The neurons sit in small neutrient baths, and when it is time for a new experience to be delivered, each person receives instructions for the timing of how they are to stimulate their neuron. At the appropriate moment, each person delivers the specified patterns of stimulation all over the world, and the neurons go through the same patterns of activity which they would have if they were actually in the man's brain when he was experiencing some pleasurable activity. It is still thought that by doing this they actually bring about the corresponding mental state.
Now it happens one day that just when a new experience-delivery is about to begin, one person finds that his neuron has died. He knows that this won't affect the overall experience, since neurons die all the time and we can't tell if there are a few more or less. But he is personally disappointed because he knows that he will not be able to play his own small part in delivering the happy experience.
Then he gets an idea. His own brain is full of neurons as well, firing
all the time. At the appropriate time, he moves the neural bath out of
the way and bends over and puts his own brain into the position where
"his" neuron is normally kept. Since his own brain is active, he is
sure to have a neuron fire which is in the right place and at the right
time for each of the stimulations he is supposed to give. In this way
he can participate in delivering the experience using the neurons in
his head rather than the one in the bath.
But then he thinks, why bend over? It doesn't matter where the neurons are located, all that matters is the pattern of their stimulation. And then he thinks, what about all the other people who are stimulating their own neurons? They have brains too, full of neurons just like his. Any time they were supposed to be stimulating their neuron in its bath, they had neurons in their head which were firing at exactly that moment. If all that is necessary to produce a conscious experience is to have neurons fire at the specified times and places, there is no need for anyone to stimulate anything. Just by standing there, their own brains provide more than enough neural firings to produce any neural pattern (and therefore any mental experience) imaginable.
It would seem to follow, then, that the entire enterprise has been a folly. Either all possible mental states are existing all the time just due to random neural firings in disconnected brains all over the world, or else these carefully planned stimulations, which were designed to mimic actual neural patterns in a conscious brain, were not actually producing any mental states.
So, what do you think? Were they producing mental states by stimulating those neurons? And if so, are they still produced when they just stand their and let their brains do the work of firing neurons?
Hal