substance dualism key term

substance dualism

the theory of mind that states that there are only two kinds of substances: mind and matter

leibniz’s law of indiscernibility of identicals

if two objects are in fact one and the same they have all the same properties

e.g. if bruce wayne and batman are the same person then they share all the same properties

descartes’ indivisibility argument

p1. physical substance is divisible

p1. the mind is indivisible

p3. identical things must have the same properties (in accordance with leibniz’s law)

c. the mind therefore cannot be identical with any physical substance, such as the body

descrates’ conceivability argument

the separability of two identical things is not even conceivable

e.g. we cannot conceive of a triangle without three edges and three vetices

since we can conceive of the mind without the body it follows that it is possible for the mind to be separate from the body, from which it follows the mind is actually not identical to the body

the conceptual interaction problem

p1. physical things can only move if they’re pushed

p2. only something that is extended and can touch the thing that is moved, can exert pushing force

p3. the mind has no extension

c. the mind cannot move the body