Thesis - Descartes - Real Distinction
Todman (Theo)
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Write-up2 (as at 22/07/2010 20:12:29): Descartes - Real Distinction

What is Descartes’s argument for the ‘real distinction’ between mind and body? Is it a good one?

In this essay3, I consider two suggestions in the literature for Descartes’s Real Distinction argument. The first, the Modal Argument, is expounded by "Wilson (Margaret) - Descartes". The second, which I will term the Two-Substance Argument, is scattered throughout Descartes’s oeuvre and is expounded by "Rozemond (Marleen) - The Real Distinction Argument". In addition, I consider some objections to Descartes, together with his replies.

The Modal Argument

The Modal Argument is best explained by the following text from the Sixth4 Meditation: How does this argument work? Using the above numbering, Descartes’s first major premise is (1) that anything that he clearly and distinctly understands can be brought about by God. So, if (2a) he can clearly and distinctly understand one thing apart from another, (2c) God can (by (1)) separate them. Descartes’s second major premise is that if (by 2(c)) two things can exist apart, then (2b) they are really distinct. Finally, he claims (6) that he can clearly understand mind separated from body (himself as thinking, but lacking the principal attribute of body, namely extension), and (7) vice versa, so satisfying (2a) for mind and body. Consequently, by (1), God can separate them, giving (2c), though (3) the manner whereby he does this is irrelevant. The fact that, as things stand, (5) Descartes’s mind and body are closely joined is irrelevant to the argument, which deals in conceptual possibilities. Thus, given (2a) and (2c), we have (2b), for mind and body, which are really distinct, giving (8) in which by “I” Descartes means, from (4), his mind.

The Two-Substance Argument

Rozemond summarises her version of the Real Distinction Argument on p.35. She rejects the Modal Argument, claiming that mind and body are really distinct not because they are conceptually separable but because they are different substances. Of course, Descartes agrees that mind and body are conceptually separable, thinking them actually separable in order to maintain the orthodox Catholic doctrine of the immortality of the soul. However, according to Rozemond, this separability is a consequence of the real distinctness, rather than the reason for it.

So, to prove: Descartes’s major premise is: Hence, Descartes needs to prove: To prove (c) we need: … Leibniz’s Law, and Proving (d) also requires (e), together with the Attribute Premise: ..and To prove (g) by modus ponens, Descartes needs: … and Finally, to prove (i) we need to know when one property is not a mode of another: Consequently, (i) follows from (j), taking phi as thought and psi as extension, given: Several premises weren’t justified in the course of the argument. We don’t have space to provide full justification, so a few animadversions will have to suffice.
Is the Real Distinction Argument a Good One?
Formal versus Real Distinction
Incomplete Knowledge
Residual Problems

In-Page Footnotes

Footnote 2: Footnote 3: Written in March 2004 as a pre-submission for my BA Finals

Footnote 4: CSM.II.54.
CSM.II = "Descartes (Rene), Cottingham (John), Stoothoff (Robert), Murdoch (Dugald) - The Philosophical Writings of Descartes Vol II".

Footnote 5: Principles Sections 60-62. CSM.I.213-4.
CSM.I = "Descartes (Rene), Cottingham (John), Stoothoff (Robert), Murdoch (Dugald) - The Philosophical Writings of Descartes Vol I".

Footnote 6: Section 60

Footnote 7: CSM.I.210.

Footnote 8: Rozemond discusses this issue on p.16, and quotes a letter of Descartes’s to Gibieuf (CSMK.202) in support.
CSMK = "Descartes (Rene), Cottingham (John), Stoothoff (Robert), Murdoch (Dugald), Kenny (Anthony) - The Philosophical Writings of Descartes Vol III - The Correspondence".

Footnote 9: CSM.II.72-3.

Footnote 10: Rules for the Direction of the Mind, CSM.I.45-6. Eg. “… we cannot conceive of a shape which is completely lacking in extension …”.

Footnote 11: First Replies, CSM.II.85-6.

Footnote 12: CSM.II.140-1.

Footnote 13: CSM.II.142.

Footnote 14: Fourth Replies. CSM.II.154-5.

Footnote 15: CSM.II.156.

Footnote 16: CSM.II.158-9.

Footnote 17: Explicitly at steps (1), (2a), (6) and (7).

Footnote 18: CSM.II.159

Footnote 19: CSM.II.37-8.

Footnote 20: CSM.II.43.

Footnote 21: CSM.II.156, as discussed above under Incomplete Knowledge .

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  1. Blue: Text by me; © Theo Todman, 2018

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