brains in vats

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I'm bringing this up because it's come up on my course...

If we were just brains in vats of nutrients and all our experiences and perceptions were illusions fed to us by a super computer, matrix-style, then we wouldn't be able to talk about being a brain a vat. It's not something we would actually experience knowingly and therefore we wouldn't be able to refer to it intentionally, just as somebody who has never seen a tree and who makes the noise, "tree" one day cannot be referring to a tree. Assuming that if we exist we must be able to refer to things and have intentionality, we cannot be brains in vats.

Any problems with this argument?

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Well, perhaps we wouldn't be able to talk about being brains in vats, but we would be able to talk about anything the computer programmed us to perceive, including trees. I think Star Trek covered a lot of this territory. The real question is would the illusion be preferable to our reality?

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Re: brains in vats

agrote wrote:

Assuming that if we exist we must be able to refer to things and have intentionality, we cannot be brains in vats.

Any problems with this argument?

Yes. Your assumption that "we exist," your apparently deductive inference therefrom that we "must be able to refer to things and have intentionality," and your unsupported conclusion. Apart from that, no problems.

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Re: brains in vats
Being a brain in vats of nutrients is a form of existence. If we were programed to feel the same sensations we feel now, what would be the difference?
And why would those perceptions be illusions?
Stimulus create sensations, centered in the brain. If you fell heat, the sensation is the same, no matter the cause is. The illusion would be your conception of the world. You would have the mental image of a tree caused, not by a tree, but by a computer program. Again, the mental image is the same. It's your conception of an exterior tree that will be illusory.
I dont see any reason that would prevent those brains from conceiving an imaginary situation (that would be similar to their real situation). I can conceive things that I never experienced. You dont need to feel the sensation of being a brain in a nutrient, to imagine the situation of a brain in a nutrient.
We dont need to experience something to conveive it. Democrit never saw atoms but his atomic theory of the universe is not a meaningless noise.
If we were those brains in vats of nutrients we would exist - as brains in vats of nutrients - and, if those brains were stimulated in order to create the same sensations we feel in our life, we would feel and think exactly as we do now, being able to refer to things (the question of the existence of those things being here irrelevant).
I never experienced being a brain in a vat of nutrients and that doesn't prevent me for conceiving that situation and speak about it.

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Re: brains in vats

joefromchicago wrote:

agrote wrote:
Assuming that if we exist we must be able to refer to things and have intentionality, we cannot be brains in vats.

Any problems with this argument?

Yes. Your assumption that "we exist," your apparently deductive inference therefrom that we "must be able to refer to things and have intentionality," and your unsupported conclusion. Apart from that, no problems.

It's not my argument or my conclusion - it's Hilary Putnam's (I may have got it wrong - anyone who's familiar with it please correct me). But assuming that we do exist, and assuming that if we exist we must be able to refer to things and have intentionality, surely we can't exist as brains in vats?

val wrote:

Being a brain in vats of nutrients is a form of existence. If we were programed to feel the same sensations we feel now, what would be the difference?
And why would those perceptions be illusions?
Stimulus create sensations, centered in the brain. If you fell heat, the sensation is the same, no matter the cause is. The illusion would be your conception of the world. You would have the mental image of a tree caused, not by a tree, but by a computer program. Again, the mental image is the same. It's your conception of an exterior tree that will be illusory.

But when we say, "that tree is nice" we don't mean, "the image of a tree on my retina is nice," we mean that we believe that an object, which we believe exists in an external world, independent of whether we percieve it, is nice. If we were brains in vats, we would be wrong to believe that there really is a tree.

Are you sure that we can imagine things we have never experienced? Unicorns are not real, we can imagine them, but really they're just ponys with horns, and we've seen ponys and horns before.

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Re: brains in vats

agrote wrote:

It's not my argument or my conclusion - it's Hilary Putnam's (I may have got it wrong - anyone who's familiar with it please correct me). But assuming that we do exist, and assuming that if we exist we must be able to refer to things and have intentionality, surely we can't exist as brains in vats?

First: If one assumes that we exist, then that pretty much rules out the "brain in a vat" scenario. After all, if we exist, yet we are not aware of how we exist (either in the commonly accepted fashion or as disconnected brains in vats or in some other manner), then how can we be sure that we do indeed exist? We are left, then, with an assumption that rules out the possibility of either being a brain in a vat or having any confidence in the assumption. As such, it is akin to a petitio principii, i.e. begging the question.

Second: I see no reason to deduce from existence the ability to refer to things and have intentionality. Lower animals certainly exist, yet we normally don't think that they have any kind of intentionality. Likewise, comatose people exist, but they can neither refer to things nor do they have intentionality.

Third: The conclusion, as I see it, rests on the argument that intentionality and being a vatted brain are contradictories, i.e. to be an intentional being means to be something other than a brain in a vat. I see no reason, however, to conclude that intentionality and being a brain in a vat are contradictories.

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This is Putnam's argument. But let me say this - am I just a brain in a vat?

If I indeed were - did I just talk about it even though I have no evidence about this vatness? I don't think so. I think Putnam is saying that we can postulate the possibility of my being 'envatted' but we can not talk intelligently about it.

This is the reason that Neo could not talk intelligently about being envatted before Morpheus revealed to him that he was 'enslaved' from outside it. The Matrix would make no sense unless they start the movie from the position outside the matrix.

TTF

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Re: brains in vats
As I said, it's our conception of the world that would be illusory. Not our sensations.
And yes, I believe we can imagine things we never experienced. This topic is a very good example.

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I agree Val,

It is the difference between active and passive nous as Aristotle defined it.

Passive nous is just our sensory experience and it cannot be wrong. What we see is what we see.

Active nous is the judgments we make about those perceptions. Those can be wrong - in this case as Val correctly pointed out that it is our perception that the envatted experiences are real that is wrong.

However, there are convincing arguments to the contrary - check here:

http://whatisthematrix.warnerbros.com/rl_cmp/new_phil_brain.html

ttf

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Putnam's argument does not convince me, because it emplies a concept of reality, exterior to the brain in the vat. Using Putnam's criteria, the possibility of defining reality, for us who live inside that reality, is so problematic as the possibility of the brain in the vat define it's own reality.
Besides I dont believe that a word implies the existence of a correspondent object in "reality" (what reality?).

thethinkfactory wrote:

it.

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Mr Ockham has a razor. Let's ask him for the most likeliest explanation.

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We exist.
We exist --> We have intentionality.
We exist as brain in vats --> We do NOT have intentionality.
We do NOT exist as brains in vats.

How's that? Confused

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agrote wrote:

We exist.
We exist --> We have intentionality.
We exist as brain in vats --> We do NOT have intentionality.
We do NOT exist as brains in vats.

How's that?

Unsound.

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joefromchicago wrote:

agrote wrote:
We exist.
We exist --> We have intentionality.
We exist as brain in vats --> We do NOT have intentionality.
We do NOT exist as brains in vats.

How's that?

Unsound.

Okay, but why?

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agrote: because there is no reason to accept any of your premises. At most, you have constructed a valid syllogism (albeit backwards); you have not, however, constructed a sound argument.

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Don't forget it's not my arguement.

But it's valid, right? The conclusion follows from the premises.

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if we were 'brains in vats'; reality would 'be' the 'matrix' which we are fed.

reality is our experience, and we can manipulate it to suit our needs.

[even if it does not exist!]

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agrote wrote:

But it's valid, right? The conclusion follows from the premises.

I believe so. I think you may have too many terms here, but I'm not going to work it out. Furthermore, as I mentioned, it's backwards. Here's what you wrote:

We exist. We exist --> We have intentionality. [u]We exist as brain in vats --> We do NOT have intentionality.[/u] We do NOT exist as brains in vats.Typically, the major premise precedes the minor premise. So, for instance:

All men are mortal (major premise) [u]Socrates is a man(minor premise)[/u] Socrates is mortal(conclusion)In your syllogism, "we exist" is a minor premise, so it should immediately precede the conclusion "we do NOT exist as brains in vats." Your other two statements are both major premises.

Note: just because you've constructed a valid syllogism doesn't mean that your conclusion is true, it just means that it is logically valid. Stating:

All unicorns are white [u]This is a unicorn[/u] Therefore, this unicorn is whitedoesn't establish the existence of unicorns.

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How does the order of the premises make any difference?

I know the conclusion isn't necessarily true, I was just making sure you agreed that the argument was valid.

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The predicate in the major premise must be the predicate in the conclusion. Likewise, the subject in the minor premise must be the subject in the conclusion. This is the logical order that leads to valid syllogisms because you are trying to link the subject of the major premise to the subject in the minor premise.

Take Joe's Syllogism:

All unicorns are white.
All animals identical to this one are unicorns.
Therefore all animals indentical to this one are white.

We need to link THIS animal to whiteness. If our conclusion was that all white things are identical to this animal - you can see we have said something that is not true and all we have not sound (nor logically derived from the syllogism)

TTF

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