My philosophy professor brought this question up today as part of an exploration of Descartes' method of doubt, and since he conveniently replaced b.i.a.v. with Descartes' evil God, which in my reading comes about as the necessity to make pure systems falsifiable. By coming into existence only to invalidate such systems, e.g., math, he also by extension makes everything else not already discarded previously subject to the philosophy of math.

Because b.i.a.v. is a supersystematic explanation for an unverifiable construct in a lesser system, namely truth, it, by recourse to a greater system to explain an inconsistency in a lesser one, comes under the power of G because it is a greater system attempting to explain an inconsistency in a lesser one it itself cannot be both complete and consistent; therefore (if it is not a complete system) it cannot exist, or (if it is an inconsistent system) another system greater than that one must be called on to explain its own inherent inconsistencies, which itself must have its own inherent inconsistencies to be explained by an even greater system, itself inherently inconsistent, and so on and so forth ad infinitum.

This means that brains in a vat invokes infinity. By invoking infinity, brains in a vat--as with the Forms--by needing something to explain the explanation (what is the Form of the desk but the Forms of the parts of the desk, themsleves the Forms of the parts of the parts of the desk, until you have to have a Form for every single antineutron or green strange quark or graviton in the desk and then their constituent parts?), it explains jack squat. It violates Occam's Razor. Therefore, it inherently ought to be false.

The best objection I can make against the Brains in a Vat argument being metaphysically true is that our world lacks the discrepancies you would expect to find in a virtual reality -- that our world functions too much like a real world for it to be a simulated imagery, and that a Vat-world doesn't make sense: wouldn't the machinery operating the vat make errors or break down sometime? Even if we assume our memories can be modified after the fact so we don't remember such events, that process ought to suffer from the occasional error as well. Is the race of beings which developed the machinery infallible? Did the vats emerge from unguided natural processes? Neither option seems possible -- infallibility and complex machinery don't come from nothing -- the first isn't fully possible and the latter requires a process of trial and error not possible for unintelligent, natural processes.

Of course, you can switch out vats for another skeptical argument -- Descartes' evil demon for example -- but the general idea remains the same. Upon a closer inspection, skeptical worlds don't seem possible -- so much so that the real question ought to be whether it is possible for humans to know if it is possible for a skeptical world to exist. Can any advocate of the skeptical world demonstrate how it is possible for a skeptical world to possibly exist? And I would like to highlight the difference between the possibility of a skeptical world and the possibility of the possibility of a skeptical world:

The possibility of a skeptical world hinges on the capacity for a skeptical world being in existence -- it might not exist, and might never exist, but it could exist, somewhere in being, because being has such qualities that the existence of a skeptical is consistent with the algorithms underlying existence.

The possibility of the possibility of a skeptical world depends on the consistency of such a capacity with the algorithms underlying existence. If the capacity is inconsistant with those algorithms, then skeptical worlds are not possible.

I accidently took this up in Phil 101

Quote:
Originally Posted by TickTockMan
As for myself, I would think that the gap between appearance and reality could be bridged by logic/critical thinking.

The Matrix could indeed be used as an example here, in that it appears to portray reality, but in reality (the place where people like you and I have to be able to function), it's just a movie.

Also, The Matrix appears to be an original concept to some, when in reality it's just a flashy rehashing of the "brain in the vat" concept. Brain in a vat - Wikipedia, the free encyclopedia

I don't remember the first Matrix movie very well, but I seem to recall that people did not even quite achieve brain in a vat status, but only the status of a person in a bathtub stuck on a big wall of other people in bathtubs.
Moreover (and here I'm relying on several sessions of idle movie channel prowling in a dazed state trying to figure out which of the other Matrix movies was which while actually spending maybe a total of a half hour marveling at Monica Bellucci's ability to fill out her matrix-generated persona) people's very bathtub denizen status seems to have been imperiled....all of which made me wonder if there is anything consistant at all about the Matrix movies.

Why should it matter as long as the inhabitants of the Matrix believe it is all consistent?

They may think it is consistant, but since "the matrix" is from my point of view a jumble of movie scenes, I was hoping for some consistancy so I could impose some order on my cinematic experience.

A nice thought experiment, but anyone who really believes they are a brain in a vat is probably a little.....different.