The Adelson Checker Shadow Illusion and implications

Art48

Some years ago, when I first read about the Adelson Checker Shadow Illusion, I was shocked. If you haven’t seen the illusion, here’s a link.

https://en.wikipedia.org/wiki/Checker_shadow_illusion#/media/File:Checker_shadow_illusion.svg

The article said that square A and square B were exactly the same color. I couldn’t believe it. They obviously are not. I printed out the image, but it looked the same on paper. I cut out square A and B and placed them side by side. They were the same color. Yet when I looked at the image, the squares were clearly not the same color.

I’ll return to the illusion in a moment. First, some background ideas.

We can see ourselves from two different perspectives.

From the outer perspective, I am a body in spacetime. A body with an inner consciousness, as demonstrated by my perceptions, emotions, and thoughts. I am conscious of seeing a cloud, of feeling happy, of thinking about dinner.

From the inner perspective, I am a consciousness which is aware of sense perceptions, emotions, and thoughts. We can divide up sense perception into sight, smell, sound, taste, and touch. We can divide thought into creative thought, as in writing a novel, and logical thought, as in following a mathematical proof. No matter how we divide, we get the subject, i.e., consciousness, which is aware of objects of awareness. The objects of awareness—sense perceptions, emotions, and thoughts—arise and then fade away, like waves in the ocean: they may change in a second: I’m looking at the sky and I turn to look at a tree; I’m feeling bored then a friend calls. The only thing that remains constant is our consciousness, our awareness.

It is an old thought in philosophy that the source of our sensations is unknown. We naturally credit the material world of spacetime as the source of our physical sensations. But, for all we know, the source could be Descartes’ evil demon. Or we might be a brain in a vat. Or living in a computer simulation. In Kantian terms, we directly experience phenomena, never noumena. It’s easy and natural to picture the source as the material world. And we may be correct. Or maybe not.

This seems to imply that the inner perspective is more certain, more epistemologically sound, than the outer perspective.

So, the case can be made that all we are directly aware of is our physical, emotional, and mental sensations. I don’t experience matter directly. Rather, I have visual and tactile sensations of a rough, green and brown object which I imagine to be a tree. The material tree I do not directly experience. Rather, visual and tactile sensations are the sum total of all I directly experience. Anything else, is conjecture.

Now back to the Adelson Checker Shadow Illusion. What it demonstrated to me is that I do not even directly experience physical sensations. In other words, in the illusion I do not see what my eyes see. My eyes see exactly the same color; the light from both squares has exactly the same wavelength. Apparently, my mind processes my visual perceptions, and I see the result of that processing. What I see is a product of my brain (outer perspective) or my mind (inner perspective). Not only do I not directly experience the exterior world, presumably a world of matter in spacetime. I do not directly experience what my eyes sense. Rather, I must conclude that I directly experience only my mind.

I’m not comfortable with the conclusion. But I don’t see a flaw in the argument. Does anyone else?

Angelo Cannata

You do not directly experience even your mind, because even the very concepts of “direct”, “experience” and “mind” are all constructions of our mind. We can go further, to a meta-level, and realize that even the conclusion that everything is a construction of our mind must be, of course, a construction of our mind. We might conclude that we never know what we are talking about, what we are perceiving, what we are thinking. Everything is filtered, contaminated, polluted, distorted, changed, and even by writing this very line I cannot say that I know what I am saying, what I am talking about.
All of this is just fine: it is just a result of the roughness of philosophy, despite our idea that philosophy is something very clever, very refined. It is just a very rough and weird playing with words, ideas, concepts, that were born to manage our existence in this world, to chase animals, to manage our social relationships. Imagine a dog who decides to elaborate his production of different ways of barking, feelings, reacting, to build a whole system that is supposed to get him an intellectual mastering about how the world is, how things work. This is philosophy. Obviously, an organized system of barking will never be able to master an understanding of the world. Curiosly, humans think they can, and then they are even surprised seeing that it doesn’t work.

wonderer1

Obviously, an organized system of barking will never be able to master an understanding of the world. Curiosly, humans think they can, and then they are even surprised seeing that it doesn’t work. — Angelo Cannata

Well "master" might be a bit grandiose. On the other hand we are discussing philosophy with people all over the world, so maybe it works somewhat?

Angelo Cannata

It cannot work. Thinking that it works, even just a little, means that we have some ability get access to the truth, to reality, to how the world really is. This is what some philosophers do, trying to save metaphysics, at least just a bit, seeing that metaphysics doesn’t work. But this isn’t so correct intellectually: metaphysics is not about a degree of validity. If one tiny bit of metaphysics works, it just means that metaphysics works, it doesn’t matter how much. But the problem with metaphysics is total, just because metaphysics itself is about the total, the universal. It is the very concept of truth itself that is pretentious, it is an attempt to definitely master the world, even if a specific philosopher can have a very humble heart and doesn’t realize how much will of power is contained in concept of “truth”.
Metaphysics cannot work because it is contradictory. Once we realize this, it means that every bit of it is contradictory, it doesn’t matter how tiny this bit is.

unenlightened

in the illusion I do not see what my eyes see. — Art48

It's not an illusion, it's a picture. It's not chequer square and a vase with a shadow, it's a picture thereof.

At no point do you or I actually see or think we see an actual vase or chequerboard. But one might for a moment mistake a picture for reality.

Your eyes, and my eyes do not see something other than what we see, because it is part of the act of seeing to make sense of the light entering the eye. And sense one makes, of "squares and shadows" is one that discards the irrelevant sameness of A and B in favour of the understanding that one is in shadow and the other in light, and they represent the different colour squares. To see them as the same is to misinterpret the image.

In the sense that seeing is remote, one gets news of the world indirectly by sampling and sorting the ambient light, one is not in direct contact with - not the chequerboard because there is none - but the screen, or the paper. But nevertheless, one sees what the artist intended; a chequerboard in which A and B are different colour squares. When you cut up the squares and destroy the image, you end up with diamond shapes about which one can say what one likes. Put one in a shadow, and they will look different again; turn one over and it will probably look white. One is not looking at the image, but at scraps of paper.

But how come you can cut up what you cannot see? How come you can then see the sameness that you cannot see. How for god's sake have you been convinced by a pile of mere words that you cannot see what you can perfectly well see?

unenlightened

Thinking that it works, even just a little, means that we have some ability get access to the truth, to reality, to how the world really is — Angelo Cannata

If I believed you, I would be rather more quiet. It is only because I do not believe your self-undermining pontifications that I am inclined to produce my own contrary ones. But why are you barking so loud?

Angelo Cannata

↪unenlightened

I cannot know why I am barking loud: it is like wanting to explain why we do philosophy. We just do it, we don’t know the reason. We don’t even know what “reason” means, so how can we know the reason?
You cannot believe me, because we believe what we think is truth, but I am not saying truth, I just bark.

wonderer1

It cannot work. Thinking that it works, even just a little, means that we have some ability get access to the truth, to reality, to how the world really is. — Angelo Cannata

The fact that we have some ability to get access to how the world really is, is what allowed for the construction of the internet which allows people to say such vacuous things as you say here, to others all around the world.

I hope you can learn to bark more meaningfully. Lots of other people do. Don't sell yourself short.

Angelo Cannata

↪wonderer1

Can you give any evidence that in what you said there is anything, even just a tiny bit, free from any conditioning of your mind?

unenlightened

evidence — Angelo Cannata

You are only going to get words and pictures on this site. That much is evident, but my finding it so is not evidence to you, just more barking. Seemingly nothing is evident to you; that's rather sad. Because even a dog's barking is more meaningful and communicative. A bark can be playful or warning mournful or aggressive. but you wouldn't know that I suppose.

It's odd, I had you down as more substantial than this blanket unassailable scepticism. Never mind, I'll know better next time even if you won't.

Banno

↪@wonderer1
Can you give any evidence that in what you said there is anything, even just a tiny bit, free from any conditioning of your mind? — Angelo Cannata

Is the argument here that one cannot think without using one's mind, therefore one cannot think?

Angelo Cannata

↪Banno

It is, but I cannot understand how you get the conclusion "therefore one cannot think".

Banno

But I don’t see a flaw in the argument. — Art48

What is the argument?

Consider, if you can, that you are aware of the situation. You understand that the two squares that look to be different shades are the same shade, and that this has been done in order to construct a picture of a partially shaded checkerboard.

The supposedly problematic central square is the shade it would be if we were looking at a real floor with one of the light checks in shadow.

There is no problem here, just a demonstration of how perceptions work.

So what is your argument?

You suppose two "perspectives" - first person and third. You posit that we cannot know what causes our sensations, despite the evidence to the contrary. You supose first person accounts to be "more certain" Then of a sudden you jump to "I do not even directly experience physical sensations".

There's no connection here between premise and conclusion.

Banno

↪Angelo Cannata

Ok, so if that's not your conclusion, what is?

Angelo Cannata

↪Banno

My conclusion is that, since we cannot think without using our mind, therefore whatever we think cannot claim any truth, any reality, any objectivity.

Banno

My conclusion is that, since we cannot think without using our mind, therefore whatever we think cannot claim any truth, any reality, any objectivity. — Angelo Cannata

You can see that the argument is invalid. It says "A, therefore B".

But it also contradicts itself, if it claims to be true; since if it is true, then we cannot claim it to be true.

So it doesn't seem right.

Banno

There is a rather slight argument supposing that because we sometimes see illusions, we therefore never see reality.

And yet, the one proposing this argument is certain that they see the illusion.

But of course no one here would propose anything so silly.

Art48

What is the argument? — Banno

The argument is in the OP.
The conclusion is that I don't even see what my eyes see.
Rather, I see what my mind interprets.
That's why do not appear to me to be the same color.

Angelo Cannata

↪Banno

I know this objection. I'm going to explain you the question.

If we say that everything is relative, we are forced, by the content of the statement, to apply it to itself: if everything is relative, it follows that the statement itself must be considered part of everything, so that it is to be considered relative. As a consequence, we are forced to conclude that it is impossible to say that everything is relative, because this statement makes itself relative. Actually, we can reveal a trick in this conclusion, because it chooses to accept and adopt a logic that has to be considered relative, that is, unreliable. Let’s see in detail how the trick works. What follows is the first sight, apparently correct and complete, of the reasoning:

1) we say that everything is relative;
2) we apply the content of the statement to the statement itself;
3) we conclude that the statement itself is relative.

Now let’s reveal and show the steps that are actually hidden and ignored in this reasoning.

1) We say that everything is relative.

1a) Hidden step. We accept and adopt the logic that allows to formulate the statement, in order to deduce its consequences.
2) We apply the content of the statement to the statement itself.

3) We conclude that the statement itself is relative.

3a) Ignored step. If the statement is relative, its logic cannot be adopted, because relative means unreliable.
3b) Ignored step. If its logic can’t be adopted, we must nullify point number 2).
3c) Ignored step. As a consequence, the statement “everything is relative” can’t be criticized, because, in order to criticize it, we need to make use of its logic, but we have seen that adopting its logic brings to negate its logic itself.

As is shown, once we have realized that everything is relative, we can’t carry on by applying the statement to itself. If we want to carry on with something, we need to adopt different logics, different structures, different languages and ways of reasoning.

If we think that, since its logic is invalid, then even point 1 must be negated, this conclusion, actually, doesn't take us to any better situation: we will have to face even more difficulties and contradictions.

Banno

The argument is in the OP. — Art48

Ok, so let's set it out clearly.

Suppose two "perspectives" - first person and third.
Posit that we cannot know what causes our sensations.
Supose first person accounts to be "more certain" than third person accounts.
Conclude that one doesn't see what one's eyes see.

Now I don't follow that. The argument is incomplete.

Contrary to your first assumption, we do often - although not always - know the source of our sensations. For example, the source of your sensation of this sentence is this sentence.

And it is a common supposition in the sciences and in law that third person accounts, being depersonalised, are better than first person accounts. That they are objective. We can be more confident about observations that can be repeated by others.

So I remain unconvinced.

↪Angelo Cannata

You seem to be saying that if we accept inconsistency, then we can no longer do logic.

Ok, but isn't a better conclusion that we ought not accept inconsistency? Conclude that not everything is relative?

And it doesn't address the invalidity of "...since we cannot think without using our mind, therefore whatever we think cannot claim any truth".

Art48

Suppose two "perspectives" - first person and third.
Posit that we cannot know what causes our sensations.
Supose first person accounts to be "more certain" than third person accounts.
Conclude that one doesn't see what one's eyes see.
Now I don't follow that. The argument is incomplete. — Banno

Here's a bare bones argument
1. I clearly see squares A and B are a different color.
2. Squares A and B in reality are the same color. Therefore, the light reaching my eyes reflected from squares A and B is the same color.
Conclusion: I do not see what my eyes see. Rather, my mind processes the light reaching my eyes and presents me with the image I do see.

Banno

I do not see what my eyes see. — Art48

There's a need for precision in the language used in situations such as this.

So one reply is that your eyes don't see - you see, using your eyes. Your eyes are a part of you.

Similarly, it's not that your mind process the information and presents it to you - as if your mind were not you - as you say with "my mind processes the light reaching my eyes and presents me with the image I do see".

Your eyes, the various parts of your optic nerves, the visual cortex - it's clearer to say these are the parts of your body you use to see rather than that saying that they produce the image you see, as if they were seperate from you. This helps avoid thinking in terms of the homunculus.

AmadeusD

- it's clearer to say these are the parts of your body you use to see rather than that saying that they produce the image you see, as if they were seperate from you. — Banno

No it isn’t.

Angelo Cannata

Conclude that not everything is relative? — Banno

We cannot conclude that not everything is relative, because this actually brings us to the contradictory consequence that everything is relative. Let me show the process. The starting point is

1) something is non relative.

But from here we have these consequences:

2) non relative means universal, that is, same for all subjectivities, able to take into consideration all subjectivities.

3) As a consequence, "universal" means able to take into consideration the subjectivity of those who say that something is universal.

4) If we consider that, whenever someone thinks that something is universal, this is always conditioned by their subjectivity, we have the consequence that the idea of "non relative" is always relative, which is equivalent to say that

5) everything is relative.

If we think that 5), as a consequence of itself, is relative and this takes us to the conclusion that something is non relative, we are taken back to point 1). But we have seen that point 1) has, as a consequence, its opposite, that is, point 5). Moreover, as I said before, we cannot apply point 5) to itself, because this would mean adopting a logic that it shows as being unreliable, because it is relative, as point 5) says.

In this situation, I think the best thing is to adopt point 5), but not considering it as an absolute statement, which would take us to point 1). Rather, we should consider the statement in point 5) as just the best we can conceive, the best way we have, as humans, of thinking about everything. This way we can adopt point 5) without considering it an absolute.

The Adelson Checker Shadow Illusion and implications

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