical or theological speculation may not be necessary. An interdisciplinary approach might certainly help scientists focusing on the physical brain better understand the scope of their research. However, I do not believe ignoring personal reports of mystics and psychonauts would be particularly detrimental to their inquiry.

Things are different, however, for those researchers trying to unveil the nature of consciousness – whereby “consciousness” I mean the mere fact of experience, the fact that things are appearing. What makes the study of consciousness particularly complicated is that one cannot study it from a third-person perspective as virtually any other object of scientific research. Again, one can certainly observe the neural correlates of consciousness, but many (including myself) believe that no study of the brain will ever explain consciousness, precisely because of its subjective nature. If this is correct, then a scientist working on consciousness must take into consideration psychedelic-induced mystical experiences. The reasoning goes like this: our day-to-day state of consciousness – characterized by the experience of external macro-objects – feels real. It can be intersubjectively corroborated (we can both touch and see the same table in front of us), but the feeling of realness remains fundamentally personal, private. It could not possibly be otherwise. If enough people insist that different states of consciousness (say, states in which there is no difference between internal and external) feel just as real as our day-to-day experience of reality, then these states should be considered by our researchers as important as our common state of consciousness. In sum, if one wants to study consciousness, one cannot focus only on one state of consciousness among many and, if that is the case, metaphysical discussion becomes unavoidable, thus propelling scientists into a territory that traditionally belongs to philosophers.

The same point can be extended, even more effectively, to those scientists focusing on the nature of mystical experiences: explaining what happens to the physical brain will not really explain much about the mystical experience itself. As William James – the father of the modern studies on mysticism – asserted over 100 years ago, all conscious and mental states have physical correlates in the human body, but studying these bodily phenomena will not necessarily help us explain the experiences they are associated with. Subjectivity cannot be explained objectively; and explaining the physical will not explain the mental, even though the two are certainly connected.

There is, however, one area of psychedelic research in which, more than the others, the boundaries of traditional science seem to be breaking: psychedelic-assisted psychotherapy. Here, one can simply not avoid taking into consideration the value that psychedelic and mystical states have for the patients, or the beliefs that they attach to their experience. Say, for example, that by the end of a session a patient is fully convinced that it was a communion with “God” that obliterated their depression. A neuroscientist could (perhaps) simply forget about this statement, but a therapist or a psychologist could not. This is especially true given how increasingly common these kinds of statements are becoming. It is not by chance that many therapists working with psychedelic substances are abandoning more “physically-grounded” frameworks (e.g., cognitive behavioral therapy), in favor of what were once considered controversial forms of therapy. For example, Stanislav Grof’s transpersonal psychology is now widespread in psychedelic circles, retreats, and clinics. Similarly widespread seems to be psychoanalysis, especially in the form advanced by the Swiss thinker Carl Jung. What I believe makes Jung particularly fascinating for psychedelic therapy is that, throughout his work (as a clinician and philosopher), he considered the mental world, in all its forms, at least as real as the physical world. For him, every mental image, every memory, every conscious and subconscious thought, etc. is to be taken extremely seriously, whether we want to help people or understand the nature of the world.

To conclude, let us condense this commentary into two practical pieces of advice, the first for “hard” scientists, such as neuroscientists, and the second for therapists. Neither of these suggestions is particularly revolutionary or unheard of, but they seem to me worth reiterating until they are finally taken seriously and become mainstream. First, I believe the study of the nature of consciousness, of mystical experiences and of experience in general, should be interdisciplinary. Specifically, hard scientists in these fields should be in constant communication with metaphysicians and historians with an expertise in mysticism and religion. If, as I argued above, the sense of certainty that psychedelic-induced mystical experiences carry ought to be taken seriously, then scientific data and philosophical speculation will be as important as reports of mystics throughout history. Second, when it comes to psychedelic-assisted therapy I believe one of two routes is advisable. A first alternative is to drop a materialism-based framework in favor of one that is more open to the reality of psychedelic-induced mystical experiences (e.g. Jungian psychoanalysis). A second option is to drop the idea of truth altogether. What if the experiences that the subjects report are not actually real? What if they are, as Chris Letheby recently phrased it, “comforting delusions”? Sometimes people just want to live happy and healthy lives, free from anxiety, depression, or even the fear of death. Sometimes truth is not the absolute priority. Sometimes, all a relentless search for truth does is make people unhappy.

I do not know whether the gradual decriminalization and normalization of psychedelic substances will break science, with its materialistic framework and rigid methods, from the inside, or if it will simply force it to slightly adjust to these unique phenomena. What I can confidently say is that, as time passes, reports of people becoming one with the universe, or of meeting God under the effect of psychedelics will become more and more common. As they do, it will become harder and harder for scientists working with these substances to simply ignore them.


Barrett, F. S., & Griffiths, R. R. (2018). Classic Hallucinogens and Mystical Experiences: Phenomenology and Neural Correlates. Current topics in behavioral neurosciences, 36, 393–430.

Griffiths, R. R., Johnson, M. W., Carducci, M. A., Umbricht, A., Richards, W. A., Richards, B. D., Cosimano, M. P., & Klinedinst, M. A. (2016). Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. Journal of psychopharmacology (Oxford, England), 30(12), 1181–1197.

Letheby, C. (2021). Philosophy of Psychedelic. Oxford: Oxford University Press.

Timmermann, C., Kettner, H., Letheby, C., Roseman, L., Rosas, F. E., & Carhart-Harris, R. L. (2021). Psychedelics alter metaphysical beliefs. Scientific Reports 11(1):22166.

Yaden, D. B., Khoa, D., Nguyen, L., Kern, M. L., Wintering, N. A., Eichstaedt, J. C., Schwarz, H. A., Buffone, A. E. K., Smith, L. K., Waldman, M. R., Hood, R. W., Newberg, A. B. (2017). The Noetic Quality: A Multimethod Exploratory Study. Psychology of Consciousness Theory Research and Practice, 4(1):54-62.

About The Author

Alberto Cavallarin

Alberto did his Bachelors in Philosophy at Ca’ Foscari University (Venice, Italy) and is currently finishing a Research Masters in Philosophy at Utrecht University (Netherlands). He is graduating with a thesis titled “Mysticism, Metaphysics, Truth: Are Mystical Experiences Real?”

Learn more about Alberto and his work on Instagram: @alberto_cavallarin

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