Three pounds, or about 1.4 kilograms. That's all the human brain weighs—roughly the same as a cabbage from the grocery store. Yet that piece of tissue somehow produces the swelling feeling in your chest when you listen to a Beethoven symphony, the anxiety you feel about a lover, the hope you hold for tomorrow. At least, that has been the working assumption behind modern neuroscience.
In April 2026, at the 15th "Behind and Beyond the Brain" symposium hosted by the BIAL Foundation in Porto, Portugal, Christof Koch, a meritorious investigator at the Allen Institute, directly challenged that assumption. Koch proposed that consciousness may not be something the brain "produces" at all, but rather a fundamental property of reality itself. In an unpublished essay, he writes: "Science explains nothing about how three pounds of matter—just another piece of furniture in the universe, obeying the same laws of nature as everything else—can love, hate, dream, imagine, fear, and hope for the future."
What makes this statement noteworthy is Koch's own background. He held professorships at MIT and Caltech and has led research into the neural correlates of consciousness for more than three decades. In 2016, he published a widely cited review in Nature Reviews Neuroscience showing that the neural correlates of consciousness are localized in a posterior cortical "hot zone" (Koch, Massimini, Boly et al., Nat Rev Neurosci 17, 307–321, 2016). The very person who has spent his career searching for consciousness inside the brain is now suggesting that the direction of the search itself may be mistaken.
A "Hard Problem" That Has Resisted Solution for 30 Years
To understand Koch's proposal, it helps to know the structural impasse that consciousness research has faced for decades.
In 1995, philosopher David Chalmers, in a paper titled "Facing Up to the Problem of Consciousness" published in the Journal of Consciousness Studies, divided the problem of consciousness into "easy problems" and the "hard problem." The easy problems concern functions explainable through computational mechanisms and neural circuits—attention, memory integration, behavioral control, and the like. The hard problem asks why physical processes are accompanied by subjective experience at all. When you see a red rose, why does the quality of "redness"—the qualia—arise at all? No matter how precisely we describe patterns of neural firing, that description never seems to contain the felt sense of experiencing something.
Over these thirty years, neuroscience has made enormous progress on the easy problems. Through fMRI, EEG, and intracranial electrode recordings, researchers have identified one correlate after another of conscious perception in brain activity. But an accumulation of correlations does not answer the question of why those correlations exist in the first place. What Koch's essay points to is precisely this fault line.
Koch further argues that three areas have recently deepened this fault line. First, the limits encountered in attempts to fully reduce subjective experience to physical mechanisms. Second, questions raised by modern physics about the nature of reality itself (such as the measurement problem in quantum mechanics). Third, the persistent existence of phenomena that resist explanation within existing frameworks—near-death experiences, mystical experiences, and terminal lucidity.
In an interview with ScienceAlert, Koch noted that roughly 10% of hospital patients resuscitated from cardiac arrest report near-death experiences. While these experiences don't "prove" that consciousness exists outside the brain, Koch argues they point to gaps in our existing explanatory frameworks—gaps that deserve serious investigation.
Integrated Information Theory as a "Mathematical Bridge"
As an alternative to materialism, Koch invokes analytic idealism along with Integrated Information Theory (IIT), the framework he uses to give this philosophical position scientific formulation.
Idealism is the philosophical position that consciousness or mind is fundamental to reality, with the material world being secondary. Koch is attempting to reexamine this tradition—tracing back to thinkers like Berkeley and Hegel—in a contemporary scientific context. IIT is an attempt to give this philosophical stance mathematical footing.
The core idea of IIT is this: a system possesses consciousness when it "integrates" information. Integration refers to the property whereby a system as a whole exerts causal influence exceeding the sum of its parts. IIT formalizes the degree of this integration as a quantity called (phi), and claims that any system with greater than zero has some form of subjective experience.
IIT was first formulated by Giulio Tononi in 2004 and has since developed through to version 4.0 (Tononi, Boly, Massimini, Koch, Nat Rev Neurosci 17, 450–461, 2016; Albantakis et al., PLoS Comput Biol, 2023). Koch is one of the theory's leading proponents, and in his 2024 book Then I Am Myself the World, he argues that, based on IIT, current AI systems like ChatGPT possess only the faintest trace of consciousness.
| Materialism (Physicalism) | Analytic Idealism + IIT | |
|---|---|---|
| Status of consciousness | A byproduct or emergent property of brain activity | A fundamental property of reality |
| Role of the brain | Generates consciousness | "Shapes" or "filters" consciousness |
| Response to the hard problem | Assumed to be solvable in the future through physical explanation | The framing of the problem itself is mistaken (no need to derive consciousness from matter) |
| Falsifiability | Indirectly tested through identification of neural correlates | In principle testable through measurement of (IIT's claim) |
| Current state of evidence | Over 30 years of accumulated correlational research | Near-death experiences and terminal lucidity presented as gaps in explanation |
As this table shows, the decisive difference between the two frameworks lies in the ontological status they assign to consciousness. Under materialism, consciousness is an "output" of the brain; under idealism, the brain functions more like a "receiver" of consciousness. In his interview with ScienceAlert, Koch was careful to note that he does not deny the brain's indispensable role in consciousness—it is well established that injury, disease, anesthesia, and electrical stimulation can dramatically alter conscious experience. What he questions is whether the brain "creates" consciousness, or whether it instead "shapes" something more fundamental.
An Adversarial Collaboration Revealed That Neither Theory Is Fully Correct
Recent large-scale testing has shown that IIT is not the only candidate theory in consciousness research. In 2023, an "adversarial collaboration" funded by the Templeton World Charity Foundation directly compared the predictions of IIT and the Global Neuronal Workspace Theory (GNWT, a competing theory led by researchers including Stanislas Dehaene), using third-party labs with no stake in either theory and 256 test subjects.
The result was close to a draw. IIT's prediction that posterior cortex would show superior decoding accuracy for conscious content was supported, while data on synchronization patterns between the prefrontal cortex and visual areas favored GNWT's predictions. The biggest challenge for IIT was that sustained synchronization within the posterior cortex was not observed to the degree predicted. For GNWT, the failure to detect prefrontal cortical "ignition" upon stimulus offset was a significant blow.
This outcome suggests that no existing theory offers a complete account of the neural basis of consciousness. It is against this backdrop of theoretical deadlock that Koch is raising doubts about the materialist framework itself.
An Experience on a Beach and the Limits of Science
Koch's essay records a motivation quite different from scientific argumentation. A few years ago, while sitting alone on a beach, he experienced the boundary between self and world dissolve. He describes this as "the most meaningful experience of my life," and, drawing on Aldous Huxley's concept of "Mind-at-Large" from The Doors of Perception, writes that the experience "flipped my view of reality."
Koch does not present this experience as empirical evidence. In his interview with ScienceAlert, he acknowledged that subjective experience does not constitute empirical proof, but explained that it gave him "a glimpse of Mind-at-Large" and served as a motivation to reexamine his assumptions about consciousness. His claim as a scientist is directed not at the content of the experience itself, but at the fragility of the assumptions that such an experience exposes.
The Path to Testable Hypotheses Remains Unpaved
The most legitimate criticism of Koch's proposal is likely its lack of falsifiability. Idealism is a metaphysical framework, and as such cannot itself be confirmed or refuted through experiment. Koch anticipates this criticism himself. At the end of his essay, he writes: "The most important task for the future is to take these insights and translate them into empirically testable hypotheses."
IIT's is, in principle, a measurable quantity that could serve as an objective indicator of the presence or degree of consciousness. In fact, Koch's research team has been involved in developing methods to detect consciousness in as many as 20% of unresponsive patients who may actually retain awareness. This method—delivering a brief pulse to the brain and measuring the complexity of its electrical response—is one practical application consistent with IIT's predictions.
However, there remains an unbridged logical gap between serving as a measure of the "amount" of consciousness and consciousness being a fundamental property of reality. IIT can serve as a tool for predicting which systems possess consciousness, but it does not directly answer the ontological question of why consciousness exists at all.
Moreover, this essay remains unpublished and has not undergone peer review. It has been made public only through the symposium presentation and its provision to ScienceAlert, and has not yet passed through the academic verification process. It would be more accurate to say that Koch's claim is not at a stage of "overturning established theory," but rather at a stage of "planting the seeds of debate to reexamine the premises of established theory."
Thirty years have passed since Chalmers coined the term "hard problem" in 1995. The data accumulated since then is vast, but it may not have brought us one step closer to the core question: why does experience exist at all? What Koch's proposal suggests is not that the answer cannot be found, but that the very framing of the question may be wrong. Whether that possibility can be tested by scientific methods will determine whether this effort succeeds.