Is it possible to perceive a world which is external to our perceptions?

[UndercoverElephant]

So the exact same simulation as the BIV but with your brain safely in your skull, the image sent to you by 3D goggles and your feedback registered by some kind of total immersion body suit (let's imagine one much better than we can actually build today) would merely be an illusion - we would be correctly perceiving the world around us.

We would be incorrectly perceiving the world around us, but we would be percieving an object in the real world, yes.

But if you accept this then we now have a scenario where the whole chain from the computer to the optic nerve is artificial, but we still believe the subject is perceiving an external, real world. How is this different from the perception of a supposedly unreal world in the case of the BIV (or even brain in the skull with wires attached)?

In this case there is no real world object at all. In the illusory cases there really is an object, we just make a mistake about what object it is. I have to argue that the BIV would know something was fishy - it would feel phenomenologically different.

Perhaps the defence doesn't work - I don't know. But if it doesn't, you are left with indirect realism and that certainly doesn't work.

 

[Paul C. Anagnostopoulos]

It seems that on your view, for visual perception to be perception of something real there needs to be a point in the chain of causation where light signals, corresponding to some kind of viewable image exist (potentially viewable by a human eye, that is). This is the only difference between the two cases - in the case of the BIV there are no light-emitting 3D goggles, it's electrical signals all the way from the computer to the brain. So, we can make the BIV perceive "real" objects simply by attatching the prosthetic eyes and 3D goggles (what a weird image) and hooking up the stimulus to the goggles rather than the optic nerve, which sems a little too easy. It is, after all, perceiving an identical virtual world in both cases.

I think Geoff is saying that light has nothing to do with it. After all, he's now denying that direct realism allows a causal cascade from object to perception. But he has resurrected direct realism by positing a direct link from object to perception via a quantum mechanical mechanism.

Of course, he still needs the indirect links, too. So he's really proposing a sort of quantum mechanico-indirect realism.

~~ Paul

 

[hammegk]

Not even close. Penrose is proposing an ensemble of tubulin molecules in a superimposed quantum state. The wave collapse triggers some unspecified "unit of consciousness" to stream into my brain. The wave collapse acts as a portal of some sort. But in order to have direct realism, the ensemble has to include the chair. In fact, it has to include all the objects involved in my perception, including my brain.

Sounds like nonsense to me too, but I also admit the same feeling vis-a-vis quantum computers.

And it has to account for all the other people looking at the chair at the same time, along with the cat and the mosquito. But some of these objects don't have tubulin, so it's more complicated then some sort of "tubulin coherency wave."

Is it actually known whether animals, or any lifeform with a neural system, do not have these tubulin molecules? I suspect this to be speculative; who would have been looking for that feature in other life?

 

[UndercoverElephant]

Okay, so, reversing our previous decision, we say that direct realism requires a "direct connection" between the object and my internal experience of it; no complex causal sequence is allowed. From this, we conclude that indirect realism becomes much more reasonable, since it no longer requires a movie and homunculus in the brain, but merely a simple causal sequence. After all, direct and indirect realism exhaust all the possibilities.

Ah, but there's the problem. There is another possibility, and it's anti-realism. That is the subtext to this argument. Anti-realism is the ant-lion at the bottom of the slippery slope.

 

[Soapy Sam]

The argument is not about whether or not an external reality exists. The argument is about whether we can directly perceive it.

Why are we limited to perception?

We can directly experience external reality without perceiving it.

 

[UndercoverElephant]

Why are we limited to perception?

We can directly experience external reality without perceiving it.

Can we? Explain please.

 

[Soapy Sam]

I can think of many examples.

Many things- explosions for example- can destroy a human's central nervous sytem before it could respond to the arrival of the event.

The experience is manifestly real, yet perception is not involved.

 

[Paul C. Anagnostopoulos]

Is it actually known whether animals, or any lifeform with a neural system, do not have these tubulin molecules? I suspect this to be speculative; who would have been looking for that feature in other life?

Only eukaryotes have tubulin, but prokaryotes have a related protein.

There is nothing magical about tubulin as far as QM is concerned, except that the molecule has two conformations. I suspect any cellular entity with multiple conformations could be the consciousness portal.

~~ Paul

 

[UndercoverElephant]

Paul and all.....

You all seem to have arrived at an agreement that direct realism is either very hard or completely impossible to defend. In which case the real problem is the fact that indirect realism is absolutely impossible to defend. If we can only ever be indirectly aware of external reality then what right do we have to consider external reality to be anything like our mere representations? Indirect realism is hopeless. The only conclusion left is to abandon realism altogether and finally accept Kant. We cannot know the noumenal world, so let's stop getting it mixed up with the objects of perception.

Geoff

 

[chriswl]

In this case there is no real world object at all. In the illusory cases there really is an object, we just make a mistake about what object it is.

But the person wearing the 3D goggles perceives a real world object. I'm saying that the BIV, fitted out with prosthetic eyes plus 3D goggles would be in exactly the same situation. It sees the inside of the goggles. But if we re-engineer the prosthetic eyes and goggles into one compact unit that takes the electrical signals that were inputs to the goggles and directly transforms tham into electrical stimulation to the optic nerve (i.e. we miss out the optical stuff) then this is back to the pure BIV scenario. How have we supposedly lost our objects of perception? Were they just the light in the goggles?

Perhaps the defence doesn't work - I don't know. But if it doesn't, you are left with indirect realism and that certainly doesn't work.

But the BIV thought experiment was supposed to show that real objects and unreal ones may appear to be the same, and when we perceive unreal ones we are just perceiving representations in our heads, so maybe that's all we ever do. I'm saying I don't accept the distinction between real and unreal objects. And I don't think you can pick out one stage in the chain of perception and say this is where the real object of perception resides (the chair, the inside of the VR goggles, the signals in our brain). The direct/indirect perception idea doesn't seem to be properly defined - no wonder philosophers have such trouble with it.

 

[Soapy Sam]

Let's see if I got that.

I think there is a problem.
I think there are two and only two solutions.
I can't make either solution work.
Therefore there's a problem with reality.

 

[Paul C. Anagnostopoulos]

Sounds about right, Soapy.

Although Geoff can make direct realism work with quantum mechanics, if he simply assumes that the QM interaction with the chair is giving him something more than "mere representations."

Geoff: You're still not interacting directly with the chair. And you're still not getting rid of brain processes mediating between the chair and your perception of it.

~~ Paul

 

[Bodhi Dharma Zen]

We cannot know the noumenal world...

And yet, it can.

 

[Mercutio]

So...anything by neurologists? Physiopsychologists? Neurophysiologists? Basically, anyone whose area of expertise includes functioning human brains? [snip]

Sorry, Geoff, but these people [physicists] are the wrong experts.

I don't agree. Their position is the same as mind - that the brain experts have got their metaphysics confused.

Thank you for saying this. I think I can safely ignore this thread now. There is no a priori reason that the physicists and neurologists would disagree on metaphysics. I would wager you'd find many physicists who disagree with the ones you refered to. You chose the ones who agree with you--the ones who take "mind" at face value.

 

[UndercoverElephant]

Sam

Almost....

I think there is a problem.
It looks like there are two and only two solutions.
I can't make either solution work.
Therefore there's a problem with [the way we naturally think about] reality

Geoff

 

[UndercoverElephant]

But the BIV thought experiment was supposed to show that real objects and unreal ones may appear to be the same, and when we perceive unreal ones we are just perceiving representations in our heads, so maybe that's all we ever do.

In which case you need to think back to the previous thread. What you are saying is that we never percieve real-world objects. All we ever percieve is representations in our mind of whatever-it-is that is "out there". At this point it isn't realism at all. We are only aware of human-neurology-dependent representations. Why claim that the "real world" is made of the same physical objects that we are now claiming are nothing but representations? Do you see how this thread follows from the last one?

I'm saying I don't accept the distinction between real and unreal objects.

Then you can't defend realism.

And I don't think you can pick out one stage in the chain of perception and say this is where the real object of perception resides (the chair, the inside of the VR goggles, the signals in our brain). The direct/indirect perception idea doesn't seem to be properly defined - no wonder philosophers have such trouble with it.

It's very clearly defined. Your viewpoint makes direct realism a total impossibility. But indirect realism is equally impossible.

For all:

This thread is a re-run of the last one. The only difference is that this time we started with the objects of perception, so nobody could deny they existed (although one Upchurch tried) or claim they were nothing but "brain processes". Now, instead of not being able to find a way to defend physicalism without denying a mind, we are left with no way to defend direct realism (No way to claim P1=P2) and the only alternative is indirect realism which just doesn't make sense, because the indirectness denies the realism. "Indirect realism" is either inherently dualistic or oxymorinic in exactly the same way reductive materialism is. Does anyone see the connection between this thread and the other one?


Geoff

 

[chriswl]

It's very clearly defined. Your viewpoint makes direct realism a total impossibility. But indirect realism is equally impossible.

It's only clearly defined if you can convince yourself that you know what you mean by "objects of perception". The BIV thought experiment completely deconstructs this concept. The only description of the scenario that doesn't lead to confusions and contradictions is the physical one. It's actually a great argument for materialism.

 

[Paul C. Anagnostopoulos]

Of course the threads are related.

Your defense of direct realism is not direct, either. In fact, since you have absolutely no idea how the QM solution would work, it's no sort of realism at all.

~~ Paul

 

[Paul C. Anagnostopoulos]

Say, I wonder if a BIV also receives non-neural inputs, such as ambient temperature. Might be important, you know.

~~ Paul

 

[UndercoverElephant]

Say, I wonder if a BIV also receives non-neural inputs, such as ambient temperature. Might be important, you know.

~~ Paul

You can carry out brain surgery without a brain anaesthetic. The brain feels no pain.