DESCARTES – Substance Dualism Descartes denies that he is a body. There are two kinds of substances; minds (thinking things) and bodies (extended things). Bodies are things in space that take up space; they have a shape and can move. A human body is an extended thing but so is a coffee cup. By a thinking thing, Descartes means a thing which is conscious; not necessarily something that reasons. No body is a mind and no mind is a body. If you’re accepting mind-body dualism, you’re denying naturalism. An essence is all the essential properties of a thing. An essential property is a defining property; one which a thing can’t exist without. ANTOINE ARNAULD - Objection It is one thing to know an essential feature of a thing but it is another thing to know all the essential features of a thing. Perhaps the mind/soul is not the only feature that is essential to a person. What if my body is also an essential property of mine? How can Descartes prove that being a thinking thing is all that is essential to be? You can know one essential property of an entity but you can also fail to realise that another thing is an essential property of that entity. Descarte’s argument is therefore not cogent. DESCARTES’ DIVISIBILITY ARGUMENT P1: Any mind is partless, and so it is indivisible. P2: Any body has parts, and so is divisible. Therefore for every extended thing, you can always separate its part. P3: Therefore no body is a mind and no mind is a body. Descartes is suggesting that humans seem to be simple. We are not aware of any parts of the self. Premise 2 is false if there are simple physical entities. For example, atoms.