Open the map

Head to head

Descartes’s Substance Dualism vs Orch OR

Descartes’s Substance Dualism and Penrose-Hameroff’s Orchestrated Objective Reduction, compared field by field from their entries in the Atlas.

At a glance

Add more theories to this comparisonCompare other theories

Dualism Descartes’s Substance Dualism René Descartes
Quantum & Dimensions Penrose-Hameroff’s Orchestrated Objective Reduction Roger Penrose, Stuart Hameroff

The claim

In brief
Descartes’s Substance DualismRené Descartes holds that consciousness, which he calls thought (cogitatio), is the essence of an immaterial thinking substance (res cogitans) wholly distinct from extended, mechanical body (res extensa). Every conscious state, from reasoning and willing to pain, color, and emotion, is a mode of the thinking thing and is immediately present to it. Sensations and passions, though, arise only in the union of mind and body, where brain processes stand in regular relations to experiences they do not resemble.
Orch ORThis theory posits that consciousness arises from non-computational, gravitation-mediated objective reduction (OR) of quantum superpositions occurring within the protein structures (microtubules) inside brain neurons. This process, termed Orchestrated Objective Reduction (Orch OR), bridges the gap between quantum mechanics and classical reality to produce phenomenal experience.
What consciousness is
Descartes’s Substance DualismConsciousness is thought, defined as everything that happens within us insofar as we are immediately conscious of it, and it is the principal attribute of the mind.
Orch ORConsciousness is identified as a non-computational physical process—the specific orchestration of gravitation-mediated objective reduction of quantum states linked to the fine-scale structure of spacetime geometry. Proto-conscious moments are fundamental and ubiquitous in the universe.

Big questions

Can AI be conscious?Both agree
Descartes’s Substance DualismNoSince thought belongs only to immaterial substance and matter is pure extension, a machine, however complex, would be mechanism without a mind.
Orch ORNoConsciousness is fundamentally non-computational and relies on specific biological quantum processes (Orch OR in microtubules); digital simulation cannot replicate true sentience.
Does consciousness survive death?Differ
Descartes’s Substance DualismYesDescartes presented the real distinction of soul and body as what makes the soul’s survival intelligible, and the Meditations announce that aim in their subtitle.
Orch ORPossibleAs a non-local quantum process in spacetime geometry, consciousness provides a potentially plausible mechanism for phenomena like near-death experiences, the afterlife, and reincarnation.
Could a mind be uploaded?Differ
Descartes’s Substance DualismNoCopying the body’s mechanism would not copy the immaterial thinking substance.
Orch ORConditionalMind uploading requires recreating consciousness in an artificial medium (e.g., carbon nanotubes) that possesses the necessary quantum physical properties to sustain and orchestrate objective reduction events.
Does it give life meaning?Both agree
Descartes’s Substance DualismCosmic/UltimateDescartes’s system rests on a non-deceiving God who guarantees knowledge and created even the eternal truths.
Orch ORCosmic/UltimateProto-conscious moments are fundamental and ubiquitous, linking consciousness to the fine-scale structure of reality, suggesting inherent cosmic relevance and possibly enabling evolution itself.

Nature of mind

Ontology
Descartes’s Substance DualismSubstance dualism (Cartesian)
Orch ORQuantum Theory (Non-computational Physicalism / Proto-panpsychism)
Mind and body
Descartes’s Substance DualismMind and body are really distinct finite substances with exclusive essences, thought and extension, and could by divine power exist apart. They are joined in the human being, where bodily motions give rise to sensations and the mind moves the body, though Descartes never explained that interaction satisfactorily.
Orch ORConsciousness is non-computational physics. The brain's microtubules act as a mechanism to orchestrate proto-conscious quantum activity into coherent, rich conscious experiences, requiring a physics beyond current understanding.
Fundamental or emergent
Descartes’s Substance DualismPrimitive
Orch OREmergent/Primitive (Hybrid)
Qualia
Descartes’s Substance DualismSensory qualities are not properties of matter, which has only size, shape, motion, and arrangement. Experienced redness or pain is a mental mode arising in the embodied union and cannot be captured by extension.
Orch ORRich conscious experience (qualia) arises when orchestrated objective reduction occurs in neuronal microtubules, connecting the quantum information processing to the fundamental structure of spacetime geometry.

How it works

Mechanism
Descartes’s Substance DualismMechanism on the bodily side and non-reduction on the mental side. Light mechanically affects eyes, nerves, and brain, and the mind then experiences color, distance, and shape in regular correspondence with those motions.
Orch OROrchestrated Objective Reduction (Orch OR), where non-computational, instantaneous quantum state collapse is leveraged by coherent quantum activity sustained within microtubule lattices.
Where it is
Descartes’s Substance DualismThe mind is unextended. Sensations and passions are felt as belonging to one’s own body, and Descartes located mind-brain communication in the pineal gland.
Orch ORLocalized within neuronal microtubules, particularly in the brain, but fundamentally drawing upon ubiquitous proto-conscious properties throughout the universe.
What it does
Descartes’s Substance DualismPassions are caused and strengthened by movements of the animal spirits and dispose the soul toward volition and action. The will can in turn move the body.
Orch ORConsciousness provides real-time conscious causal action through non-computable objective reduction events, potentially linked to the fundamental mechanisms of free will and choice.

Evidence and criticism

Testability
Descartes’s Substance DualismConceptually testable
Orch ORTheoretically testable; versions involving collapse dynamics can, in principle, be tested with quantum computers, though current tests are rudimentary.
Tests so far
Descartes’s Substance DualismNot stated
Orch ORStudies showing that general anesthetics, psychedelics, and antidepressants interact with microtubules.,Experiments aimed at testing quantum coherence maintenance in biological systems (e.g., tubulin studies).,Testing theoretical versions by combining IIT and collapse dynamics.
Criticisms
Descartes’s Substance DualismPrincess Elisabeth of Bohemia asked how an immaterial soul could move a material body, and the interaction problem remains unresolved. Arnauld and later critics charged circularity, since the proofs of God that guarantee clear and distinct perception themselves rely on clear and distinct perception. The standard reading denies consciousness to animals, which most now find implausible.
Orch ORThe main tension is the challenge of maintaining quantum coherence for biological timescales in the hot, wet environment of the brain (environmental decoherence). The theory also requires non-existent physics (quantum gravity).

Sources

Key sources
Descartes’s Substance Dualism
  • Meditations on First Philosophy, René Descartes (trans. J. Cottingham, R. Stoothoff, and D. Murdoch) (1984)
  • Principles of Philosophy, René Descartes (trans. J. Cottingham, R. Stoothoff, and D. Murdoch) (1985)
  • The Passions of the Soul, René Descartes (trans. J. Cottingham, R. Stoothoff, and D. Murdoch) (1985)
Orch OR
  • Shadows of the Mind: A Search for the Missing Science of Consciousness, Roger Penrose (1996)
  • Conscious., Microtub. ‘Orch OR’, Stuart Hameroff (2014)
  • Consciousness & new physics, Roger Penrose (2023)

More comparisons

Descartes’s Substance Dualism vs …

Orch OR vs …

All head-to-head comparisons →