The Atheist's Guide to Reality_ Enjoying Life Without Illusions - Alex Rosenberg [107]
The possibility of such an explanation shows why the argument from what it’s like to have a red experience cheats science of any chance to explain what it’s like. The argument demands that neuroscience tell us what it’s like to experience red or to experience the smell of garlic or to experience the feeling of being tickled. But it insists that to answer this question, it won’t help a bit to know all the effects, in the brain or the rest of the body, of experiencing red or garlic or the sensation of being tickled. Telling us everything about what else happens just because you have these experiences won’t help us understand the experiences themselves. The same goes for telling us what causes the experiences. Suppose we know everything about what events, processes, or changes in the body or the brain bring about these experiences. That won’t help us know what they are like either. Furthermore, figuring out what experiences are composed of, what they are made of, what their parts, components, constituents are, doesn’t help answer the question of what it’s like to have them either.
But then what will enable anyone to answer the question of what having subjective experience is like? Nothing. We have already ruled out all the possibilities for answering this question. The demand is that science explain what it’s like to experience red, but not tell us anything about its causes and effects or what it is made up of in the brain or anywhere else. This, in effect, ties the hands of science. The method that science uses to tell us about things—fermions, gravity, genes, neural circuits—is to identify their causes, their effects, and their composition—how they work. The challenge to neuroscience of explaining what it’s like to be a bat turns out to be the demand that it solve that mystery with its hands tied behind its back. It’s no surprise that science can’t solve a problem posed this way. After all, science isn’t magic (of course, magic isn’t magic either).
So, why suppose there is a problem lurking in Nagel’s question about what it’s like to be a bat? Pretty clearly, the problem is the result of taking introspection seriously. It’s the feeling introspection gives us that even after everything about the brain is known, there will still be something left unexplained. Why? Because introspection can’t conceive how causes, effects, and composition explain what experience is like. But there is no reason to allow introspection to guide us.
Nevertheless, Nagel’s argument is really cool. It’s the sort of puzzle any philosopher would give his soul to have invented, if he had a soul. There is another thought experiment that makes the same point as Nagel’s. But it shows much more clearly how these arguments cheat. This one goes back a long way, to the eighteenth-century physicist, mathematician, and philosopher Gottfried Leibniz. His theological beliefs made him particularly eager to find arguments against scientism just when it was beginning to pick up speed with Newton’s work.
In his most famous work, The Monadology, Leibniz tried to prove that “perception can’t be explained by mechanical principles, that is by shapes and motions, and thus that nothing that depends on perception can be explained in that way either.” Leibniz knew nothing of neuroscience, still less of the molecular biology of the synapse. But his argument was meant to work no matter what post-1700 science might tell us about physical processes on any scale. He says, “Imagine there were a machine whose structure produced thought, feeling, and perception.” Of