how do we know about any illusions at all?

Well, regardless of the question "how", it's not controversial to state that we DO experience illusions, and somehow we have ways of figuring out they're illusions. That's not controversial at all. It sounds like a failure of your intellectual creativity if you can't figure out ways to determine if any of our experiences are illusory.

and other people are part of the shadows one experiences. Other people's existence is questioned by questioning the idea that you see the world as it is. Once you start to question your experiences, you question everything's existence - including words and the people that use them. Solipsism logically follows from unfettered skepticism about the reality of an external world. — Harry Hindu

Metaphysical theories like this are hopeless, no evidence can be presented to cure this mental disease, and only demands some sort of persuasion to cure it. I find a good dose of humor can do the trick to expose the absurdity of such a position.

“As against solipsism it is to be said, in the first place, that it is psychologically impossible to believe, and is rejected in fact even by those who mean to accept it. I once received a letter from an eminent logician, Mrs. Christine Ladd-Franklin, saying that she was a solipsist, and was surprised that there were no others. Coming from a logician and a solipsist, her surprise surprised me.”

Bertrand Russell

how do we know about any illusions at all?

Well, regardless of the question "how", it's not controversial to state that we DO experience illusions, and somehow we have ways of figuring out they're illusions. That's not controversial at all. It sounds like a failure of your intellectual creativity if you can't figure out ways to determine if any of our experiences are illusory. — flannel jesus

I don't deny that we do experience illusions, but then to know that you are experiencing an illusion means that you have some sense of how the world is.

Besides, illusions are misinterpretations of sensory data. Our senses never lie, but we can misinterpret what they are telling us, just as you can misinterpret what someone is saying even though they are being truthful.

For instance, mirages and "bent" straws in water, are only illusions if you do not understand the nature of light. When you do not take into account that your eyes see light, not objects, then your direct-realist self is going to assume that you see objects as they are and then get confused with these illusions. But if you understand the nature of light, and that you see light, not objects, then mirages and bent straws is exactly what you would expect to experience. Your experiences become predictable.

Metaphysical theories like this are hopeless, no evidence can be presented to cure this mental disease, and only demands some sort of persuasion to cure it. I find a good dose of humor can do the trick to expose the absurdity of such a position.

“As against solipsism it is to be said, in the first place, that it is psychologically impossible to believe, and is rejected in fact even by those who mean to accept it. I once received a letter from an eminent logician, Mrs. Christine Ladd-Franklin, saying that she was a solipsist, and was surprised that there were no others. Coming from a logician and a solipsist, her surprise surprised me.” — Richard B

To keep yourself from sliding down the slope into solipsism, you need to come up with an explanation as to how we can know about the world even though "we don't see the world as it is".

instance, mirages and "bent" straws in water, are only illusions if you do not understand the nature of light. — Harry Hindu

I actually agree with you about those, but not all illusions are like that.

Take this album cover for example

https://en.m.wikipedia.org/wiki/Merriweather_Post_Pavilion_(album)

As my eyes scan across the image, I'm convinced shapes are moving and shifting. Of course they aren't, and I can figure that out analytically, and yet it seems so deeply true of my experience of the image, that I'm experiencing looking at moving shifting shapes.

Some illusions are perhaps conscious misinterpretations, but our experience of the world comes through a lot of filters before it becomes a conscious experience. The existence of those pre-experiential filters, which I think unambiguously exist, prove that we can't just be "experiencing reality as it is".

As my eyes scan across the image, I'm convinced shapes are moving and shifting. Of course they aren't, and I can figure that out analytically, and yet it seems so deeply true of my experience of the image, that I'm experiencing looking at moving shifting shapes.

Some illusions are perhaps conscious misinterpretations, but our experience of the world comes through a lot of filters before it becomes a conscious experience. The existence of those pre-experiential filters, which I think unambiguously exist, prove that we can't just be "experiencing reality as it is". — flannel jesus

This is due to a conscious effort of shifting one's attention to a specific area of the picture to the picture as a whole and back.

What does that even mean, "experience reality as it is"? Is your mind part of reality? Do you experience your mind as it is?

The fact that you know that there are unconscious filters is evidence that you are experiencing reality as it is.

You need to provide an explanation as to how we can still know reality as it is when we cannot experience or see the world as it is.

I'm not sure we can "know reality as it is".

Yet you are making all these claims about reality as it is. Am I to believe the claims you have made about reality?

huh?

To keep yourself from sliding down the slope into solipsism, you need to come up with an explanation as to how we can know about the world even though "we don't see the world as it is". — Harry Hindu

Since you are asking "how we can know about the world even though "we don't see the world as it is", I will assume you could not keep yourself from sliding, and so you believe solipsism is the case unless demonstrated otherwise.

Ok, if that is your belief, I think we need to get some things straight before we can converse about this topic.

1. Please do not address me as if I exist independent of your mind. According to you I am only an aspect of your mind/consciousness. As such, think of me as another voice in your head. Some psychiatrists would call this auditory hallucinations, but they do not know what they are talking about because they probably are unable to grasp these fundamental rigorous logical arguments about reality.

2. Please do not flirt with indirect realism and say the cause of me exists outside your mind/consciousness because then you are admitting there could be something more than just your mind/consciousness. Remember, I am part of your mind/consciousness.

3. Do listen to what anybody who says you might have a dissociative identity disorder or multiple personality disorder. Those folk don't understand the logical implications that we need to accept when Solipsism is the case. Remember, those folk are just parts of your mind/consciousness as well.

4. To think of it, what if I convinced you that I exist apart from your mind/consciousness, This sounds like I am a contradiction, both existing independent of your mind and dependent on your mind at the same time. And we know contradictions can't exist therefore I only exist as part of your mind. That said, I think I also proved that any argument that would convince you of the opposite could also not be formulated. So, you cannot be convinced to give up solipsism with logic either.

Yours truly, you.

Since you are asking "how we can know about the world even though "we don't see the world as it is", I will assume you could not keep yourself from sliding, and so you believe solipsism is the case unless demonstrated otherwise. — Richard B

I'm not a solipsist so the rest of your post is irrelevant. The fact that you did not answer the question is indicative that you do not have an answer yet you keep claiming that we do not see the world as it is, so my point was that YOU are the solipsist, not me.

To even attempt to answer the question, how about you start off by answering whether you experience your mind as it is or not.

Thats good, at least we both believe solipsism is a untenable position.

At least one of you does, anyway. (Or it might only be me.)

Thats good, at least we both believe solipsism is a untenable position. — Richard B

You made solipsism a tenable position by saying things like, "we don't see the world as it is". I'm now asking you how you can then say "solipsism is an untenable position" after saying "we don't see the world as it is". How can you be so sure there is even an external world if you can't trust what your senses are telling you? Do you even have senses?

[reply="Harry Hindu;987258"

I have not said “we don’t see the world as it is” in this post. I don't believe I have commented on this, that said, I can.

When someone uses such a phase, I think the onus should be on the asserter as what would the world look like “as is” vs “not as is”. They need to set up the contrast. Descartes demon may be able to perfectly duplicate a world, but runs into the problem of distinguishing between the two. Better yet why not say that we have more of the same world in that case.

In terms of trusting “senses”, you trust your senses until there is a reason not too. This reason is not to reach some abstract position of absolute certainty but to successful cope with the world around you.

When someone uses such a phase, I think the onus should be on the asserter as what would the world look like “as is” vs “not as is”. They need to set up the contrast. Descartes demon may be able to perfectly duplicate a world, but runs into the problem of distinguishing between the two. Better yet why not say that we have more of the same world in that case. — Richard B

Where would this duplicate world be relative to the original? It appears to me that the duplicate would be part of the greater reality that includes the original and duplicate, just as heaven and hell, along with the universe is all part of one reality as the events in one can affect the events in others.

If the duplicate mirrors the original, then it would be a world as well.

The problem appears to be a misuse of language more than anything else.

The issue isn't that our senses are wrong. An original table will look just like a duplicate table, even for the demon. The difference is our knowledge of another world - the original that we have yet to observe - that is lacking, not that our senses are lying to us.