3 - Descartes Indivisibility Argument

Argument for substance dualism

what is substance dualism

the claim that both minds and bodies exist, so the mind is an ontologically distinct substance

in traditional dualism, what are the two types of substances that exist

mental and physical

what form of substance dualism is defended by Descartes, and what does it claim

cartesian dualism, minds are not dependent on bodies

what are the very different essential properties Descartes claims the mind and body have

thought and extension

how does descartes understand the minds essential property of thought

through consciousness and Intentionality

how does Descartes use the different properties he claims to show the mind and body are separate

if they were the same thing they would have the same properties

how did Liebniz later formalise Descartes claim

if two things are identical then they share all their properties because one thing cannot have different properties from itself

what did leibniz call his claim

the principle of indiscernibility of identicals

why can the mind not have extension, according to Descartes

it has no parts that can be divided - it is something single and complete

unlike the mind, what has extension (e.g. it can be divided into parts)

the body

what could be used as evidence that the mind does have parts and can be divided

mental illnesses such as multiple personality syndrome, theories of unconsciousness

how could descartes respond to the argument that the mind is dividible (e.g. via mental illnesses)

the kind of divisibility is completely different from physical division

could you possibly undermine the idea that physical objects are divisible

yes, atoms

as there are some physical things which aren’t divisible (e.g. force fields) what does this mean for the mind

that its indivisibility does not entail that it isn’t physical

what does Descartes assume in his argument

that the mind is a substance, just not a physical one

what instead could we claim the mind is

just mental properties, rather than a substance

are properties generally divisible (makes sense with our understanding of the mind)

no

what does Descartes need to show in order for his argument to work

that the mind is a substance