Hobbes vs Descartes
The Third Objections to the Meditations
Venue: The Third Objections (with Descartes's Replies) to the *Meditations*, in the 1641 first edition.
A young Cartesian system meets an established materialist sceptic.
When Descartes published the *Meditations* (1641), he solicited objections from leading intellectuals and printed them with his replies. The Third Objections, by Thomas Hobbes, are the sharpest of the set: Hobbes's sustained materialist-empiricist challenge to Descartes's dualist rationalism. Hobbes denied that we have a clear and distinct idea of the soul as immaterial; argued that the cogito proves only the existence of thinking but not of a thinking thing distinct from the body; rejected the doctrine of innate ideas; and questioned Descartes's theological-methodological apparatus. Descartes's replies are terse and often dismissive — he considered Hobbes's objections to misread his arguments. The exchange is the cleanest direct confrontation between Cartesian rationalist dualism and Hobbesian materialist empiricism in their founders' own voices.
Historical Context
Hobbes was 53, in self-imposed exile in Paris (where Descartes also lived); Descartes was 45, recently moved to the Dutch Republic. They had been in indirect correspondence through Mersenne, who organised the Objections. Their personal antipathy is well documented.
Parties
The cogito proves only that thinking occurs, not that there is a thinking substance distinct from the body. We have no clear idea of an immaterial soul; "soul" or "spirit" are words without referents in our experience. Cartesian dualism rests on confused appeals to clarity and distinctness.
Key arguments
- The cogito: "I think" presupposes thinking; it does not establish a thinker distinct from the thinking process or from the body that does it.
- No idea of immaterial substance: I have ideas of bodies and of their motions; I have no idea of an immaterial soul corresponding to clear-and-distinct introspection.
- Innate ideas: ideas are products of sensation and memory; the doctrine of innate ideas is unsupported.
- Theology: Descartes's ontological argument depends on conflating logical possibility with real possibility.
Allied schools
The cogito establishes the existence of a thinking thing whose essence is to think, distinct from any extended body. The clear and distinct idea of mind as immaterial substance is what introspection delivers; Hobbes's materialist scepticism rests on his refusal to introspect carefully.
Key arguments
- The cogito as cogito-ergo-sum: "I think therefore I am" establishes the existence of an *I* whose nature is to think, not merely the bare fact of thinking.
- Clear and distinct idea of mind: methodical doubt strips away everything but the thinking *I*; what remains is an immaterial substance.
- Innate ideas: mathematical and metaphysical truths are not derivable from sense alone; the doctrine of innate ideas is required.
- Hobbes's materialism conflates the body with the mind on the basis of insufficient introspective discipline.
Allied schools
Dimensions Engaged
Observer
Observer · Physicality: is the thinking self immaterial substance (Descartes) or material thinking-process (Hobbes)?
Matter
Matter · Ontological Status: is matter the only substance (Hobbes) or one of two distinct substances along with mind (Descartes)?
Verdict in retrospect
Neither side persuaded the other or, much, their immediate successors. Cartesian dualism dominated 17th-18th century philosophy of mind in continental Europe; Hobbesian materialism shaped the British empiricist and Enlightenment naturalist traditions. Modern philosophy of mind is broadly post-dualist (most working philosophers reject strong substance dualism), but the Hobbesian alternative is far from straightforwardly victorious — debates over consciousness, intentionality, and personal identity continue to engage Cartesian themes (Mary's Room, the zombie argument). Neither founder's position is dominant; their disagreement remains structurally fertile.
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Further reading
- Descartes, *Meditations on First Philosophy with Selections from the Objections and Replies* (tr. Cottingham, 1996), Third Objections
- Sorell, *Hobbes* (1986)
- Tuck, *Hobbes: A Very Short Introduction* (2002), ch. on the Objections