So what happens when your visual cortex is stimulated directly, and you have a red visual experience? It is, after all, dark in the brain as you noted.

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↪unenlightened So what happens when your visual cortex is stimulated directly, and you have a red visual experience? It is, after all, dark in the brain as you noted. — Marchesk

We realists call that 'an illusion'. It's not a real red visual cortex, the way a red apple is a real red apple. This is a very useful distinction for a philosopher, that allows us to admit the possibility of error. Sometimes, one might mistake a stick insect for a stick, or a mirage for an oasis, or a bang on the head for a red glow in the sky.

But it does show where red originates. It doesn't travel from the apple into the head, riding along photons and electrons.

Is that a real head you're talking about, or an indirect impression as of a head? This is the problem I think you have, that I say there are red apples and I can see them, and you want to deny that using real heads, photons and cerebral cortexes. But I don't see how you can get to the reality of all these exotic materials when you cannot even find a red apple when it's pointed out to you.

Its an inference, and yes that opens the door to skepticism and idealism, but it is what it is.

An inference from what? Experiences in your head lead you to infer that the things you experience as outside your head are experiences in your head?

An inference from what? Experiences in your head lead you to infer that the things you experience as outside your head are experiences in your head? — unenlightened

Where else would the experiences be? They're not out there in the objects. They're not on our eyeballs, ears or skin. We have good empirical reasons to think the brain is responsible. That's why dreams, illusions and other experiences are possible. The flow of sensory information comes into the brain, not the other way around.

But yes, it does require an inference to a physical world responsible for our having a body that perceives the world. However, metaphysically speaking, there are alternatives. It's just the physical one fits science best.

Does this image of direct perception work for you?



My problem with it is the implicit assumption that the apple is red the way it looks red to the perceiver. In my view, the awareness of red is added by the perceiver.

My problem with it is the implicit assumption that the apple is red the way it looks red to the perceiver. In my view, the awareness of red is added by the perceiver. — Marchesk

If you were colourblind, then you as a perceiver would not be adding red to the apple - you presumably claim. But all your colour seeing friends would independently add red to the same apples and not to other ones. Explain how everyone knows to add red to the same apples.

Explain how everyone knows to add red to the same apples. — unenlightened

Their brains are stimulated to see red.

Explain how everyone knows to add red to the same apples.
— unenlightened

Their brains are stimulated to see red. — Marchesk

By telepathy? or by some feature of the apples?

By telepathy? or by some feature of the apples? — unenlightened

Electrical signals from the cones in their eyes.

Electrical signals from the cones in their eyes. — Marchesk

Bite the fucking bullet man. How do everyone's eyes get to signal the same apples as red? Is it telepathy , or is there something about the apples that tells the eyes to signal red? Or come up with another explanation that actually explains.

Dude, you know it's the wavelength of the photons. I don't know what telepathy has to do with anything. The difficult thing to account for is the redness, not the causal chain.

Dude, you know it's the wavelength of the photons. I don't know what telepathy has to do with anything. — Marchesk

Yes I do know its the wavelength of the photons that are absorbed and reemitted from the surface of the goddam apples because the goddam apples are red. It's called colour vision, and it's no great mystery to me. It becomes mysterious when you try and claim that the eyes somehow project redness onto the brain from nowhere.

It's called colour vision, and it's no great mystery to me. — unenlightened

And yet it is a great mystery to others. For example, how come wave lengths get coded in colours? Where does that happen?

And yet it is a great mystery to others. For example, how come wave lengths get coded in colours? Where does that happen? — Olivier5

In the paint shop, maybe.

Let's not get into the fine details just yet. Some of us are trying to grasp how we tell a red apple from a green apple, and think the difference is somehow in the brain. My suggestion is that if we consistently and independently agree about which apples are red and which are green (which we do), then either the apples are different or our brains are in direct communication by telepathy.

I favour the former explanation, and call the difference "the colour of the apples".

Some of us are trying to grasp how we tell a red apple from a green apple, and think the difference is somehow in the brain. — unenlightened

The colors we see are in the brain, because that's where the perception is formed. The cause comes from outside, but the cause is different from the colors seen. That different wavelengths activate different cones in our eyes, sending the resulting signals to the visual cortex, allowing us to discriminate red and green apples (as we call the color difference). But that gets turned into a color experience.

How do we know your red and my red are the same? We don't. We just know we can discriminate the same.

Bite the fucking bullet man. How do everyone's eyes get to signal the same apples as red? Is it telepathy , or is there something about the apples that tells the eyes to signal red? Or come up with another explanation that actually explains. — unenlightened

Dude, you know it's the wavelength of the photons. I don't know what telepathy has to do with anything. The difficult thing to account for is the redness, not the causal chain. — Marchesk

But as enlightened pointed out before, not everyone's eyes get the signal because we have color blind people. Where does the "physical" difference between those that are color blind and those that are not lie? If all else us the same, the apple, the light, etc, then why are there color blind people?

The apple isn't red. It is ripe. The light isn't red. Its an EM wave that has a 650nm wavelength.

The color is the effect, and effects are not their causes. The "difficult thing" is resolved by thinking of everything as information, not "physical" objects. Red is causal information about the ripeness if the apple, the level of light, and the state of your eyes and brain. The difficult part comes in trying to discern what part of red gives us information about just one of those things. We can't because red is single product of multiple interactions and all we have access to is the single final product.

If all else us the same, the apple, the light, etc, then why are there color blind people? — Harry Hindu

It's not all the same. Color blind people either have a defect in their eyes or in their brains.

The "difficult thing" is resolved by thinking of everything as information, not "physical" objects. — Harry Hindu

I'm not sure how this works for consciousness.

The apple isn't red. It is ripe. The light isn't red. Its an EM wave that has a 650nm wavelength. — Harry Hindu

Agreed. So where does the red come in to play? I agree that information comes into the brain from the senses interacting with the world. But then what?

if we consistently and independently agree about which apples are red and which are green (which we do), then either the apples are different or our brains are in direct communication by telepathy — unenlightened

People have disagreed about apple colours before. When they do, are they seeing a different apple?

Beside, there are also optical illusions about colour, whereby a similar objective hue is subjectively seen as two or more different colours. In this case, there is a demonstrable difference between the objective and the subjective.

The colors we see are in the brain, because that's where the perception is formed. The cause comes from outside, but the cause is different from the colors seen. — Marchesk

Well, speak for yourself. I see colours in the apples and don't see my brain at all. I see apples out there, not in my brain, and the apples are out there, not in my brain. Seeing an apple is not having an apple in the brain, and seeing something red is not having something red in the brain.

Speaking for myself, I experience looking out at the world from my eyes. But I know that's not how it works. I also know the colors I see are just a small part of the EM spectrum, and if I could see the entirety of it in colors, the world would like quite different. The apple would not be quite so red and solid looking.

Moral of the story is just because the world is experienced a certain way, doesn't mean it is that way.

It's not all the same. Color blind people either have a defect in their eyes or in their brains. — Marchesk

Right, so we continue troubleshooting. If we take one of each type of patient and prod their brains with a metal rod, does either one experience red? If the patient with a defect in their eyes experiences red but the latter patient does not, than that seems to imply that colors are generated in the brain, not by the eyes.

Agreed. So where does the red come in to play? I agree that information comes into the brain from the senses interacting with the world. But then what? — Marchesk

I'm not sure I understand your question. If everything is information, then the way we think about red apples as physical objects is wrong. Physical objects, like colors, exist only in the brain as digitized representations of an analog world.

We realists call that 'an illusion'. It's not a real red visual cortex, the way a red apple is a real red apple. This is a very useful distinction for a philosopher, that allows us to admit the possibility of error. Sometimes, one might mistake a stick insect for a stick, or a mirage for an oasis, or a bang on the head for a red glow in the sky. — unenlightened

How does one distinguish between the illusion of red and red that is not an illusion. Red appears the same way to me.

In this case, there is a demonstrable difference between the objective and the subjective. — Olivier5

Alas for the indirect realist, whenever there is a demonstrable difference between the objective and the subjective, it demonstrates that there is an objective, that we can be deceived about. Sometimes we are deceived, sometimes things are ambiguous, sometimes we disagree. And we can explore and describe the circumstances when this tends to happen, and learn that some people see better than others, and everyone has a blind spot and all sorts of interesting stuff. We do not find that we see in our brains.

if I could see the entirety of it in colors, the world would like quite different. The apple would not be quite so red and solid looking.

Moral of the story is just because the world is experienced a certain way, doesn't mean it is that way. — Marchesk

A classic.

If you were blind, apples wouldn't look like anything at all.

Moral of the story is you can't see them even if you can see them.

Alas for the indirect realist, whenever there is a demonstrable difference between the objective and the subjective, it demonstrates that there is an objective, that we can be deceived about. — unenlightened

Alas for the naïve realist, it also demonstrates that there is a subjective perception as well, that perception is distinct from its objects.

We do not find that we see in our brains. — unenlightened

I don't think that was ever said or implied. We represent, or model, in our brains.

Alas for the naïve realist, it also demonstrates that there is a subjective perception as well, that perception is distinct from its objects. — Olivier5

Not a problem for naive realists, I see the apple as distinct from my seeing already. Sometimes, when I peep round the back of what seemed to be a red apple, it turns out to be green on the other side. I still see it out there, not in my head.

The language of perceptions attempts to drive a wedge between the senses and the world, and create an 'inner world' of perceptions but then, folks will say, 'I don't see the outer world, I see this inner world of perceptions.' This is impossible unless I have inner eyes with which to see these perceptions and I do not.

No, I see the world. I see it partially, incompletely, in some aspects, from a point of view, with limitations and subject to errors. But it's the world I see and not my brain, I never see my brain or my perceptions or my inner world.

We represent in our brains. — Harry Hindu

Ok. We represent apples in our brains, and we represent our brains in our brains, and we represent ourselves in our brains and our eyes in our brains and our propensity to represent stuff in our brains.

And then what? does the representation of the eye examine the representation of the apple and feed the information to the representation of the brain? Where the representation of the representation of the eye in the representation of brain in the brain examines...

I think we'd do better to stick with the first presentation of the real apple to the real eye. See the red apple, climb the tree, pick the apple, eat. Yum.