If Sam is a boy and Flo is a girl, Sam cannot be Flo and vice versa, but if all was true of Sam was true of Flo, they must be the same person.
N.B. the properties which identical objects share must include spacio-temporal location (where they are in time and space). If two identical objects are in different places but have all the same properties they are only
QUALITATIVELY IDENTICAL, if one thing is qualitatively identical with another thing, then it exactly resembles that other thing. If one is destroyed the other still exists.
They are not NUMERICALLY IDENTICAL, if one thing is numerically identical with another thing, then we really only have one thing. If one is destroyed, simultaneously so is the other.
The simplest argument for dualism is based on these principles of identity, the argument starts by looking at the properties of mind and matter (including our physical bodies).
When considering the properties of matter, we can count the fact that matter exists in definite moments of time and space. So, you can always say where and when a bit of matter is.
Another feature of matter is that it is observable by all; PUBLIC (you can even see the smallest particles under a microscope).
And FINALLY, matter is always DIVISIBLE.
When considering the properties of mind, we find it doesn’t fit the same description. If I think ‘where is Kate?’ that thought cannot be located in time and space in the same way an object/particle can (matter). It doesn’t make any sense to say my thought occurred three inches behind my nose.
ALSO, minds are not observable by any one (PRIVATE)...feelings, thoughts and sensations cannot be seen by ‘looking into my mind’.
And our mind seems to be INDIVISIBLE; my consciousness cannot be split up into infinitely small parts.
Minds seem to have a feature which matter doesn’t. I can be in error about matter, about the external world...BUT I cannot be in error about the state of my mind. (If I think I saw a canary, I could be mistaken that there is a canary.
THIS TABLE WILL MAKE THE DIFFERENCE BETWEEN THE PROPERTIES OF MIND AND MATTER CLEARER.
With this set of differences we can set out an argument using Leibniz’s Law:
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If mind is identical to matter, then mind must have all the same properties as matter.
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Mind has different properties to matter
- Therefore, mind is not identical to matter.
WHAT THEN IS THE MIND!!?!???!?!?!
Given that matter is a kind of substance, it seems natural to think that mind must be some other kind of substance. THIS IS DUALISM. There are two types of substance in the world: mind and matter.
Good things about Dualism:
1. It fits in with our intuitive views about the mind.
2. The argument for it is straightforward.
ARGUMENTS AGAINST DUALISM (OBJECTIONS)
One major problem is interaction-how does the mind affect/interact with matter? We have an idea how matter affects matter they are the same substance.
But how can the mind interact with matter if they are fundamentally different types of thing? If the mind is not in space, how can it be affected by something that is in space?
WE KNOW THAT MIND AND MATTER DO INTERACT (MIND AND BODY). My arm moves when I when I want it too etc.
Reply: if the argument for dualism is good and interaction is a fact, it must be true that mind and matter can interact. Just because we don’t understand how they interact, doesn’t mean dualism is wrong.
