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Is your brain in a vat?

Monday, February 25, 2008 - 11:45 AM

The 'brain in a vat' thought experiment reminds us of issues we wrestled with in a past episode . What is the connection between brain and body? If your brain was placed in a jar and wired to a computer that simulates the outside world, how could you prove that your beliefs about the world aren't all false?

 

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Comments [5]

Carlo

I think the Matrix was loosely based on the Brain in a Vat theory. I wonder if all the people who loved that movie for its "original" story have even heard of this theory, let alone read Descartes...

Feb. 27 2008 02:09 AM
Shaun

Would the mind die physically if it thought that it actually died? I understand, thanks to RadioLab and their wonderful piece on Placebos, that the mind is capable of simulating plenty of situations that can heal but I wonder if it can hurt itself equally as well through thought alone? If it could, how would the physical structure itself change to reflect what the simulated world told the person?

If you could hurt yourself and change shows up on your brain, then it would be possible to think about suicide with enough willpower behind it and you would eventually keel over. I don't know if there have ever been any recorded cases of suicide by thought yet but if there have, that could lend evidence to the idea that we are brains in a jar.

If you couldn't hurt yourself through thought alone, then putting a shotgun in your mouth would simply cause your brain to think it was dead but you would eventually come out of it, such as the placebo effect demonstrated by showing the decreased recovery rates. Your brain therefore wouldn't be able to actually die but just emulate something like it.

The physicality is where the truth lies.

Feb. 26 2008 02:45 PM
mike

I find that taking the solipistic stand point (as ironic as that sounds) is fun when you encounter those street preachers (of all religious stripes). It turns the tables. I actually had one such preacher looking at his watch and claiming he had "somewhere he needed to be" to get out of the discussion.

SOOOOO much fun.

Feb. 26 2008 01:45 AM
Colin

This is the problem that Descartes faces in Discourse on Method, except that he characterizes it as a demon feeding him false sensory information. His solution to the problem is a bit of a finesse - having proven (in his mind) the existence of God, he reasons that God would not permit such a thing.

I don't think there is any way to prove that you're not a brain in a vat connected to a powerful computer. You can't prove it a priori, and any attempt to prove it a posteriori would be circular, because you'd need to use evidence and reasoning drawn from the world around you, which could be generated by the computer and thus falsified. At any rate, your philosophical opponent can always assume that the computer is ridiculously powerful and can emulate just about anything.

However, I have heard it said that it might be possible to demonstrate that you're not an isolated mind that is merely hallucinating the world around you, such as that described in Mark Twain's The Mysterious Stranger. One approach would be to carry at all times a book of limericks that you haven't finished. When a spasm of existentialist doubt strikes you, simply open the book to the next limerick you haven't read - the idea being that it would be impossible to spontaneously create a quality limerick.

Feb. 25 2008 10:21 PM
Rich Meitin

I'm not sure how I could prove my beliefs about the world aren't all false even if I'm NOT a brain in a vat!

For one thing, our beliefs are constrained by our senses. We see only about an octave of E.M. energy (light), as I recall. We hear only a few octaves of sound. We taste only a few flavors on the tongue. Our best human perceptions can account for only a tiny slice of "reality." That's just one issue.

Feb. 25 2008 08:03 PM

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