Step 1: Recall Descartes’ mind-body dualism.
In Descartes’ philosophy, mind and body are two distinct substances:
Mind (res cogitans) = thinking substance.
Body (res extensa) = extended substance.
Step 2: Evaluate option (A).
(A) Correct: Descartes holds that mind and body are two different kinds of substances, which is precisely substance dualism.
Step 3: Evaluate option (B).
(B) Correct: Descartes defines the essence of mind as thinking. Even if one doubts everything else, the act of thinking remains certain.
Step 4: Reject option (C).
(C) Incorrect: For Descartes, the essential property of matter is extension (being spatially extended), not Aristotelian form. The idea that matter’s essence is determined by form belongs to Aristotelian/Scholastic metaphysics, which Descartes rejects.
Step 5: Reject option (D).
(D) Incorrect: Descartes claims the mind is indivisible (not made of parts), but the body is divisible because it is extended. Therefore, it is false that both are indivisible.
Step 6: Conclusion.
The correct statements consistent with Descartes’ dualism are (A) and (B).
Final Answer: (A), (B)