Robert Lawrence Kuhn on the Landscape of Consciousness, Materialism, and Idealism

Robert Lawrence Kuhn built the most complete taxonomy of consciousness theories in existence — 444 entries and counting, sorted along a spectrum from pure materialism to pure idealism. He and Alex O’Connor tour the categories that spectrum contains, and the logic Kuhn used to draw the lines between them.

Key ideas

1. The taxonomy grew far past its brief. A journal editor asked Kuhn for an 8,000-word introduction to a special issue on quantum consciousness. He refused, relented after six months, and delivered a peer-reviewed paper of 175,000 words cataloguing roughly 225 theories. Panicked that it was still incomplete, he had the journal pull it from early online release for two weeks. The paper has since become an interactive site, Landscape of Consciousness (loc.closertotruth.com), whose map view was built by Alex Gómez-Marín and which now holds 444 theories — a figure that keeps growing as readers and the theorists themselves write in with corrections and additions.

2. His sorting test for materialism is procedural, not substantive. Kuhn defines a theory as materialist if nothing in it is, even in principle, permanently beyond the scientific method — ‘anything non-physical I define as something that’s not 100% subject to the scientific method.’ This is why nearly half of his 444 theories fall under materialism: a materialist theory can always in principle make scientific progress, whereas a non-physical theory cannot be pursued the same way, so materialist theories proliferate. It also explains a boundary problem he flags directly: Galen Strawson’s claim that ‘the real materialism is basically panpsychism’ only fails Kuhn’s test because proto-consciousness, on Strawson’s account, is not itself subject to scientific method — not because panpsychism is inherently non-physical.

3. Materialism itself splits into twelve subcategories. Kuhn’s materialist branch runs from philosophical theories (emergence, identity theory, functionalism) through eliminative materialism and illusionism (spun off into its own subcategory on David Chalmers’s advice), neurobiological theories (John Searle’s biological naturalism, Gerald Edelman’s neural Darwinism), electromagnetic field theories (Mostyn Jones, Tam Hunt, Jonathan Schooler, Earl Miller), computational functionalism (Hilary Putnam; Lenore, Manuel, and Avrim Blum), homeostatic and affective theories (Antonio Damasio’s emotion-as-generator view; Karl Friston’s free-energy and active inference), embodied and enactivist theories (Francisco Varela, Evan Thompson), relationalism and representationalism (Douglas Hofstadter’s strange loops), language-based theories, and phylogenetic/evolutionary theories.

4. Panpsychism and idealism differ on the ontological status of matter, not on whether consciousness is fundamental. Panpsychism keeps the physical world ‘equally real’ and adds proto-consciousness to it as a further ingredient present at every scale. Idealism makes the physical world either derivative of consciousness or illusory outright — Vedic and Hindu traditions take the illusion route; other idealists take consciousness to generate a physical world that is real but secondary. Cosmopsychism sits between the two: it locates the primary conscious subject at the scale of the whole universe rather than the electron, but — like panpsychism and unlike idealism — still grants the physical world equal ontological status. Panpsychism inherits the combination problem (how do micro-experiences combine into one mind); idealism inherits the mirror-image de-combination problem (how does one cosmic consciousness split into separate, non-overlapping individual minds).

5. Monism is its own category precisely because ‘everybody wants to be a monist.’ Kuhn restricts monism to theories built specifically around the claim that mind and matter are two expressions of one underlying stuff, rather than letting every reductive theory claim the label. Donald Davidson’s anomalous monism derives mental-physical identity from three premises that are jointly unsatisfiable unless the mental and physical turn out to be the same thing: mental events cause physical events; causation requires laws; there are no strict psychophysical laws. David Papineau’s radical identity theory makes the same move directly, comparing mental and physical descriptions to ‘the morning star’ and ‘the evening star’ — different names for the one planet, Venus.

6. The ‘Challenge’ category holds theories that reject Kuhn’s whole materialism-to-idealism spectrum as the right map. It runs from Colin McGinn’s mysterianism (the human brain evolved to survive on the savannah, not to solve the hard problem, and may be constitutionally unable to) through David Eagleman’s possibilianism and Paul Davies’s teleological account, on which the eventual emergence of consciousness retroactively selects which quantum histories occurred, via John Wheeler’s participatory universe. Kuhn’s sharpest illustration pairs two of his ‘intellectual heroes’ who land in Challenge for opposite reasons: Raymond Tallis, a committed atheist who rejects any reductionist account of consciousness as ‘neuromania,’ and Peter van Inwagen, a Christian analytic philosopher who is a materialist about the person and consciousness, and who resolves his belief in bodily resurrection separately from his theory of mind.

7. Quantum theories and integrated information theory (IIT) are separate top-level categories, each with an internal fight over where the theory actually bites. Under quantum theories, Roger Penrose and Stuart Hameroff locate consciousness in the collapse of a wave function inside neuronal microtubules, while Hartmut Neven’s rival account locates it in the wave function’s formation rather than its collapse. Under IIT — Giulio Tononi and Christof Koch’s theory, built around a measurable quantity of integration called Phi — Kuhn separates the empirically productive part (Phi’s real clinical use in assessing consciousness in coma patients) from the metaphysical part (the claim that a conscious experience just is a structure in a high-dimensional space), which he thinks earned IIT an unfair 2023 open letter from over a hundred researchers branding it pseudoscience, after an adversarial test against global workspace theory drew outsized media attention.

Context

Kuhn keeps his own view almost entirely out of the published survey — 72 words out of 175,000 — so as not to colour any theory he is presenting. Pressed by O’Connor, he describes leaning toward ‘some kind of dualism’ — a non-physical component to consciousness — with quantum theories as his fallback and illusionism or neurobiological materialism as a further fallback. He puts his own confidence in some form of non-physicalism at roughly 60–65%, a figure he says shifted a few points toward materialism after watching his daughter conceive and carry a healthy child from a mosaic embryo frozen for over a decade — an emotional reaction, he stresses, structurally no different from the near-death or psychedelic experiences that push other researchers the opposite way. He gives psychedelic and near-death experiences no ontological weight of their own, though he says his confidence on that point has softened.

Related

• Robert Lawrence Kuhn — guest; creator of Closer to Truth and the Landscape of Consciousness survey
• Alex O'Connor — host; Within Reason / CosmicSkeptic
• Consciousness — the wiki’s existing map of positions; this episode supplies the categories that map does not cover
• Panpsychism — the position Kuhn distinguishes from idealism and cosmopsychism throughout
• Materialism — the category Kuhn’s twelve subcategories sit under
• Illusionism — the subcategory Kuhn credits to Chalmers’s suggestion
• The Materialism Debate — theme this episode’s materialism/physicalism distinction speaks to
• Galen Strawson on Panpsychism, Physicalism, and Why Consciousness Is Foundational — Strawson’s ‘real materialism is basically panpsychism’ claim, discussed directly by Kuhn
• Keith Frankish on Illusionism, Consciousness, and the Hard Problem — the illusionism subcategory Kuhn describes carving out of eliminative materialism
• Anil Seth on Consciousness, Machine Sentience, and Why Intelligence Isn't Awareness — Seth is named by O’Connor among those who heard Alex Gómez-Marín’s talk on the map