The Modal Argument is an argument that the mind must be a distinct thing from the brain. The idea is that identity is a necessary property, but the mind and brain could possibly be distinct, so they must not be identical.
NOTES
- physicalism- only physical things exist
- physical- describable/explainable by physics
- Types of physicalism
- ontological physicalism- everything that exists is physical
- psychological physicalism- the mind is physical
- Modal Argument
- A thing is necessarily identical to itself
- So, if the mind and brain are the same thing, then they are necessarily the same
- It's possible that the mind and brain not be the same
- So, the mind and the brain are not the same
- By (2), (3); (rule of modal logic)
- Arguments for premise (3) of the Modal Argument
- A1: Conceivability Argument
- What is conceivable is possible
- It's conceivable that we exist apart from our brains
- S1: dreams
- S2 (Descartes): brain in a vat/evil genius demon
- S3: NDEs
- So it's possible that our minds are separate from our brains
- A2 (Descartes): Essential Property Argument
- Everything has one essential property that makes it what it is
- O1 (existentialists): there are no essential properties, only existence
- R1: implausible
- O2: there is no reason there couldn't be more than one essential property
- O1 (existentialists): there are no essential properties, only existence
- For us, it is our thinking alone
- S1: methodological doubt
- In all those other examples, we can doubt whether our bodies exist or not
- We can't doubt whether the doubter exists
- So, this must be our essential property
- O3: we don't always think
- R1: our essential property is our capacity to think
- O1: psychological physicalists believe the mind's capacity to think is the brain
- R1: our essential property is our capacity to think
- S1: methodological doubt
- So, we can exist even if our bodies don't
- Everything has one essential property that makes it what it is
- A1: Conceivability Argument