In 1995, philosopher David Chalmers named what he called the "hard problem" of consciousness: why is there something it is like to be you? Not just information processing, subjective experience. Why does it feel like anything at all?
Thirty years later, neuroscience still has no answer. The explanatory gap Levine identified in 1983 is still a gap. We can map which regions light up during a given experience, but we can't explain the step from electrochemical activity to the redness of red or the grief of loss. The standard materialist position requires consciousness to emerge from matter that is itself entirely unconscious, and no serious theory has shown how that jump happens.
The quick rebuttal to any non-materialist view of consciousness goes like this: damage the brain and you change the mind, therefore the brain produces the mind. Anesthesia eliminates experience. A stroke can erase language. Alcohol alters judgment. Brain, mind, done.
But as philosopher Paul Marshall has pointed out, dependence is not the same as production. A prism depends on the light that passes through it. Damage the prism and you lose the rainbow. That doesn't mean the prism created the light.
This is the core move of what's called the filter or transmission theory. The brain, in this framing, does not produce consciousness. It constrains, selects, and transmits a consciousness that exists independently. The operative words, as Marshall puts it, are "filter, transmit, permit, channel, select, extract, limit, regulate, condition, modify. Not produce, generate or create."
William James made this argument in his 1898 Ingersoll Lecture, Human Immortality. His exact framing: "When we think of the law that thought is a function of the brain, we are not required to think of productive function only; we are entitled also to consider permissive or transmissive function." He used the analogy of a prism refracting white light. The prism reveals colors it did not make. James called the pre-existing field the "mother-sea." Carl Jung and Wolfgang Pauli later called it unus mundus.
Henri Bergson, writing in Matter and Memory in 1896, pushed further. For Bergson the brain's primary job is eliminative. It filters out most of consciousness, leaving only what's relevant to immediate action. Memory, on this view, isn't stored in neurons. The brain selects which memories to surface. The rest isn't erased; access is blocked.
The filter theory needs somewhere for that pre-existing consciousness to live. Panpsychism provides the answer. In its broadest form, panpsychism holds that consciousness is a fundamental property of matter, existing essentially everywhere, rather than something that appears only when neurons arrange themselves correctly. Philosopher Galen Strawson defines it as "the view that the basic physical constituents of the universe have mental, and in particular experiential, properties."
This isn't a new fringe position. Plato took it seriously. William James and Bertrand Russell both engaged with it directly. The view that consciousness is fundamental, like mass or electrical charge, has a long pedigree.
A more recent version, cosmopsychism, extends the claim: the universe itself is conscious, and individual minds are filtered expressions of that whole. Philosopher Paul Draper's related "psychological ether theory" proposes that brains don't produce consciousness but make use of it. Consciousness was already present before brains evolved, like an all-pervasive medium.
In November 2025, this framing got formal mathematical treatment. Maria Strømme, Professor of Materials Science at Uppsala University, published a paper in AIP Advances. Selected as best paper of the issue. Proposing that consciousness is not an emergent property of neural processes but a foundational aspect of reality. Drawing on quantum field theory and non-dual philosophy, her framework models universal consciousness as a fundamental field from which space, time, and matter arise. As she put it: "consciousness is not viewed as a byproduct of brain activity, but as a fundamental field underlying everything we experience. Matter, space, time, and life itself."
Roger Penrose and Stuart Hameroff's Orchestrated Objective Reduction (Orch OR) theory sits at an interesting midpoint. It anchors consciousness in quantum state reductions in brain microtubules while also proposing that primitive protoconscious events occur independently of the brain, embedded in spacetime geometry itself.
Philosophy and physics are one thing. Clinical observation is harder to dismiss.
Terminal lucidity refers to the sudden return of full awareness in patients whose brains have been severely and irreversibly damaged, often in the final hours before death. Alzheimer's patients who haven't recognized family members in years suddenly converse lucidly. The brain tissue is not recovering. Something else is happening.
A 2025 paper in International Psychogeriatrics stated it plainly: terminal lucidity "presents a significant challenge to physicalist assumptions that strictly associate cognitive function with brain integrity. The sudden return of awareness in individuals with profound and irreversible brain damage raises the possibility that consciousness, at least in some instances, could operate independently of the brain." A pilot study found that 73% of interviewed healthcare professionals had personally witnessed at least one such event.
If the brain stores memories and generates awareness, a destroyed brain should produce neither. The filter model predicts exactly what we observe: a failing filter briefly loosens its grip, and the signal comes through clearly one last time. NYU Langone's Parnia Lab is currently running a prospective study monitoring dementia patients at end-of-life with continuous video EEG. Their working hypothesis captures it well: "The information remains; access is blocked."
Near-death experiences follow a similar logic. A 2025 paper in the International Review of Psychiatry noted that NDEs appear to occur at the precise moment in cardiac arrest when brain electrical activity is absent or severely disturbed. A production model struggles with this. A filter model doesn't.
In April 2026, neuroscientist Christof Koch addressed these challenges directly at the 15th "Behind and Beyond the Brain" Symposium, arguing that phenomena like near-death experiences and terminal lucidity may require revisiting panpsychism and idealism as serious frameworks. Theoretical neuroscientist Àlex Gómez-Marín made a similar argument publicly in May 2026, tracing the history from Galileo forward and calling for a science that takes inner experience seriously rather than setting it aside as unmeasurable.
None of this means neuroscience is wrong about its correlational findings. Brain damage does alter experience. Drugs do change consciousness. These facts are solid. The question is what they mean.
If the brain is a filter rather than a generator, then everything neuroscience has mapped describes the filter's mechanics, not the origin of what's being filtered. Understanding the prism is still worth doing. The structure of the prism determines what gets through. But studying only the prism and concluding there's no light source behind it is a category error.
The hard problem persists precisely because we keep looking for consciousness inside the thing that processes it. Charles Murray, in a 2025 Wall Street Journal exchange with Steven Pinker, compared materialism's current position to "Newtonian physics in 1887". Apparently settled, but about to collide with phenomena it can't accommodate.
That analogy might be premature, or it might be exactly right. What's clear is that the filter hypothesis has been scientifically and philosophically serious since 1898, and the empirical pressure on strict materialism has only increased since then.