Anthropologist Martin Fortier looks at reductionist and non-reductionist perspectives on ayahuasca entities.

Many people report encountering spirits and other extraordinary entities under the effects of ayahuasca and similar psychedelic substances. But are these entities actually real? A widespread view in the psychedelic counter-culture and among some unorthodox scholars is that they are very much real. In contrast, the majority of brain and behavioral scientists studying these substances suggest they are mere hallucinations or experiences of things that are not really there. By reducing psychedelic entities to brain processes, scientists have been accused of overlooking the experiential richness of visionary trips. More damningly, they have been charged with removing the essence or intrinsic value of psychedelic experiences.

My aim here is twofold. I want to demonstrate that common arguments launched against the scientific approach to psychedelic entities are misleading. I also intend to chart a general framework that can help rescue naturalistic research programs from the charge that they suck the life out of psychedelic experiences. Within such a framework, psychedelic entities can be studied and explained in natural terms without necessarily reducing their intrinsic value.

The Praiseworthiness of Nonexistence: Fictions Can Be Highly Valuable

In the 18th century, the philosopher David Hume remarked that statements about what is tell us nothing about what ought to be; in other words, moral statements cannot be derived from purely observational ones. Echoing Hume, the 20th century philosopher G.E. Moore put forward the concept of naturalistic fallacy; he was thus pinpointing demonstrations that intend to ground moral judgments (e.g., “x is good”) on factual ones (e.g., “x exists”). Doing so, Moore argued, is utterly fallacious.

The lesson we can learn from Hume and Moore is that factual judgments should be thoroughly detached from moral, ethical, or value judgments. This philosophical point is very intuitive indeed. For example, torture exists in the world, and yet we are willing to judge it immoral; similarly, peace in the world is nonexistent,and yet we are willing to judge it moral. More to the point, saying that psychedelic spirits do not exist does not imply that they have no value.

Three German philosophers of the 19th century—Immanuel Kant, Friedrich Nietzsche, and Hans Vaihinger—have greatly contributed to the realization that many of the things we take to be valuable lack existence. Many of our beliefs and experiences are colored by stories that contain models of the world that do not correspond to anything real. These fictions are to a large extent inescapable, and yet they are very valuable. You could hardly live a proper life without them. In his book The Philosophy of “As If,” Vaihinger highlighted the value of fiction with his principle of fictionalism. He stated, in rather abstract terms, that “[a]n idea whose theoretical untruth or incorrectness . . . is admitted, is not for that reason practically valueless and useless; for such an idea . . . may have great practical importance.” We have all sensed the deep value of finishing a great movie or novel and felt our perception of the world expand or unfold in new, important, and even practical ways. Having said this, I do not think we should value psychedelic experiences in the same way we appreciate movies or books. Similar to the relationship between myth and ritual, movies and psychedelic experiences have some overlap, but they are certainly very different things.

It appears that the debate about the (non)existence of psychedelic spirits has been fraught with two unfortunate pitfalls. The first is the naturalistic fallacy. This is the failure to recognize that describing psychedelic spirits or entities as brain processes does not presume what their value or importance is. The second is the inability to recognize that fictions can be practical and wonderful—that one can acknowledge the non-existence of an entity and simultaneously interact with it as if it were real. People who dismiss the approach of understanding psychedelic entities as brain processes have missed the pervasiveness of fictions in life. For instance, when beholding colorful paintings in a gallery, they do not realize that the colors they see are not real. Neuroscientists beholding the same paintings can enjoy them as much as anyone else even though they know these colors are the mere products of their brain activity. Knowing that your brain is essential to the process of appreciating beauty in art could even possibly bring an extra dimension of appreciation to the experience. The same occurs with ayahuasca spirits: one can successfully experience them as being there and exquisitely interact with them even if one thinks they are not supernatural entities but neurons firing in the brain.

Psychedelic Experience Explained by the Mind/Brain Identity

What do I mean exactly when I say that “psychedelic entities do not exist”? One thing I do not mean is that people’s experience of such entities is illusory. Some philosophers—called “eliminativists”—have argued that conscious experience is nothing but an illusion. For them, consciousness is not real. They argue that it seems to people that something real is experientially happening, but in fact there is really nothing. This is not at all the kind of view I wish to advocate. I take consciousness and its content to be perfectly real. When people hallucinate spirits, there is no doubt they really entertain the experiences they report. As a consequence, I do not deny the “experiential existence”—or weak existence—of psychedelic entities. I duly acknowledge that people perceive these entities, feel they are real, interact with them, etc. Weak existence is not the moot point of the present debate.

What is really at stake is whether psychedelic entities have strong existence. This kind of existence requires conscious experience to correspond to something real in the world. For example, when I see a table in front of me, I have the conscious experience of a table (the table exists for me; it possesses weak existence), and a table is really there in the world (the table exists in itself; it possesses strong existence). The correspondence between the content of consciousness (my experience of the table) and what is in the world (the physical table) suffices to conclude that the table possesses strong existence. By contrast, the spirit I encounter in an ayahuasca trip exists only in my experience. It is not to be found anywhere in the world; it possesses weak existence.

Now that non-existence has been defined, let us explore how to best conceive of the relationship between the mind (consciousness) and the brain (neurons) in psychedelic experience. As explained above, it would be a mistake to simply dismiss consciousness. A more satisfactory philosophical option is to say that conscious experience is something real, but that it can be reduced to brain processes. Reduction, here, should not be conflated with causation. Saying that neurons firing in the brain cause conscious experience would be misleading; it would imply that the mind (the effect) is something different from the brain (the cause). Reduction should rather be defined by identity—by an identity between the mind and the brain (this is why this theory is called the “identity theory” of consciousness). According to identity theory, conscious experience is the brain. For instance, having an ayahuasca vision and having specific assemblies of neurons firing in the brain is exactly the same thing. An intuitive way to conceptualize the identity between the mind and the brain is to resort to the content/vehicle distinction: neurons are nothing but the vehicle of the conscious content.

ayahuasca brew
The ayahuasca brew is typically made from boiling the vine Banisteriopsis caapi with the shrub Psychotria viridis.

An apparent shortcoming of the mind/brain identity theory is that it cannot properly account for “top-down” effects of the mind on the brain. For example, the neuroscientific study of meditation has demonstrated that mindfulness can change the biology of the brain. How can we make sense of such findings if the mind is identical to the brain? It is in fact easy to do so as long as we recognize that the identity theory is compatible with weak emergence. Let me explain. Strong emergence is the view that matter can give rise to something that is radically different from it. Accordingly, the mind will be said to strongly emerge from the brain if it is not reducible to the brain—the world will thus be made of two different substances, mind and matter. By contrast, weak emergence refers to the emergence of properties that belong to the physical realm and do not require the existence of a non-physical realm. This is the kind of emergence that physicists are studying. Weak emergence typically manifests itself in transitions between small and large scales. If weak emergence can occur when transitioning from small to big assemblies of neurons, we can then easily account for top-down effects. The meditating mind refers to big neural assemblies and the observed brain effects to small neural assemblies.

On a related note, recent research has shown the effects of psilocybin on depression are explained by the nature of the psychedelic experience (the mind level) rather than the neuropharmacological mechanisms at work (the brain level). A more naturalistic way to rephrase these findings is to say that psychedelic experience refers to big assemblies of neurons and neuropharmacological mechanisms to much smaller neural or molecular units. What is often meant by the mind is nothing but the content of large-scale units of the brain.

Practical and Ethical Implications of the Mind/Brain Identity

Why should we embrace the identity theory? There are many reasons to do so, and it would be too long to rehearse all of them. (For those interested, see Ullin Place’s book.) A rather intuitive reason for rejecting non-reductionist accounts of consciousness is that experience is not a good guide to existence. Experiencing ayahuasca spirits is not enough to infer that these spirits do exist. Let us consider this with a different kind of example. Our everyday experience teaches us that the earth is flat. It is only through inference and scientific reasoning that the errors of immediate experience can be overcome. Here, however, I will follow a different argumentative path; I will focus on the practical and ethical implications of the mind/brain identity.


A popular alternative to the reductionist account of psychedelic experience is Huxley’s reducing valve theory. Briefly, this theory compares the brain to a radio receiver and consciousness to electromagnetic radio waves. According to this theory, it is an error to claim that the dependence of consciousness on the brain is a proof that the former can be reduced to the latter, for a radio can be destroyed and the radio program can be stopped and yet the radio waves (i.e., analogically consciousness) will still be around in the air. This account of consciousness, which we will call non-reductionist, has been endorsed by many authors within the psychedelic counter-culture (e.g., Dennis McKenna, James Oroc, Rak Razam). The radio metaphor amounts to classical dualism, that is, to the view that two different substances exist separately and that one cannot be reduced to the other. This view implies that ayahuasca spirits have some autonomous existence beyond the brain.

Let us assume for a moment that the dualist account is correct. If it is, then no neurobiological science, regardless of how advanced it is, will ever be able to completely understand the workings of ayahuasca spirits and other psychedelic entities. Because neurobiology is only a science of the radio receiver, and as psychedelic entities involve the radio waves, neurobiologists will never be able to predict much about the psychedelic experience. Now this is a big problem if the promise is that psychedelic experience has huge therapeutic potential. If the ayahuasca experience is mainly determined by the will of autonomous non-physical entities, rather than neurobiological laws, then psychedelic therapies and psychonautic exploration will always remain hazardous. Not only will beneficial effects never be under control, but conversely it will be hard to ever get a grasp on the occasional side effects of those experiences.

Let us now assume that the identity theory is correct. If non-reductionist theories are wrong, then neurobiology should in theory be able to discover—in a more or less distant future—the main laws governing both the beneficial and harmful effects of psychedelic experiences. According to the identity theory, ayahuasca spirits are reducible to and identical with specific brain processes. At some point it should thus be feasible to take highly selective pills triggering exactly the kind of experience people are looking for, be it receiving therapeutic information from a spirit or just exploring the visionary world for scientific curiosity or its beauty. Ayahuasca experience will be safe and on-demand.

In sum, ayahuasca spirits will turn out to be truly valuable only if the laws governing them can be studied and discovered and if the identity theory is thereby corroborated. As we can see, the debate between the reductionist and the non-reductionist account of the psychedelic experience is far from merely metaphysical; it has important ethical and practical implications. Each account makes specific predictions as to what the development of psychedelic neuroscience will look like. The future will tell whose predictions will actually manifest.

Stay Updated on All things Ayahuasca with our Monthly Newsletter!

We respect your privacy.
Martin Fortier
Latest posts by Martin Fortier (see all)