“If the doors of perception were cleansed, every thing would appear to man as it is, Infinite. For man has closed himself up, till he sees all things thro’ narrow chinks of his cavern.”
In our everyday life, we inhabit a low-resolution version of the world. Cognition is expensive, and so when we live in familiar surroundings, our brains go into energy-saving mode. We operate on the level of what Buzsáki calls the good-enough brain, and which can be roughly equated to Kahneman’s system one: a level of brain activity that is not particularily concerned with getting to the bottom of the truth, but rather optimized for a cognitive activity that lets us survive with the minimal energy cost.
But as William Blake says, alluding to Plato’s allegory of the cave: this makes us spend our daily lives closed off at the base of a cavern, out of touch with the light of Plato’s transcendental realm of ideas, with what Blake calls the Infinite.
The Bayesian brain hypothesis details how cognition lends itself to a statistical interpretation, grounded in Bayes’ law: every perceptual act consists of the integration of sensory data into a prior framework, defined by Bayesian priors, via posterior inference. The confidence in these priors is in technical terms given by their precision.
According to Kant (I wrote a short introduction here), our subjective perspective on the world is filtered through what he conceived of as an a priori perceptual structure. If we want it or not, we perceive everything filtered through the lens of the structure of our subjectivity. The parallels to Bayesian priors are no coincidence: our world model determines how we perceive the world, while the Kantian “Ding an sich”, the “Thing in itself”, eludes our grasp and lies beyond our perception.
The Bayesian brain hypothesis further proposes that our knowledge of the world is structured in hierarchical Bayesian models (as I explain in more detail here). Based on these models we can cast predictions about the future state of the world. Our every-day perception of the world is determined by our already existing models that define a contextual framework for interpreting reality. We are, as Terrence McKenna nicely put it, spending our lives adrift in context.
If there is a mismatch between prediction and sensory input, prediction errors (weighted by the precision of the model/our confidence in our model) are propagated through our brain, updating our models layer by layer.
The worse the prediction, the larger the error, and the larger the update. A simple prediction error can manifest itself in trivial matters: I expected my friend to wear a black shirt, but she is wearing a red one, so my brain updates its model of the shirt my friend is wearing. But if a more consequential prediction is wrong, this can also lead to pretty dramatic transformations of my world model: if I expected to spend the rest of my life with my girlfriend, but suddenly she broke up with me, my whole outlook on life has to change.
Our ignorance defines the boundaries of our world model. Everything within our world model is the known, everything outside the world model is the unknown. It is clear that we are necessarily ignorant about significant portions of the world. We simply cannot know everything that is going on. Otherwise, our brains would have to be as large as the universe itself: they would have to be the universe itself.
A natural consequence of this is that our phenomenological world decomposes into a structured, predictable/predicted part and an unknown part, associated with chaos. Research into brain lateralization has shown (see The Master and his Emissary by Iain McGilchrist for a fantastic account) that the left hemisphere is primarily responsible for abstract, ordered internal representations of the world, while the right hemisphere is, roughly speaking, more responsible for the experience of the unique, the novel, the chaotic, of something beyond our grasp. This experience of the unknown can appear to us both frightening and exhilarating (similar what Eliade calls the experience of the Sacred, as I discuss here). It contains both opportunity and threat, and accordingly, humans are both order-loving and exploratory creatures.
Ignorance saves energy because it prioritizes things we need to know against things we can afford not knowing about, but at the same time ignorance comes at a cost: if there is something unknown lurking out there that could pose a threat, our brains switch into exploratory mode. When we are confronted with our own ignorance, and our predictions about the world clash with reality more dramatically than usual, our right hemisphere gets into contact with the unknown. According to Blake, man has closed himself up, or rather evolution has closed us off against the Great Unknown lurking at the edge of perception. But while it eludes our grasp, we sometimes get an overwhelming sense that there is something there, get a glimpse of a transcendent reality looming beyond our model of the world.
The greater the doubt, the greater the awakening; the smaller the doubt, the smaller the awakening. No doubt, no awakening.
C.C.Chang, The Practice of Zen
In Zen Buddhism, a kōan (公案) is a story, question, or statement which is used to provoke the “great doubt”, a state of mind which overcomes all rational interpretations, opening up an experience of Satori, of spontaneous enlightenment. In Bayesian terms, this can be interpreted as deriving from artificially induced prediction errors. Large enough prediction errors relax our priors because they signal to the brain that the priors were wrong. They thus shift us into a mode of cognition less influenced by prior models, less influenced by what Zen philosopher Suzuki calls the old accumulations of intellect.
Error is the place where the transcendent reveals itself.
Zen Buddhism is only one example: many spiritual and shamanic traditions actively seek out transcendent experiences as a means to explore the unexplored. Aldous Huxley used William Blake’s phrase as the title of his famous and influential essay The Doors of Perception (which the band The Doors was named after), detailing his mescaline experiences in the 1950s. New studies show that psychedelic substances reliably invoke experiences of a transcendental nature (see here for my overview of current research). Carl Friston and Robin Carhart-Harris recently attempted to integrate the psychedelic experience into a Bayesian framework by proposing the REBUS model (relaxed beliefs under psychedelics), which details how psychedelics work to relax the precision of high-level priors or beliefs, and therefore make us cognitively less “closed up”: predictions errors do not get stuck on lower layers of the hierarchical world model, but rather roam more freely and light up our brain with a strong feeling of contact with an unknown reality.
The question remains: what exactly do we experience when we experience this unknown, transcendent reality?
In Bayesian terms, the transcendent experience is related to a state when all priors are relaxed, when we leave behind our “earthly” perceptions and our “earthly” way of seeing things, when we experience the world without any preconceived notions, as fresh and incomprehensible as a newborn would. Transcendent experiences point to something we have a hard time understanding, triggered by something akin to an “error” in our world model. And while these experiences are hard to conceptualize, they have exerted great fascination over mankind throughout the centuries.
Our species has been trying to map out these loftier realms of experience for a long time, often interpreting them in a spiritual and religious context, but also through the world of art. According to Carl Jung, metaphysical concepts of the Divine, as represented in theology and mythology, can be understood as representing universal features of the psychic experiences of the transcendent. That can make it tricky to disentangle what they mean theologically versus what they mean scientifically.
We are nothing; what we search for is everything.
The German idealist philosophers believed that it was the task of the genius to travel into unexplored transcendental realms and grapple with representing traces of them in art, be it in poetry, music, or painting. In contemplating great works of art, we could get into contact with this reality.
Art and metaphysics are therefore in a sense remnants of our long struggle of coming to terms with the nature of transcendent experience, of coming to terms with an experience of something that both feels manifestly real and manifestly beyond our conceptual understanding: they attempt at opening up the doors to a form of contact between us and the Unknown, of a dialogue between us and the Unknown.
It is peculiar that so much of our cultural heritage and our search for meaning in the universe is centered around types of experiences that we do not quite understand. Maybe their fascination lies precisely in the fact that they continue to elude our grasp.
The advances of neuroscience give us a new angle on how our perception works, and on how we can integrate the realm of transcendent experience into a scientific framework. Maybe these new tools can also help us map out transcendent experiences in a more secular language, and talk about their meaning and their potential in a scientific way. Because while they may seem incomprehensible to us, we are beginning to understand them as arising from the cognitive make-up that constructs our subjective universe, and from the functions that determine how we operate in a complex world full of threat and opportunity.
But perhaps at the same time, there will always remain something mysterious about them: because on an experiential level, the transcendent state leaves all concepts behind. It can feel both phenomenologically irreducible and incredibly real to us. And maybe that’s alright. Maybe it actually makes a lot of sense to be left feeling in awe at a universe that is infinitely more complex and rich than our models of it could ever be.