While bumping my way around the internet, a found an online excerpt from a book by a philosopher named Hilary Putnam. It attempts to show that the brain in a vat thought experiment is self–refuting, and implicitly disproves the real world. I am posting about it, not because I agree with it, but because I think it is interesting.
The argument starts by considering what a brain in a vat is. We can all imagine it, an evil mad scientist kidnaps us, cuts open our heads, puts our brains in a tub of fluid, and hooks them up to a supercomputer. The supercomputer feeds our brains with impulses, and it creates a complete illusion of reality. In principle, this means that nothing is “real” as there is no way for the brain to tell where it is.
Now, consider the case of a brain “born” in a vat. In such a case it would never experience anything of the “real” world, but rather only the supercomputer’s virtual world.
Suppose that the brain in a vat has a certain object in its world. Having a term for that certain object is a reasonable assumption, as it fulfills a need to talk about and think about that certain object. Let’s say that that certain object is called a flig. When the BIV refers to a flig, it is clearly referring to a virtual object, even if by coincidence a flig looks exactly like a brain in the real world.
Based on the previous, a BIV can only think about and talk about virtual things that have been fed to it by the supercomputer. This stays the same even if the word ‘flig’ is changed to ‘brain.’ Hence, if a brain in a vat in the real word says, “I am a brain in a vat,” what it is really saying is “I am a virtual brain in a virtual vat,” even though it clearly isn’t. Since the BIV is always stating a falsehood, the thought experiment is self-refuting. Basically, if all you know are virtual things and virtual facts, you cannot know anything about real things and real facts.
Recall that we are brains born in bodies. The role of our bodies and senses are hence directly analogous to the vat and the supercomputer respectively. We are therefore only thinking about things sent to us by our senses and not “real” things. Hence, if you say “I am a brain in a body,” what you are really saying is that “I am a virtual brain in a virtual body.” In this sense, nothing you see, think about, or experience, is real; the “real world” is all in your head.
Image via the Wikimedia Commons.