Posted by alexandra_k on February 1, 2005, at 2:02:15
In reply to Re: It always amuses me that... » smokeymadison, posted by alexandra_k on January 30, 2005, at 21:45:20
Why the Identity Theory Isn't True.
The Identity Theory is a theory of the relation between the mind and the body / brain. According to the Identity Theory mental states are brain states.
The Identity Theorist maintains that science has discovered that the mind is the brain the way that scientists discovered that water is H2O and that heat is mean kinetic energy.
In order for it to be possible that mental states are brain states there must be a perfect correlation between mental states and brain states. If mental state x is brain state y then everytime x happens y must happen, and everytime y happens x must happen too.
It follows from this that only beings with brains like ours can have mental states like ours. Something without a brain could not have mental states.
Lots of people don't like this. It seems to be possible in principle that we could discover silicon based martians or that we could develop AI (artificial intelligence) and that these things could have mentality despite lacking a brain.
Leibniz law says that for x and y to be the same thing they must share all the same properties (at any fixed moment in time). That is because a thing is always identical to itself. If we can discover a genuine property that x has that y lacks then x and y cannot be the same thing.
(The following is derived from my interpretation of Kripke) .
Mental states are essentially subjective. (they can only be observed by one. There is something that it is like to have a mental life 'from the inside').
Brain states are essentially objective. (which is why many people can observe them. That is what makes them a fit object for scientific investigation).So mental states and brain states have different essential properties. They are essentially different. Brain states may well be correlated with mental states in beings with brains, but there is no reason why something else couldn't support mentality.
This is especially the case if we consider that what is so very important about brains - what it is about them that supports mentality - is to do with their complex structure and organisation.
If we could capture that complex structure and organisation with a computer program, then would we have AI with genuine mentality?
poster:alexandra_k
thread:449954
URL: http://www.dr-bob.org/babble/write/20050118/msgs/450891.html