It is only an illusion to those of us who know the stick is straight, but see the image contradicting what we know. — Patterner

But the thing is the image does not "contradict what we know". To those who understand how light travels through water, the image is a straightforward representation of reality, no-one is getting fooled.

If consciousness is an illusion, then what is it that knows what's really going on, but perceives a contradiction? — Patterner

Illusionists do not believe consciousness is an illusion, only phenomenal properties. If you believe phenomenal properties are by definition necessary for consciousness, or that phenomenal properties are necessary for perception, I guess it amounts to the same thing. But I think that is a very trivial argument, basically laying claim to as many words as possible to increase the odds of the Illusionist undermining themselves with careless language.

It is only an illusion to those of us who know the stick is straight, but see the image contradicting what we know.
— Patterner

But the thing is the image does not "contradict what we know". To those who understand how light travels through water, the image is a straightforward representation of reality, no-one is getting fooled. — goremand

True, it does not in a literal sense. But it does in an illusory sense. That's what gives us the sense of wonder and makes us laugh. No, the magician didn't break any laws of physics, and what she did was not a contradiction of reality. But I *know* she put the ball in her hand. I saw her so it. So htf is it in my pocket?!?

If consciousness is an illusion, then what is it that knows what's really going on, but perceives a contradiction?
— Patterner

Illusionists do not believe consciousness is an illusion, only phenomenal properties. If you believe phenomenal properties are by definition necessary for consciousness, or that phenomenal properties are necessary for perception, I guess it amounts to the same thing. But I think that is a very trivial argument, basically laying claim to as many words as possible to increase the odds of the Illusionist undermining themselves with careless language. — goremand

I'm not sure of the wording "phenomenal properties are by definition necessary for consciousness." More like "phenomenal properties wouldn't exist without conscious." Without consciousness, there would be nothing but particles and groups of particles, interacting as their properties and the laws of physics determine. But we have consciousness, and the physical interactions are accompanied by subjective experience/phenomenal properties. The Hard Problem of Consciousness being figuring out why/how it is not just physical interactions. So no, I don't think it's trying to lay claim to words inappropriately. (Love your last sentence!)

we have consciousness, and the physical interactions are accompanied by subjective experience/phenomenal properties. — Patterner

As I said in the OP I don't agree with this, I am skeptical of phenomenal properties and argue that there is no "appearance of the phenomenal" (as opposed to the appearance being an illusion).

Try to look at this from my perspective, you make an assumption (the existence of phenomenal properties) and this assumption creates a philosophical problem that is so difficult it is called the Hard Problem with capital letters. I think it's worth considering whether this was a safe assumption to make in the first place.

I don't think it's trying to lay claim to words inappropriately. (Love your last sentence!) — Patterner

Thank you, it is unfortunate but there is a bit of a diplomatic aspect to this debate where whomever is allowed to define the terms of mental language gain a lot of rhetorical clout. I would prefer functionalist definitions of course.

[

I am skeptical of phenomenal properties and argue that there is no "appearance of the phenomenal" (as opposed to the appearance being an illusion). — goremand

I agree with your point of view. But I'm inclined to be a bit more than sceptical of phenomenal properties, understood as a kind of screen or veil between us and reality. I think the idea is based on a naive realist view of language.

We sometimes think we see something that doesn't exist (as in Macbeth and his dagger). We say that Macbeth is hallucinating a dagger, which is correct. Anyone who isn't paying attention will be tempted to say that Macbeth is seeing a hallucinatory dagger. One can be forgiven, I suppose, for concluding that a hallucinatory dagger is an object like a dagger. But it isn't. It is a non-existent dagger and Macbeth is not seeing it. He is thinking that he is seeing it. If we insist that there must be something (some entity) that he is seeing, endless problems follow.

Illusions are a bit different. But there is the same temptation to think that we are seeing an illusion is an entity that we are seeing. But, as you say, an illusion is not an entity; it is a misunderstanding. There is a perfectly good explanation for making the mistake of thinking that the stick in water is bent and it is clear that there is no bent object of any kind involved (except possibly some light waves, which, strictly speaking are not bent, but refracted). The catch comes when we generalize. Physics explains to us what sound waves (or light waves or heat) are and how they explain our ability to see or hear feel what's going on around us. But then that old chestnut (!) about the tree falling in the forest arises and we feel we need to make a choice. Either the sound is there whether we hear it or not, or there is only a sound when we hear it. The choice is inappropriate, since we hear the sound when we interact with the sound waves. We can resolve the dilemma either way. It doesn't matter - unless one then wants to treat sounds as some mysterious entity between us and the tree.

Dennett's problem is that an illusion is only an illusion in the light of a description of reality and analysis of how things appear in terms of that description. He takes physics &co as not merely a description of reality, but as the description of reality. I call that a naive realist view of physics.

The idea that we perceive reality is often characterized as direct or naive realism. (I've never seen a view that one could characterize as indirect or sophisticated realism, which may be significant.) I'm sure you've noticed that I think there are naive views of some other things in circulation. I don't mean to be sarcastic, but characterizing a view from the outset as naive is hardly dispassionate.

It would be a mistake to cover all the ground in one go. I think that's enough for now.

Unfortunately, I'm a bit lost. I'm not well read on a lot of these things. I may use terms incorrectly, or misinterpret what is being said.

Phenomenal properties don't exist outside of our consciousness. Illusions don't exist outside of our consciousness. They aren't physical things that we perceive under certain circumstances.

But they exist. "Only" within our consciousness, sure. But that's still existence. They are the subject of the conversation. We have a lot of common ground when we discuss them. A magician doesn't do something, and hope somebody in the audience gets something out of it. Something objective is at play, and the magician works with it.

How am I doing?

I'm sorry. I made an assumption and I was wrong. You're doing well.

Illusions exist, all right. They are perfectly objective. The tricky bit comes when we try to explain what they are. And this matters because of the grand question what the phenomena that we experience through our sense are, and how they relate to physics.

Useful background for this is this idea of a category mistake. See Wikipedia https://en.wikipedia.org/wiki/Category_mistake

You need to go carefully here, because even though we say that illusions exist only in our consciousness, it's a metaphor. There's nothing wrong with that, until you try to make too much of it. Our consciousness isn't a place and doesn't have an inside or an outside. So the existence of illusions in our consciousness isn't like the existence of my lap-top in my house. Explaining the literal truth of the existence of illusions and other experiences complicated and difficult.

All of that makes perfect sense to me.

Excellent!

The next step is a standard move in philosophy. When we see something, there is something that we see - a table, a goal, etc. We can draw a diagram. (I wish I was more fluent with computers and could actually draw it, but you'll have to imagine it, or sit down and draw one.) There's a head on the left side of the page, facing towards the right side, and a table on the right side of the page; an arrow connects the eyes in the head with the table. In other words, seeing has an object and the person seeing the object is in a relationship to it; the two are entirely separate entities.

Now, the question is, when I see an illusion, what is the object that I see? The obvious answer is some kind of picture of a bent stick in my head. (The same argument applies to hallucinations, which is why I was going on about Macbeth, and it seems inescapable that the same model must apply to anything that I see.)

I maintain (and so do a lot of other philosophers) that this is a conjuring trick. But I don't want to go too fast, so I'll stop there for now to make sure you are not lost.

Now, the question is, when I see an illusion, what is the object that I see? — Ludwig V

Has that question been answered in regards to when I see an actual object? I might suspect it would be the same answer, even if the source material is different.

I maintain (and so do a lot of other philosophers) that this is a conjuring trick. — Ludwig V

Can you be more specific? Certainly, no part of my brain turns yellow and shapes itself like a rubber ducky if I see one floating in the water. So, yes, some thing that might be caught the conjuring trick. But how was it achieved?

Has that question been answered in regards to when I see an actual object? I might suspect it would be the same answer, even if the source material is different. — Patterner

I think it has, in the second paragraph. My point there is that the idea of an internal image makes better sense in the context of an illusion or hallucination. The argument then is that if we actually see internal images when we see an illusion or hallucination, it doesn't make sense to suppose that we only see images when something's gone wrong.

Certainly, no part of my brain turns yellow and shapes itself like a rubber ducky if I see one floating in the water. — Patterner

Curiously enough, Aristotle has a theory quite close to that. But no-one takes it seriously any more.

But how was it achieved? — Patterner

It's a trick of language. Some people have a name for it - nominalization. This is the term used in grammar for the process of inventing a noun that corresponds to a verb. You'll remember that in grammar a noun is defined as the name of a person, place or thing. This true, but can be very misleading.

If I say a) "I'm going out for a walk", that may be grammatically like b) "I'm going out for a cucumber". So if you just look at the grammar, you will likely think that a walk must be an entity somewhat like a cucumber. But b) means I am going out to get a cucumber and bring it back but a) means I am going out to walk. A cucumber is an object, but a walk is something I do.

This is where talk of categories kicks in. A walk and a cucumber are both nouns, but in different categories. There is an entity that is named or picked out by "cucumber". There is no entity that is named or picked out by "walk".

Similarly, "bent stick" picks out an entity, but "illusion of a bent stick" doesn't. It is a nominalized version of "thought the stick was bent".

The main reason for insisting that this is the right way to look at it is this. If we suppose that some kind of picture is conjured up in my brain when I see a stick bent in water, we have to explain what the process of seeing it (the internal picture) is like. Then you will find yourself wanting to suggest that there's a picture of the picture in my head. You'll realize you are on the brink of an infinite regress, and so that there is something wrong. Positing the picture in my head doesn't explain seeing, much less my mistaken seeing. The story of the light getting bent as it passes through the water is all the explanation we need.

I hope that's helpful.

Has that question been answered in regards to when I see an actual object? I might suspect it would be the same answer, even if the source material is different.
— Patterner

I think it has, in the second paragraph. My point there is that the idea of an internal image makes better sense in the context of an illusion or hallucination. The argument then is that if we actually see internal images when we see an illusion or hallucination, it doesn't make sense to suppose that we only see images when something's gone wrong. — Ludwig V

I don’t understand what you mean by “we actually see internal images” or “ it doesn't make sense to suppose that we only see images when something's gone wrong.”

Honestly, I don’t know that I’m in the right thread. My apologies to . I don’t know that illusions are as relevant to what I’m thinking as hallucinations and dreams are. It’s not a physical thing. As we said, no part of my brain changes color or shape. There’s no image being projected onto a tiny movie screen in my head. I’m thinking that, whether the image I have in my head is a representation of an external object that my senses perceive, or an hallucination or dream, the nature of the image is the same.

Maybe a better concept is a fantasy. If there is something there or not, we have a desire that it, for example, serve a certain purpose (reference to an appearance) that it, perhaps, hold a place to allow or close off interpretation. Whatever the object and purpose, the fantasy is from the desire for a certain outcome.

While I'm not super comfortable speculating on the psychology behind belief in illusions, I think it's a fact people prefer to fix their beliefs and dislike suspending their judgement. Belief in illusions at least allow us to "externalize" (i.e. blame on something else) our inevitable errors. Like that stereotypical guy who thinks every woman is flirting with him, so it becomes their fault when he gets turned down.

I don’t understand what you mean by “we actually see internal images” or “ it doesn't make sense to suppose that we only see images when something's gone wrong.” — Patterner

Quite right. I shouldn't have allowed habitual forms of speech to take me over. But it illustrates how difficult it is to avoid misleading ways of putting things - especially when you're trying to demonstrate that certain ways of putting things are misleading. I'm sorry.

It follows that you are not on the wrong thread.

It is better (i.e. less misleading) to say that when we see an illusion of a bent stick in water we don't see an image of a bent stick, but we see a straight stick as bent. No image is required. I think this is what is saying. I also think that disposes of illusions.

I extended the discussion to hallucinations, dreams, etc. to register that there are other cases of getting things wrong that are less amenable to this kind of explanation. It is very hard to maintain that when Macbeth hallucinates his dagger he is misinterpreting something that he is really seeing. (Dreams are even more difficult, because we are asleep (i.e. unconscious) while we are dreaming.) The psychological explanation that Shakespeare expects us to adopt is that Macbeth is secretly guilty, but that doesn't help philosophically. I don't have a pat answer to that, so to avoid misleading you any further, I'll stop there, at least for the time being.

Does that help?

It is better (i.e. less misleading) to say that when we see an illusion of a bent stick in water we don't see an image of a bent stick, but we see a straight stick as bent. No image is required. I think this is what ↪goremand is saying. I also think that disposes of illusions. — Ludwig V

I understand the difference in the two ways of wording it in your first sentence, and it makes sense to me. However, rather than disposing if illusions, isn’t seeing a bent stick as straight (or seeing an image of a person projected onto a sheet of glass as a ghost, etc.) pretty much the definition of “illusion”?

I don’t know what to think about the word image. Again, there’s no literal image in my head, as there is on a movie screen. Still, if I close my eyes and imagine an apple, there seems some logic in saying I have an image of an apple in my head. Imagine and image having the same root, though image is possibly limited to the visual, while we can imagine things with regard to any of our senses, and then some. Can we say the verb does not result in the noun?

I extended the discussion to hallucinations, dreams, etc. to register that there are other cases of getting things wrong that are less amenable to this kind of explanation. It is very hard to maintain that when Macbeth hallucinates his dagger he is misinterpreting something that he is really seeing. (Dreams are even more difficult, because we are asleep (i.e. unconscious) while we are dreaming.) The psychological explanation that Shakespeare expects us to adopt is that Macbeth is secretly guilty, but that doesn't help philosophically. I don't have a pat answer to that, so to avoid misleading you any further, I'll stop there, at least for the time being. — Ludwig V

Is there reason to believe MacBeth’s hallucination of a dagger and his perception of an actual dagger are not of the same nature, even though they come about by different means?



Thank you for your posts.

It is better (i.e. less misleading) to say that when we see an illusion of a bent stick in water we don't see an image of a bent stick, but we see a straight stick as bent. No image is required. I think this is what ↪goremand is saying. I also think that disposes of illusions. — Ludwig V

How I would put it is, the straight and the bent stick *share* the same appearance. If X looks like Y, then Y looks like X, it goes both ways. I might as well say that a bent stick is an illusion because it looks like a half-submerged-in-water straight stick.

It is very hard to maintain that when Macbeth hallucinates his dagger he is misinterpreting something that he is really seeing. — Ludwig V

I actually think this could be argued, a hyper-rational Macbeth could glean some insight into his own state of mind if he interpreted the "dagger" correctly. Something like: "I perceive the appearance of a dagger, but I know there is none. The appearance must have some other explanation, perhaps it is a manifestation of my guilt."

The difference between hallucination and illusion in my opinion is where we assign the blame, illusions are blamed on the "deceitful appearances" of some objects, hallucinations are blamed on the "faulty" perceptual or cognitive apparatus of the subject.

Is there reason to believe MacBeth’s hallucination of a dagger and his perception of an actual dagger are not of the same nature, even though they come about by different means? — Patterner

It depends what you mean by "of the same nature". They are clearly radically different, since there's no dagger. But they are clearly similar because Macbeth is behaving as if there is a dagger in front of him. The question is whether the similarity can only be explained by positing something dagger-like in his head or mind. I know it seems mysterious. But if you approach the question in a different way, it will seem (as it has seemed to many philosophers) the best and only explanation possible. This is why philosophy is hard.

How I would put it is, the straight and the bent stick *share* the same appearance. If X looks like Y, then Y looks like X, it goes both ways. — goremand

Yes, of course it goes both ways. So I could easily see a bent stick in water as straight. The issue is that the phrase in italics and the phrase in bold seem to be equivalent, but actually suggest different models of what's going on. The italics phrase suggests that the illlusion must involve some thing called an appearance, and that's where the fault is. The bold phrase suggests something more like your way of putting it, that the illusion does not involve any thing except the stick.

hallucinations are blamed on the "faulty" perceptual or cognitive apparatus of the subject. — goremand

I doubt anyone would question that. The issue is what kind of fault it is. Perhaps the quick way of explaining it is that it is a question whether it is like an error in interpreting the data or like a faulty copy of a picture. I thought you were proposing the first alternative and rejecting the second.

I have to stop now, but since we started this exchange I've been thinking about it. Later on, I'll post a suggestion that might take us a bit further.

Is there reason to believe MacBeth’s hallucination of a dagger and his perception of an actual dagger are not of the same nature, even though they come about by different means?
— Patterner

It depends what you mean by "of the same nature". They are clearly radically different, since there's no dagger. But they are clearly similar because Macbeth is behaving as if there is a dagger in front of him. The question is whether the similarity can only be explained by positing something dagger-like in his head or mind. I know it seems mysterious. But if you approach the question in a different way, it will seem (it has seemed to many philosophers) the best and only explanation possible. This is why philosophy is hard. — Ludwig V

I’m only speaking of what my consciousness perceives, regardless of whether what it perceives is the result of signals from the retina, or the result of … whatever causes hallucinations. Either way, I see a dagger. My question is, are the two instances of my consciousness seeing a dagger - the moment of “Is this a dagger which I see before me?” Not what leads up to that moment - the same? At least as far as we can tell from any type of brain scan? Or could we look at brain scans and know that one is a hallucination? Maybe the vision centers of the brain are not active during (visual) hallucinations.

What do you mean by “ something dagger-like in his head or mind”?

"Illusionism claims that introspection involves something analogous to ordinary sensory illusions; just as our perceptual systems can yield states that radically misrepresent the nature of the outer world, so too, introspection yields representations that substantially misrepresent the actual nature of our inner experience." — goremand

But the very fact of having an inner experience is evidence in favor of the hard problem. If color and sound are illusions, those experiences still need to be explained in terms of how the brain produces them in a way that avoids the hard problem. Calling them interpretive illusions doesn't dissolve the matter. Just shifts it over to explaining how the brain accomplishes these illusions.

It's what Chalmers has called the meta-problem of consciousness.

But the very fact of having an inner experience is evidence in favor of the hard problem. — Marchesk

Not really, unless an "inner experience" is taken to involve phenomenal properties by definition.

Calling them interpretive illusions doesn't dissolve the matter. Just shifts it over to explaining how the brain accomplishes these illusions. — Marchesk

I don't think I ever spoke of "interpretive illusions". I don't think there can be such a thing, as interpretations don't have an appearance, they are just propositions.

A mistaken interpretation is not an illusion but merely a mistake. Calling a mistake an "accomplishment of the brain" is pretty funny, but I don't believe that mistaken beliefs are some great mystery to the empirical sciences.

You still have the appearance of colors, pains, etc that need explaining. Claiming they don't have phenomenal properties doesn't explain away their appearance. What Chalmers argues is that if the hard problem is an illusion (that we have phenomenal experiences), then this illusion needs to be explained. How does the brain produce such an illusion?

Because otherwise, you haven't dissolved the hard problem. You've merely claimed that it's an illusion without showing how.

You still have the appearance of colors, pains, etc that need explaining. Claiming they don't have phenomenal properties doesn't explain away their appearance — Marchesk

I don't need to "explain away their appearance", the mechanisms of color vision and pain are not a great mystery and not what results in the Hard Problem. The great mystery of the Hard Problem are
the phenomenal properties of introspective states.

What Chalmers argues is that if the hard problem is an illusion (that we have phenomenal experiences), then this illusion needs to be explained. How does the brain produce such an illusion? — Marchesk

Answering that is not really my problem, as I do not believe phenomenal experiences are illusions. The whole point of this thread is to argue against Illusionism and to explain how skepticism of phenomenal properties does not entail Illusionism.

What do you mean by “ something dagger-like in his head or mind”? — Patterner

Something like a picture or a model.

But the very fact of having an inner experience is evidence in favor of the hard problem. — Marchesk

It certainly is, if such things as inner experiences exist. The issue is whether they exist. I read the Nagel's original account and carried out the thought experiment he proposed. Nothing. Am I deficient? A zombie? Hard to bamboozle?



Perhaps it's time to go nuclear. I think illusionism is circular. An illusion can only be defined by its difference from reality. If the deliverances of consciousness are illusions, what is the reality? Oh, yes, physics. How do we know that physics is an account of reality and that common sense is the illusion? By empirical evidence, of course. Where do we get empirical evidence? Naturally, the deliverances of consciousness.

The formulation of the hard problem is misleading. One day, perhaps, we will recognize that and develop less misleading ways of thinking about these things. But I'm not holding my breath.

An illusion can only be defined by its difference from reality. — Ludwig V

I believe this is not quite correct, I agree every illusion has a counterpart, "the thing that looks like itself", the thing that does not deceive, but this thing need not be real, only privileged. For example maybe you have seen Penrose triangle sculptures (the real sculptures, not images on paper)? These create the "illusion" of a physically impossible shape, in other words they are claimed to look like something that cannot possibly be real.

If the deliverances of consciousness are illusions, what is the reality? Oh, yes, physics. — Ludwig V

I think in the case of Illusionism, the counterpart would not be physics but phenomenological realism. The Illusionist says "phenomelogical properties appear to exist, but do not", the realist says "phenomelogical properties appear to exist, and do".

What do you mean by “ something dagger-like in his head or mind”?
— Patterner

Something like a picture or a model. — Ludwig V

If the matter inside our skulls does not take on the shape or color of whatever we’re thinking of, in what sense is there a picture or model in my head?

I read the Nagel's original account and carried out the thought experiment he proposed. Nothing. Am I deficient? A zombie? Hard to bamboozle? — Ludwig V

Can you direct me to this thought experiment?

The formulation of the hard problem is misleading. One day, perhaps, we will recognize that and develop less misleading ways of thinking about these things. But I'm not holding my breath. — Ludwig V

All matter has properties. From primary particles like quarks, electrons, and photons, to atoms, to molecules, on up to galaxies. We can study these properties. We know how these properties and the four forces produce the interactions that take place between everything.

Knowing all that, we can understand how various things are reducible to the physical. Perception, perceptual discrimination, memory, learning, on and on. Freakin’ monarch butterflies migrate from Canada to a relatively small part of Mexico, to roost on specific trees for the winter. They head back north in the spring, but die along the way, and the next generation continues the journey. It takes four generations of them to do a complete cycle. No monarch that flies to Mexico has ever been there before. I don’t imagine anyone thinks they have a great degree of consciousness, or that one generation teaches the next in order to make this happen. It’s all just physical. Massively complex, but physical.

I think the Hard Problem is explaining why/how the physical is accompanied by subjective experience, and awareness at different levels (of an event; of myself; of my own awareness). Butterflies have the physical without the subjective or awareness. We’ve built machines that can perceive, discriminate, react, and learn, but don’t have the subjective or awareness. If I did not hate the pain of burning my hand, the system of protecting the body would still pull my hand away from the fire. So why is the subjectivity and awareness there, and how is it accomplished? What, in addition to the physical, is there?

What do you mean by “misleading”?

I think in the case of Illusionism, the counterpart would not be physics but phenomenological realism. The Illusionist says "phenomelogical properties appear to exist, but do not", the realist says "phenomelogical properties appear to exist, and do". — goremand

H'm. We're talking about slightly different things. "Phenomenological properties exist" and "Phenomenological properties do not exist" are indeed contradictories. Whichever is true must be a contingent, empirical statement. Right? So where does the evidence that they exist, or not, come from?

We’ve built machines that can perceive, discriminate, react, and learn, but don’t have the subjective or awareness. — Patterner

Careful! There's a strict use of these words in which anything that perceives, etc. is by definition, conscious, aware, has subjective experience. In that use, that statement counts as personification - a metaphorical use of the words. So that isn't quite the hard problem.

explaining why/how the physical is accompanied by subjective experience, — Patterner

... once you have defined "physical" and "subjective experience", and said that one accompanies the other, you have defined them as distinct, not just as chalk and cheese are distinct, but categorially distinct. So the problem no solution in virtue of the terms you use to pose it. "Team spirit" - to use Ryle's example - is something distinct from the team members, yet it is not something distinct from the team.

A rainbow is distinct from the raindrops and light that create it. Yet it is an effect of the sunlight refracting through the raindrops, not an elusive something. There is no hard problem there, is there?

Can you direct me to this thought experiment? — Patterner

I'll have to hunt it down. I'll get back to you.

A rainbow is distinct from the raindrops and light that create it. Yet it is an effect of the sunlight refracting through the raindrops, not an elusive something. There is no hard problem there, is there? — Ludwig V

No, there is not. Because, as you just explained, we know how it happens, and it’s all physical. If a rainbow started showing signs of consciousness, we’d have a problem. We would not have any idea how physical things and processes that produce this thing we understand - the rainbow - also produce these other characteristics at the same time. Characteristics that are not reducible to sunlight refracting through raindrops.

H'm. We're talking about slightly different things. "Phenomenological properties exist" and "Phenomenological properties do not exist" are indeed contradictories. Whichever is true must be a contingent, empirical statement. Right? So where does the evidence that they exist, or not, come from? — Ludwig V

For evidence, I think the realist would say "Phenomelogical properties appear to exist, so they probably do exist", and the Illusionist would say "Phenomelogical properties result in unsolvable philosophical problems, so they probably do not exist".

No, there is not. Because, as you just explained, we know how it happens, and it’s all physical. — Patterner

Fine. But you don't want to say that rainbows don't exist just because they are fully explained by physical processes, do you?

Now, we don't know what is going on when Macbeth sees the dagger. Why can't we leave it at that rather than positing some dagger-like phenomenon in his head?

Characteristics that are not reducible to sunlight refracting through raindrops. — Patterner

I'm not sure what you have in mind in that sentence. Can you give an example or two?

For evidence, I think the realist would say "Phenomelogical properties appear to exist, so they probably do exist", and the Illusionist would say "Phenomelogical properties result in unsolvable philosophical problems, so they probably do not exist". — goremand

That's admirably concise. But "exist" is complicated, so we can't understand exactly what this means without looking at it a bit more closely. Dragons, rainbows, numbers, colours, crimes all exist. But their existence is different in each case, and none of them is the same as the existence of tables and trees. The insoluble problems arise when we try to say that their existence is like the existence of tables and trees - we end up chasing ghosts and wondering why we can never catch them. The illusion of the bent stick is not an object like the stick, only in my mind. That is a metaphor, because my mind isn't a place (where "place" is a location specified in three-plus-one dimensions - time and space).

So we need to understand the manner of existence of appearances - in other words, its category.

Do you know about the idea of a category mistake? There's a helpful entry in Wikipedia, if you don't.

I'm not pretending that's a magic wand, though Ryle seems to have thought it was. But it at least allows us to formulate the problem differently and escape the endless merry-go-round (or should that be sadly-go-round?) of the traditional debate.

No, there is not. Because, as you just explained, we know how it happens, and it’s all physical.
— Patterner

Fine. But you don't want to say that rainbows don't exist just because they are fully explained by physical processes, do you? — Ludwig V

Certainly not. I don’t know why you are asking me that. I never intended to suggest such a thing. Maybe I worded something badly? Rainbows do exist. And we understand the physical reductionist explanation for them.

Now, we don't know what is going on when Macbeth sees the dagger. Why can't we leave it at that rather than positing some dagger-like phenomenon in his head? — Ludwig V

We should not posit such a thing. I dare say that explanation is impossible.

Characteristics that are not reducible to sunlight refracting through raindrops.
— Patterner

I'm not sure what you have in mind in that sentence. Can you give an example or two? — Ludwig V

Sure. Sunlight refracting through raindrops does not bestow solidity to rainbows. Or audible output. Or the ability to store data. Or consciousness. It does the one thing it does. It makes a rainbow.

It may be that one physical process, or one set of physical processes, seems to produce more than one thing. Such as the process that leads to both lightning and thunder. But that’s just one thing that has visual and audible (probably more) characteristics. I don’t know if one process produces two truly different things. Like if sunlight refracting through raindrops lead to a rainbow that you could slide on. If we ran across such a rainbow, we would be very surprised. We would assume something else is at work, and go looking for it.

Physical processes lead to my brain being able to perceive, and discriminate between, frequencies of visible light. But distinguishing between frequencies of light is a different thing than what it is like to see blue and red. Understanding those processes in perfect detail does not describe experiencing colors, and does not help a person who sees in great detail, but is color-blind, understand what blue is. We should be surprised that physical processes that bring about the one also bring about the other. More so, in fact, than if we ran across a solid rainbow. Because lights and solidity are both physically reducible. If consciousness is physically reducible, no one has been able to figure it out. At least Christof Kochdoesn’t think so. We should assume something else is at work, and go looking for it.