Dualism
Descartes’s Substance Dualism
Consciousness as the Essence of a Thinking Substance
René 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.
René Descartes
What consciousness is
Consciousness 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.
Mind and body
Mind 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.
Mechanism
Mechanism 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.
Core claims
- Even if all sensory content is deceptive, the occurrence of doubting, willing, imagining, and sensing cannot be doubted while it happens.
- Mind and body have mutually exclusive essences, thought and extension, so they are distinct substances.
- Sensations and passions are bodily in cause but mental in occurrence.
- Sensory qualities belong to the mind, not to matter, which Descartes reduces to size, shape, and motion.
Criticisms
Princess 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.
Implications
- AI consciousness: No
- Since thought belongs only to immaterial substance and matter is pure extension, a machine, however complex, would be mechanism without a mind.
- Survival beyond death: Yes
- Descartes 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.
- Meaning and purpose: Cosmic/Ultimate
- Descartes’s system rests on a non-deceiving God who guarantees knowledge and created even the eternal truths.
- Virtual immortality: No
- Copying the body’s mechanism would not copy the immaterial thinking substance.
Related theories
- Trialism (Extension)
- Malebranche’s Divine Occasionalism: Inner Sensation and Phenomenal Experience (Extension)
- Avicenna’s Flying Man and Self-Present Soul (Overlap)
- Swinburne's Substance Dualism (Extension)
Sources
- 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)
- Discourse on the Method and Dioptrics, René Descartes (trans. J. Cottingham, R. Stoothoff, and D. Murdoch) (1985)
- Descartes’s Dualism, M. Rozemond (1998)
- Descartes and the Meditations, G. Hatfield (2003)
- Cartesian Trialism, J. Cottingham (1985)