Presentation
What is the Leibniz’s Law used to defend Descartes’ argument for dualism and what is Sober’s criticism against Descartes?
Madison, Octavia, Mohemmed
Leibniz’s Law
Idea that if m and b are identical, then they must have all the same properties
Principle of the indiscernibility of identicals
If even one property of m is different than b then they are distinct entities
M has property P.
B does not have property P.
If m has a property that b lacks, then m is NOT equal to b.
https://www.youtube.com/watch?v=TvxnQRzZYYs
Applied to Descartes- Indubitable Existence Argument
Descartes claims you can’t doubt that you have a mind
Sober agrees with Descartes but
Existence of the body however is indubitable
Disembodied spirit
Mind has a property your body lacks
Sobers Criticism
Clark Kent, Louis Lane, and Superman
Louis Lane wants to marry Superman
Louis Lane does not want to marry Clark Kent
Superman is not identical with Clark Kent
Just because Louis wants to marry one and not other does not mean Clark and Superman have different properties, they are still the identical
According to Leibniz Law they are different
Descartes also claims that you can doubt one of the two propositions
I have a brain
I have a mind
Sober says that it does not follow that his brain has different properties from his mind
Propositions are different but that doesn't’t show the brain and mind are different OBJECTS
Conclusion
According to Leibniz Law if two objects or propositions have different properties then they are not identical
According to Sober, objects can have different properties and still be identical
Clark Kent and Superman