I may be totally off the target, but in my opinion the BIV has no sensations; no ways of taking in impulses from the physical world, due to its lack of skin, sight, hearing, touch, and smell and taste.

So it is so alone, that it has no way of knowing it is alone by itself.

It can't have any idea that there is a physical world, therefore it can't have any motivation to communicate with the world.

Therefore his motivation lacking, he has no intention of anything, let alone intention to represent itself.

Furthermore, it may not even have a concept that it, itself is something. Not in a coma, but nevertheless completely devoid of any structural instructions ever, it may not realize its own self.

Long story short: the idea of self-identity is very much contingent upon the views by the self, which views the separation of the self from the outside world generates for the self along with a number of corollaries and considerations. The brain in the vat has no capacity for noticing this separation.

On a semantic externalism view of meaning, a BIV cannot mean that it's envatted, because it can only refer to the sensations provided by the vat program. Putnam does have to arrange the argument a certain way so that the reference to brains in vats cannot be anything but the programmed sensation. So a person envatted last night could mean actual envatted brains, but a universe of just envatted brains hooked up together could not.

One wonders how Neo in the Matrix could understand what Morpheus was talking about when offered the blue and red pills. And the answer was he could not, he could only be shown. The choice was whether to go down the rabbit hole, or continue living a normal life. It was only after Neo got unplugged that he could understand his situation.

This kind of skeptical scenario is a problem for meaning not being in the head. If the environment provides meaning, but the environment is fake, then one cannot understand the environment being fake. Yet we seem to be able to understand simulation, dream, Matrix and evil demon arguments. So either we can know the environment is not fake, or semantic externalism is false.

Doesn't semantic externalism require some kind of distinguishability? If BiV is phenomenally the same as not-BiV, then I don't see how semantic externalism can do any work. Even someone who is not-BiV would not know what they meant by real and not real.

Just to be clear: I know that none of us are brains in vats; we are all living in reality.

It seems to me that having an experience of eating pizza cannot be simulated. That is because my experience of reality requires more than BiV, it requires sensory organs that can experience the reality. The proof is in the pudding, or in this case, the pizza. I think that if you remove the sensory abilities of the organism, you remove phenomenal consciousness too, or at least you remove the phenomenal consciousness of what is sensed. Experience is a more integrated process than just brain processing, in my opinion.

BiV scenarios are implausible because mindless matter cannot produce minds. You can't get consciousness from non-conscious stuff. In support of this assertion is the continued failure of science to come up with a solution for the mind-body problem.

https://www.scientificamerican.com/article/a-25-year-old-bet-about-consciousness-has-finally-been-settled/

Scientists will keep losing these bets. Eventually, people will abandon the metaphysical assumption that matter exists. Idealism is true. BiV problem solved!

My view also. In any case, are we not already brains in vats?

Doesn't semantic externalism require some kind of distinguishability? — NotAristotle

Semantic externalism is a consequence of the causal theory of reference. Words can only refer to things if these things have had some relevant causal affect on the development and use of these words.

If Neo is in the Matrix and there is a tree outside the Matrix then none of Neo's words can refer to this tree. What the word "tree" means and refers to for him isn't what the word "tree" means and refers to for those of us living outside the Matrix.

Given that if metaphysical realism is true then something like us living in the Matrix is possible, Putnam's argument is that metaphysical realism and semantic externalism are incompatible, and because he believes that semantic externalism is true he concludes that metaphysical realism is false.

It seems to me that Putnam's argument is question-begging. SEP seems to basically agree. https://plato.stanford.edu/Archives/spr2009/entries/brain-vat/

What specifically is question-begging? The argument as I understand it is:

1. If metaphysical realism is true then we could be brains in a vat
2. If semantic externalism is true then we cannot be brains in a vat
3. Semantic externalism is true
4. Therefore metaphysical realism is false

It isn’t obvious to me that the conclusion is contained in one of the premises.

2 is question begging. If semantic externalilsm is true, we could still be BiV.

His paper is an attempt to show that if semantic externalism is true then we cannot be brains in a vat, so it doesn’t make sense to claim that it’s question begging. You can argue that his reasoning isn’t valid, but that’s not that it begs the question.

But he assumes that we are not BiV in proving it. Isn't that begging the question?

But he assumes that we are not BiV in proving it. — NotAristotle

He starts by defending semantic externalism, then by trying to show that if semantic externalism is true then we cannot be brains in a vat, and so concludes that we are not brains in a vat.

Would you mind laying out the argument as you see it, and we can both evaluate whether it is valid (or unsound by being question-begging)?

In the earlier argument you gave, I objected to premise 2. I don't consider the argument invalid, but I do consider premise 2 a faulty assumption.

Again, if you lay out the argument, I think we will both have an easier time evaluating Putnam's argument.

It seems to me that having an experience of eating pizza cannot be simulated. That is because my experience of reality requires more than BiV, it requires sensory organs that can experience the reality. The proof is in the pudding, or in this case, the pizza. I think that if you remove the sensory abilities of the organism, you remove phenomenal consciousness too, or at least you remove the phenomenal consciousness of what is sensed. Experience is a more integrated process than just brain processing, in my opinion.

Not only that, but the BiV argument removes the entire body, replacing it with "a vat of nutrients which keeps the brain alive" (Putnam, Brains in a Vat). The assumption that the body only keeps the brain alive and does not factor into phenomenal experience is a materialist form of dualism that ought to be dismissed as nonsense.

Given the causal theory of reference, the word “A” can only refer to some object B if that objects stands in a particular causal relationship to the word, e.g I see a B and intentionally coin the word “A” to refer to it.

I am a scientist and I have a human brain in a vat. The brain is conscious, much like me, except its experiences are elicited by a computer directly stimulating the sensory areas of the brain.

None of the words in this brain’s language can refer to the vat because the vat does not stand in the particular causal relationship that is required for it be the referent of a word. Every word in this brain’s language refers only to some feature of its artificial experiences. Even if it has a language that superficially resembles English, what it means by “brain in a vat” isn’t what I mean by “brain in a vat”. What it means by “brain in a vat” is what I mean by “simulated brain in a simulated vat”, and given that it isn’t a simulated brain in a simulated vat, the sentence “I am a brain in a vat” in its language is false.

The assumption that the body only keeps the brain alive and does not factor into phenomenal experience is a materialist form of dualism that ought to be dismissed as nonsense. — NOS4A2

Agree.

The assumption that the body only keeps the brain alive and does not factor into phenomenal experience is a materialist form of dualism that ought to be dismissed as nonsense. — NOS4A2

If you prefer, consider instead a body in a vat. It’s the same principle. This person never sees trees, only “hallucinations”, but if the causal theory of reference is true then none of the words in its language can refer to (real) trees.

Yep, so let's say you unvat the brain and give them eyes, a nose, etc. And you say to them "that is a tree." And they're like, "yeah, I know." And then you say to them, "no, that's a real tree." They'd be like "yeah, I can see that, but what do you mean by a 'real' tree." And you'd be like, "a real tree is not a BiV tree." But of course you'd be assuming that the tree you were pointing to was not a BiV tree. And that's the problem. There's no reason that you, the scientist, are not also a brain in a vat. The semantic externalism argument against BiV only goes through by assuming not BiV.

And you'd be like, "a real tree is not a BiV tree." But of course you'd be assuming that the tree you were pointing to was not a BiV tree. And that's the problem. There's no reason that you, the scientist, are not also a brain in a vat. The semantic externalism argument against BiV only goes through by assuming not BiV. — NotAristotle

It’s a real tree given what “real tree” means in my language.

The point still stands that if semantic externalism is true then none of the words in the brain’s language can refer to the vat.

Of course you could just deny semantic externalism, as I do.

The point still stands that if semantic externalism is true then none of the words in the brain’s language can refer to the vat. — Michael

I agree with you, but that's different than saying that if semantic externalism is true then we cannot be brains in a vat.

It’s a real tree given what “real tree” means in my language. — Michael

Except that the "real tree" might actually be referring to a BiV tree and that's the issue. As you said, if semantic externalism is true, no attempts by us to refer to a "real tree" would be successful if we are in BiV world.

If it's a body in a vat we're getting a lot closer to reality. And is this body actually fed pizza, etc. But then it would just be experiencing reality.

I agree with you, but that's different than saying that if semantic externalism is true then we cannot be brains in a vat. — NotAristotle

It entails it. No sentence in the brain’s language can refer to the fact that it is a brain in a vat.

If you prefer, consider instead a body in a vat. It’s the same principle. This person never sees trees, only “hallucinations”, but if the causal theory of reference is true then none of the words in its language can refer to (real) trees.

To be the same principle the body would in some way need to be silenced, or asleep, or unconscious, as in the movie Matrix. Of course, in these states he wouldn't be seeing or hallucinating anything, but dreaming. If the rest of the body is included, awake, and in full working order it would notice that it is in a vat, that it cannot move, is suspended in some sort of liquid, and so on, and his words could directly refer to the environment.

To be the same principle the body would in some way need to be silenced, or asleep, or unconscious, as in the movie Matrix. — NOS4A2

Sure. The point is that its experiences are elicited artificially by a computer directly manipulating the sense organs.

It never sees a tree or a brain or a vat and as such no words in its language can refer to these things.

Sure. The point is that its experiences are elicited artificially by a computer directly manipulating the sense organs.

It never sees a tree or a brain or a vat and as such no words in its language can refer to these things.

I don't see how it is possible. Much of the sense organs and their sensual periphery point outward, and as such any direct manipulation would require the manipulator to work external to the body, like a sort of VR headset. In that case, he would directly see the headset and would directly refer to that headset, or at least to whatever appears on the screen. I suspect this problem is why Descartes and others need to imagine themselves without bodies in order for their thought experiments to work.

In that case, he would directly see the headset — NOS4A2

No need for a headset. Just shoot beams of light into the eyes in various shapes and patterns and colours that generate the image of a tree.

To be the same principle the body would in some way need to be silenced, or asleep, or unconscious, as in the movie Matrix. — NOS4A2


Sure. The point is that its experiences are elicited artificially by a computer directly manipulating the sense organs. — Michael

I think the point NOS4A2 was making (correct me if I'm missing the mark NOS4A2) is that someone arguing for BiV faces a dilemma. If the person is awake, they are aware that they are BiV. If the person is not awake then they are sleeping or dreaming and are not aware of BiV. In either case, the person is not fooled by BiV.

If the person is awake, they are aware that they are BiV. — NotAristotle

Not necessarily. You’ve been arguing that we might be brains in a vat despite the fact that we’re not aware that we are.

Even awake, the brain and/or body only experiences what the computer makes it experience. The brain and/or body is cut off from every other kind of external sensory stimulation.

It’s logically possible, and that’s enough for the hypothesis to have philosophical significance.

No need for a headset. Just shoot beams of light into the eyes in various shapes and patterns and colours that generate the image of a tree.

But wouldn't he be referring directly to the light and the patterns, even if he mistook them for a real tree?

But wouldn't he be referring directly to the light and the patterns, even if he mistook them for a real tree? — NOS4A2

Sure, in that case he can refer to light and shapes and colours just as we can. But he can’t refer to trees and brains or truthfully claim that the things he sees are fabrications.