Explain Descartes’ conceivability argument for substance dualism and Ryle’s objection that dualism makes a category mistake.
AQA A-Level Philosophy | Paper 2 | 2026 Predicted Paper | Question 9 Mark Scheme
Explain Descartes’ conceivability argument for substance dualism and Ryle’s objection that dualism makes a category mistake.
[12 marks]
What is expected
This is a 12-mark AO1 explanation question. Students need to give a detailed and logically organised account of both parts of the question: first, Descartes’ conceivability argument for substance dualism, then Ryle’s category-mistake objection to dualism. There is no requirement to decide whether Descartes or Ryle is ultimately correct.
For the highest marks, the two parts should be philosophically precise. In particular, students need to explain the move from conceivability to possibility and then to distinctness, rather than merely saying that Descartes can imagine a mind without a body.
Levels of response
Marks | Descriptor |
10–12 | A precise, detailed and logically organised explanation. Descartes’ argument and Ryle’s objection are both explained accurately and in sufficient depth. Philosophical terminology is used consistently and the response remains directly relevant. |
7–9 | A clear and generally detailed explanation of both parts. There may be a minor omission, imprecision or imbalance between Descartes and Ryle. |
4–6 | A broadly correct explanation containing relevant knowledge of both areas, but important stages of the reasoning may be missing or underdeveloped. |
1–3 | Some relevant knowledge is demonstrated, but the response is fragmentary, substantially incomplete or confused. |
0 | Nothing worthy of credit. |
Indicative content
Descartes’ conceivability argument
Students may explain that substance dualism claims that the mind is not identical to the body or any part of the body. The mind and body are distinct substances.
Descartes identifies different essential characteristics:
the essence of mind is thought, and mind is unextended
the essence of body is extension, and body does not essentially think
Descartes argues that he can clearly and distinctly conceive of the mind existing without the body. AQA's subject-specific vocabulary states that Descartes takes conceivability to entail possibility: because he can conceive of mind existing without body, it is possible for mind to exist without body.
The reasoning may therefore be reconstructed as:
Descartes can conceive of his mind existing without his body.
What can be conceived in this relevant clear and distinct way is possible.
Therefore, it is possible for the mind to exist without the body.
If mind and body were identical, it would not be possible for one to exist without the other.
Therefore, mind and body are not identical.
They are distinct substances.
Students may also express the point in terms of the essential properties of the two substances: mind is essentially thinking and unextended, whereas body is essentially extended and non-thinking. AQA describes the argument as a deductive argument from these different essential natures to their status as distinct substances.
The current specification presents this argument without reference to God, so students do not need to introduce Descartes’ theological guarantee of clear and distinct ideas.
Ryle’s category-mistake objection
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