Going by idealism, and keeping it consistent, there’s no difference among you and my experiences of you. — jorndoe

I think is a bit of a misinterpretation, although an understandable one. But Kant's 'refutation of idealism', in the second edition of the Critique of Pure Reason, addresses this exact criticism, in the context of showing what was wrong with Berkeley's account.

I am certainly one of the idealists here, but I also believe, with Kant, in the model of 'empirical realism, transcendental idealism'. The upshot, for me, is that the mind makes an inextricable contribution to knowledge. We can't see or know anything as it is, or as it would be if it were not being observed by any mind. Knowledge is of appearances, and appearances imply a subject. It doesn't mean empiricism is untrue, but it does mean that empiricism will never have the final word.

@Wayfarer, so the Moon and I exists independently of your perception thereof?

• the perception is not always the perceived (Searle and others)
• my experience of you is not you (non-solipsism)
• the experience is not always the experienced (non-idealism)

There's a trap in your question. What does 'independent' mean? 'There anyway', right? We know the moon and the earth pre-date h. sapiens by billions of years, it doesn't make any sense to say they exist only in the minds of humans. But the subtle question is this one - what is it, that provides the perspective of 'before' such and such an event, and the units in which the measurement of that duration is made? Where does that judgement reside?

We have a scientific account of the existence of the world prior to our personal existence, and it is consistent with many kinds of evidence that it indeed pre-existed us. But all of that evidence is still something that requires interpretation and explanation by a subject, in order to be brought to bear on the question at hand. So the sense in which that pre-existing world is independently real can still, I think, be called into question. But that is also not to say that it is merely or only subjective, in the sense of pertaining only to my understanding. It is part of the shared understanding of our culture and indeed species. But it is still an understanding, in that an essential component of it is a cognitive act of interpretation.

Recall it was Einstein who rhetorically posed the question: does the moon continue to exist when we're not looking at it? He was genuinely perplexed, and also somewhat indignant, that such a question need be asked. But what caused him to ask it, was the so-called 'measurement problem' which had become apparent in the very field of science of which he was a pioneer, namely, quantum physics. The discoveries of Bohr and others threw Einstein's rock-solid assumption of the 'mind-independence' of reality into doubt. And that is why he asked that very question; he devoted many of his Princeton years to attempting to overturn the apparently idealist implications of physics. This, by the way, is documented in two thoroughly researched books, Manjit Kumar's Quantum and David Lindley's Uncertainty. Both of these refer to the 'battle' over scientific realism, for 'the soul of science' or over 'the nature of reality'.

What you're up against, is a consequence of a foundational move in the Enlightenment, which was to cast aside metaphysics, and to see the world as it truly is, shorn of 'metaphysical baggage'. However, as has become clear, it was not nearly so straightforward; philosophy, as Etienne Gilson remarked, has a remarkable ability to 'bury its undertakers', i.e. those who have declared it dead.

I was talking to an Indonesian the other day, who told me that in the Indonesian language there is no verb 'to be'. That appears to make it a real-life version of David Bourland's invented language E-prime, which is English with that verb and all synonyms removed.

The relevance of that to the thread is that, without that verb, I don't think one can even describe a difference between an Idealist and a materialist. The difference dissolves to just one of language use.

Bourland was a student of Korzybski. Wiki says that Korzybski agreed with his student to the extent that he thought two uses of the verb 'to be' - those of identity and predication - had structural problems. It confuses me no end that Korzybski is best known for his saying 'The map is not the territory', which uses 'to be' in the 'identity' use. So according to Korzybski himself, his most famous utterance may be meaningless.

What do you take it that idealism (or at least the form of it you want to question) is saying?

It certainly seems that whatever reality "in itself" 'is', it is independent of your mind or my mind. If it is independent of all human minds, (as would certainly seem to follow) then what mind could it be dependent upon?

Berkeley's answer is "God's mind". Unless God or a universal mind is posited, then it would seem that reality cannot be mind-dependent.

Kant's answer is that the empirical is real (meaning tangible or available to the senses) and the transcendental (the conditions for the possibility of experience ) is ideal. But what does "ideal" mean in that transcendental context? Kant denies Berkeley's notion that what is transcendental is dependent on Gods' mind, and instead posits that it is mediated by the human mind to give rise to experience. Can this mean that the transcendental is originated by the human mind? I don't believe that to say that could make any sense at all. So, if the transcendental (in its origin) is independent of any and all human minds; then it would not seem right to refer to it as ideal. It (whatever it is) must, on that account, be real (in fact it must be the ultimate reality), so the position 'transcendental idealism' really makes only very limited sense.

'The map is not the territory', which uses 'to be' in the 'identity' use. So according to Korzybski himself, his most famous utterance may be meaningless. — andrewk

There's other ways of noting that a map of London is not the city of London. I can't hail a cab while visiting a map of London. I can't bungee jump off a six inch model of the Eiffel Tower. And the equations of gravity written out on a chalkboard don't exert any force on me.

Of course the map isn't the territory.

The relevance of that to the thread is that, without that verb, I don't think one can even describe a difference between an Idealist and a materialist. The difference dissolves to just one of language use. — andrewk

Does it really though? If you asked this Indonesian tribe whether imaginary rocks are made up out of the same stuff as ordinary ones you stump your toe on, would they say yes?

Yes, what we perceive is only perceived though the mind. We cannot know what a thing in itself is as it is, we can only know it as we experience it. Some say that we can't even think a thing in itself, unlike Kant. But the idealist must recognize a world, and must agree that the world could be otherwise than it is, that what is, is only contingent, as proven by our own mortality.

If you asked this Indonesian tribe whether imaginary rocks are made up out of the same stuff as ordinary ones you stump your toe on, would they say yes? — Marchesk

The imaginary vs real distinction doesn't relate to the question of Idealism vs Materialism. Both Idealists and Materialists make the imaginary vs real distinction.

It's not some obscure tribe by the way. It's the official language of Indonesia, spoken by more than 200 million people.

I suppose if I wanted to ask an Indonesian, in Indonesian, whether Harry Potter is real, I might ask something like 'Do you think anybody ever did all those things that the book says Harry Potter did?'.

Of course the map isn't the territory. — Marchesk

The question is though, given Korzybski's concerns about the use of 'is' in the 'identity' sense (concerns that presumably arose later in his life, subsequent to his making the famous statement), how would he have rephrased that statement?

Perhaps something like:

'A map does not have all the same properties as the territory it represents'

Are you forgetting about objective idealism, @jorndoe? To believe that all things are mental or immaterial is not to say that all things are my experiences.

And consider the Cartesian dualist who believes that there are physical bodies and minds. Now just take away the physical bodies. There are minds other than mine. It's idealism, but not solipsism.

You're only considering solipsistic idealism. But obviously solipsistic idealism entails solipsism.

I suppose if I wanted to ask an Indonesian, in Indonesian, whether Harry Potter is real, I might ask something like 'Do you think anybody ever did all those things that the book says Harry Potter did?'. — andrewk

We could also ask the Indonesian if rocks are made up of smaller things we can't see, taste, touch, etc which give the rock the properties it has.

There are minds other than mine. It's idealism, but not solipsism. — Michael

I never understood how idealism justified this stance. I get that metaphysically non-solipsistic idealists maintain there are other minds, but how they know this is problematic.

Now just take away the physical bodies. There are minds other than mine. It's idealism, but not solipsism. — Michael

So me perceiving your body is how I know you have a mind? *Ahem*

I never understood how idealism justified this stance. I get that metaphysically non-solipsistic idealists maintain there are other minds, but how they know this is problematic. — Marchesk

How does the materialist know that there are other minds?

So me perceiving your body is how I know you have a mind? *Ahem*

Yes. Isn't that also what the materialist says?

Yes. Isn't that also what the materialist says? — Michael

Yes, bodies are more than perceptions for a materialist.

How does the materialist know that there are other minds? — Michael

This depends on whether the materialist can make a case for mind being a part of a living body. If so, then the materialist can say that we perceive the activity of a mind when interacting with another human being.

The idealist doesn't have this option, since bodies are just ideas. Minds can't be ideas on the pain of solipsism.

If so, then the materialist can say that we perceive the activity of a mind when interacting with another human being. — Marchesk

And the idealist says the same. Only that the human beings that we interact with are mental/immaterial things, not physical/material things.

And the idealist says the same. Only that the human beings that we interact with are mental/immaterial things, not physical/immaterial things. — Michael

That doesn't work, because minds aren't ideas. See where I edited my previous post right before you responded.

It's not some obscure tribe by the way. It's the official language of Indonesia, spoken by more than 200 million people. — andrewk

My fault, read too quickly. Used to hearing about some tribe that thinks/does things radically different.

Anyway, for what it's worth, I used Google Translate from the English "to be or not to be" to Indonesian: "untuk menjadi atau tidak menjadi". Then reversed it, and "to be or not to be" was the result.

I tried "existence" => "adanya" => उपस्थिति (hindi) => presence

That's interesting. उपस्थिति => Kehadiran => presence

I wonder why the Indonesian to Hindi is different.

That doesn't work, because minds aren't ideas. — Marchesk

So? You have some straw-man understanding of idealism.

The idealist claim that all things are fundamentally mental or immaterial in nature is not to say that only my experiences exist. And the idealist's claim that independent minds can interact with and perceive each other is no more problematic than the physicalist's claim that independent bodies can interact with and perceive each other.

The idealist claim that all things are fundamentally mental or immaterial in nature is not to say that only my experiences exist. — Michael

Yeah, I know that.

And the idealist's claim that independent minds can interact with and perceive each other is no more problematic than the physicalist's claim that independent bodies can interact with and perceive each other. — Michael

But I don't see how. Walk me through how I go from ideas of your body in my mind to interacting with and perceiving your mind, which isn't an idea/perception at all.

But I don't see how. Walk me through how I go from ideas of your body in my mind to interacting and perceiving your mind, which isn't an idea/perception at all. — Marchesk

You're a mental thing and I'm a mental thing. When we "touch" this elicits in you certain experiences.

It's the same sort of thing that happens for the materialist. When my physical body "touches" your physical body, this elicits in you certain experiences.

You're a mental thing and I'm a mental thing. When we "touch" this elicits in you certain experiences. — Michael

So our minds touch? Or is it our perceptions that are touching?

It's the same sort of thing that happens for the materialist. When my physical body "touches" your physical body, this elicits in you certain experiences. — Michael

I don't think it is. Materialism does have difficulties with incorporating all aspects of mind, but not in this case. Having a body is how we interact.

Having a body is how we interact. — Marchesk

And the idealist would agree. It's just that our body is a mental/immaterial thing, not a physical/material thing.

If we go for Hume's bundle theory, for example, our bodies are bundles of sense-data, and when these bundles of sense-data interact, you can directly perceive my immaterial body (as per a naive/direct realist understanding of perception).

If we go for Hume's bundle theory, for example, our bodies are bundles of sense-data, and when these bundles of sense-data interact, you can directly perceive my immaterial body (as per a naive realist understanding of perception). — Michael

The problem here is that sense-data are sense-data for some perceiver, not an independent bundle that anyone can perceive. Unless you want to invoke God as the universal perceiver, there is no place for an independent bundle of bodily sense-data.

There is a huge epistemological hurdle to overcome here where mind A and mind B are somehow having a shared sense-data experience, where mind A's is of mind B's sense-data body bundle, and vice versa.

Come to think of it, why would mind A & B have sense-data body bundles at all?

The problem here is that sense-data are sense-data for some perceiver, not an independent bundle that anyone can perceive. Unless you want to invoke God as the universal perceiver, there is no place for an independent bundle of bodily sense-data. — Marchesk

But this is what (some) idealists claim is the case. So you're saying that idealism can't avoid solipsism because non-solipsistic idealism is false?

If all you want to do is argue that idealism is wrong, then fine. But it's still the case that there are forms of idealism that don't entail solipsism; that claim that the fundamental nature of the world is mental/immaterial, but that my mind is just one small part of a much bigger world (which contains other minds).

But this is what (some) idealists claim is the case. So you're saying that idealism can't avoid solipsism because non-solipsistic idealism is false? — Michael

I don't know. It seems like it has an epistemological problem regarding other minds.

As an analogy, say both of us are BIVs. I have experiences of a world and people, and so do you. Let's say you're aware of being envatted. Now how would you know that I exist, and solipsism isn't the case for you? You would have to say that somehow we interact. But in order for that to happen, something has to wire our BIVs together in order to have a shared experience. So we can invoke the mad scientist as an analogy for Berkley's God.

But without the mad scientist, there's no reason to think that my experiences have anything to do with any other minds, other than as pure speculation. There's no way for me to know if my experience of you is anything more than an idea in my mind.

Materialism suffers from the same epistemological problem.

Materialism suffers from the same epistemological problem. — Michael

A materialist can say that it's inconceivable for a human being to act like they have a mind but not have one, since mind is necessary for human behavior.

A materialist can say that it's inconceivable for a human being to act like they have a mind but not have one, since mind is necessary for human behavior. — Marchesk

And the idealist can say the same.

And the idealist says the same. Only that the human beings that we interact with are mental/immaterial things, not physical/material things. — Michael

Then why don't I experience your mind instead of your body when we touch?

Are our minds touching when I read your words on this screen? How is that different than being in each other's presence? I can experience you as words on a screen, or as a body, or as a voice on the phone, but never as a mind.

When I look in a mirror, I don't experience a reflection of my mind. I experience a reflection of my body.

And the idealist can say the same. — Michael

Materialism suffers from the same epistemological problem. — Michael

And the idealist would agree. — Michael

So then what is the difference between materialism and idealism? Why choose one over the other?

It seems to me that you are saying that we aren't disagreeing on which meat we are chewing on, rather we are chewing on the same meat and we are merely disagreeing on the name of the meat we are chewing on.

If all you want to do is argue that idealism is wrong, then fine. But it's still the case that there are forms of idealism that don't entail solipsism; that claim that the fundamental nature of the world is mental/immaterial, but that my mind is just one small part of a much bigger world (which contains other minds). — Michael

What is it that separates other minds, if not time and space, for us to say that there are other minds besides my own? What is it that causes us to experience other bodies, and not other minds, when we "touch"?