The Brain, In Theory Romain Brette Princeton Univ. Press (2026)
What is a brain? The question might seem obvious, but it is not trivial. Neuroscience has progressed in the past century, with the development of sophisticated techniques to measure and manipulate brain cells, neural circuits and even animal behaviours. Yet how the brain actually works still eludes us.
In The Brain, In Theory, neuroscientist Romain Brette deconstructs the predominant model of the brain, which treats the organ like a computer. He concedes that engineering metaphors can be useful but argues that they are often vague, incoherent and misleading — failing to capture animal cognition, for example. The reason is simple: real brains are not engineered. Brette aims to breathe life back into brain science by focusing the study of the nervous system on biology. The task is daunting, but Brette’s take-down of the field’s dominant theoretical frameworks is systematic.
Faulty thinking
First, he tackles the idea that brains and life in general can be explained using mechanistic concepts. Brains are not programmable machines, Brette contends, because neurons do not follow fixed rules or commands, cannot be modified to function arbitrarily and don’t implement computations as such. Nor is neural activity a code, in which one variable is mapped directly to another (as happens in Morse code and Braille). The firing rate of neurons can vary depending on the details of sensory stimuli, such as the orientation of an observed shape or the type of task being performed, and when and how it is being completed. In other words, although scientists can infer links between brain activity and external variables, this does not mean that the organism that they are studying is doing that as well.
Can consciousness ever be understood — this side of death?
Another doctrine that Brette rebuts is neuro-computationalism — the idea that the mind is a kind of software running on neural hardware, acting like a computing device. This reductive idea suggests that all mental capacity is merely a series of calculations. It treats the brain as if it is an analytical philosopher, a machine evaluating logical propositions. But this is a faulty anthropomorphic projection, conflating the tools that scientists use to study nature with nature itself.
Brette also seeks to extinguish the idea that the brain processes information. He refers to this as “epistemic phlogiston”, a hypothetical substance that was invented to explain the very properties it has by definition. Many neuroscientists do think of the brain as an organ that extracts and processes information. But Brette disagrees. Technically speaking, information indicates the level of uncertainty of a specific event, but that tells us little about how the brain works out a signal’s meaning.
In sum, Brette abhors the idea that the brain is an evolved biological machine. If he is right, then attempting to reverse-engineer it — the holy grail for most neuroscientists — is a deeply flawed enterprise. Brains are not designed and assembled, they evolve and develop. Neurons are not mechanical components but living units that belong to the whole body. Talking life to an engineer is like talking love to an accountant.
An ecological perspective
If a brain isn’t a machine, what is it? In his framework for cognition, Brette preserves only what he calls embodied information. This is information that is tied to the body and actions of an organism in its specific environment. He thus replaces concepts of computation and representation with those of interaction and embodiment. Cognition, he asserts, is knowing by doing — an idea that is not new but is insightful.
Many people have no mental imagery. What’s going on in their brains?
His perspective on the mind is ecological: our brains don’t compute, they contemplate a world of possibilities for action. When a person sees a chair, they do not categorize it abstractly, but instead anticipate the movements that they would need to perform to sit in it. Indeed, philosopher Henri Bergson described perception as “virtual action”1. Rather than prediction, Brette speculates that anticipation is the core concept of cognition and life, although this promising thought proposed towards the end of the book needs further explanation.
He concludes by emphasizing that the principle that rules living brains is organization. He sees brain activity as “the collective behaviour of a colony of living entities, rather than a distributed computer”. Organisms grow, divide, mutate and self-organize. They are integrated, embodied and deeply embedded in their environment. Yet they are also autonomous, goal-driven, proactive and creative. In such a process-centred view of life2, brains and minds are considered inherently dynamic, rather than as static things that change mechanically. This approach revitalizes the role of biological processes in cognition by turning our conception of stability versus activity upside down. The real challenge is to explain constancy in a world where nothing remains static.
