6-45 Reject supervenience.
. . . is disputed by . . .
6-46 Rejecting supervenience is unacceptable.
The claim (Tim Maudlin, 1989)
Rejection of supervenience (the doctrine that identical physical
activity gives rise to identical conscious states) leads to the
unacceptable consequence that a "brain-o-scope" could
reveal identical neuronal activity (down to the last atom) associated
with 2 different mental states. It could even reveal that one
person is conscious whereas the other isn't.
Rejecting supervenience leads to the unacceptable consequence that a person whose "brain-o-scope" reveals identical neuronal activity (down to the last atom) might have two different mental states. (Perhaps one is even unconscious while the other conscious).
The Maudlin argument
Maudlin says, "Even if mental states supervene on more than
just the physical activity of a system, the crucial role of the
entirely isolated block remains inexplicable. And, in countenancing
the possibility of such effects, the computationalist would cut
himself off from the research tradition from which the tradition
grew. To see this, let us apply the point directly to brain activity...."
Maudling supports this with,"Let us suppose that some time in the future the electro-encephalograph is so perfected that it is capable of recording the firing of every single neuron in the brain. Suppose that researchers take two different surveys of a brain which match exactly: the very same neurons fire at exactly the same rate and in exactly the same pattern through a given period. They infer (as surely they should!) that the brain supported the same occurrent conscious state through the two periods. But the computationalist now must raise a doubt. Perhaps some synaptic connection has been severed in the interim. Not a synaptic connection of any of the neurons which actually fired during either period, or which was in any way involved in the activity recorded by the encephalograph. Still, such a change in connection will affect the counterfactuals true of the brain, and so can affect the subjective state of awareness. Indeed, the computationalist will have to maintain that perhaps the person in question was conscious through the first episode but no conscious at all through the second. I admit to a great degree of mystification about the connection between mind and body, but I see no reason to endorse such possibilities that directly contradict all that we do know about brain process and experience" (T. Maudlin, 1989, p. 426).
References
Maudlin, Tim. 1989. Computation and Consciousness. The Journal
of Philosophy, vol. LXXXVI, no. 8, p. 407-432.