Idealism: Other minds exist!
Solipsism: Other minds don't exist!

Idealism: Other minds exist! — Agent Smith

Prove it.

Solipsism: Other minds don't exist! — Agent Smith

Prove it.

Idealism is believing that reality needs minds in order to exist, solipsism is believing that only your own mind exists.
They differ in the implications of each of those beliefs.

I'd say both solipsism and idealism derive from a common observation: that I directly experience only my physical sense data, my emotions, and my thoughts. So, I experience shades of green and brown; the green patches feel smooth; the brown patches feel rough. The idea of a tree arises in my mind. I do not directly experience the tree.

Solipsism: that's all that exists. There is no tree. The tree is just an idea in my mind. Nothing exists outside of me. Matter is no more than a thought in my mind.

Idealism: something exists outside of me which causes my sense data. What is that something? Materialists say its matter. Berkeley says it is God causing my sense data but other idealist answers are possible.

Idealism: Other minds exist!
Solipsism: Other minds don't exist! — Agent Smith

A direct & succinct answer to the OP.

However, both are unprovable inferences from Descartes' intuitive introspective "I am" argument. From that axiom, we can a> optimistically reason that similar minds exist in the bodies of our fellow philosophers. Or, we can b> pessimistically conclude that nothing exists apart from my own inner world model.

Both can be argued for or against, but not proven empirically. Yet, according to b>, even empirical evidence could be a product of my own world-modeling mind. We know both possibilities, only by reading our own minds.

From personal experience though, my own intuition is not smart enough to make-up all the observed complexities of reality. So, I have to assume that those counter-intuitive ideas & opinions are coming from external minds with different life experiences. :cool:

My 2 drachmas:

By idealism I understand 'only minds and ideas (or what we is known) are real.' Ontology reduced to epistemology. (Related to 'antirealism', 'essentialism' (e.g. universals), immaterialism / nonphysicalism / supernaturalism, 'social constructionism', 'common sensism', 'moral subjectivism / relativism / nihilism', ''finalism', 'existentialism', metaphysical libertarianism, etc.)

By solipsism I understand 'only my mind and my ideas (or what I know) are real.' Ontology without epistemology. (Reductio ad absurdum of idealism)

All solipsism is a form of idealism, idealism need not be solipsist at all.

Solipsism posits that only I exist and that everything else - crucially - other people, are a product of my mind. When I die, everything vanishes: history, politics, art, etc.

Idealism is often presented as a phrase that should be obvious, and one should have strong opinions about it as soon as once hears the word.

Nevertheless, there's are many types of idealisms: some claim that only perceptions exist (Hoffman) , other claims that we can only see appearances, but that a world absent these exists (Kant), yet others posit that we are all part of one mind (Kastrup), or that something remains in the world which is not mental (Schopenhauer). And so on.

It often means that only ideas exist, or that the only thing we can know are ideas (Locke, Hume) or that mental stuff is fundamental, or that the only thing that counts as "real" are those things which trigger our innate dispositions (Descartes, Chomsky).

But idealism is much broader, and arguably richer, than solipsism, which varies mostly (if not exclusively) on intensity: only my life exists, only the past day exists, only the present moment exists, etc.

EDIT: I should mention, the philosophers listed may be argued to belong in other characterizations, this is a unsophisticated form of presenting versions of idealism.

Idealism and solipsism are derived from the simple fact that a world external to mind or self respectively can't be known to exist. As you can see, these philosophical stances are predicated on possibility (metaphysics) and agnoiological (epistemological) concerns.

A direct & succinct answer to the OP.

However, both are unprovable inferences from Descartes' intuitive introspective "I am" argument. From that axiom, we can a> optimistically reason that similar minds exist in the bodies of our fellow philosophers. Or, we can b> pessimistically conclude that nothing exists apart from my own inner world model.

Both can be argued for or against, but not proven empirically. Yet, according to b>, even empirical evidence could be a product of my own world-modeling mind. We know both possibilities, only by reading our own minds.

From personal experience though, my own intuition is not smart enough to make-up all the observed complexities of reality. So, I have to assume that those counter-intuitive ideas & opinions are coming from external minds with different life experiences. :cool: — Gnomon

:up:

Idealism and solipsism are derived from the simple fact that a world external to mind or self respectively can't be known to exist. As you can see, these philosophical stances are predicated on possibility (metaphysics) and agnoiological (epistemological) concerns. — Agent Smith

Prove it.

Prove it. — praxis

Idealism & Solipsism are possibilities and ergo all that needs to be proven is that they are...possibilities and that's as easy as ABC. Try it for yourself. Couldn't it be that the external world/other minds are mental projections?

They are representations. My mind models a representation of you, for instance.

They are representations. My mind models a representation of you, for instance. — praxis

And...does that somehow disprove the claim that it's possible the external world/other minds are mind-generated/mind- sustained?

If you were a figment of my imagination I would know more about you then you do. Do you think that I know more about you then you do? I don’t know the color of the shirt you’re currently wearing, assuming you’re wearing one. You most likely do.

If you were a figment of my imagination I would know more about you then you do. — praxis

Interesting. What if not knowing all is built into the grammar of solipsism or such figments? It is possible to imagine a voice without a body and then to put a body to that voice. Nothing is fully imagined or understood in dreams, let along in a potential solipsistic universe.

I get that - except isn't idealism a la berkeley predicated on the idea that all things disappear when we're not experiencing them first hand.

The tree in the forest - and me - and you?

In other words, the entire sense-excperience I'm having is in my head. Only my head. That's solipsism no?

I get that - except isn't idealism a la berkeley predicated on the idea that all things disappear when we're not experiencing them first hand.

The tree in the forest - and me - and you? — GLEN willows

No. Berkeley has everything or 'empirical reality' held in place by the mind of god who allows us to share a world which exists independent of our mental processes.

Idealism often has to make use of some kind of 'big mind' to prevent solipsism. For Kastrup - a current idealist - all matter is just what consciousness looks like when viewed from a different perspective. What allows us to share a world is that it is all held in place by a universal mind - cosmic consciousness or 'mind at large'. But this is not a god - this consciousness is instinctive, blind and striving and is not metacognitive. Humans are described as dissociated alters of this consciousness.

From Kastrup's blog:

Although I say that all reality is in consciousness, and that there is no universe outside, or independent from, subjective experience, I also do not deny that reality exists independent of personal psyches, like the human psyche. I maintain that empirical reality is an experience of an impersonal mind, which I like to call 'mind-at-large' in honor of Aldous Huxley. As such, empirical reality isn't created by personal psyches, and would still exist as an experience in mind-at-large even if there were no life in the universe.

Bernado Kastrup

If you were a figment of my imagination I would know more about you then you do. Do you think that I know more about you then you do? I don’t know the color of the shirt you’re currently wearing, assuming you’re wearing one. You most likely do. — praxis

I could counter your point but only with another that's rather far out! I concede your point! It's an interesting argument! Kudos.

I get that - except isn't idealism a la berkeley predicated on the idea that all things disappear when we're not experiencing them first hand.

The tree in the forest - and me - and you?

In other words, the entire sense-excperience I'm having is in my head. Only my head. That's solipsism no? — GLEN willows

As far as I can tell, idealism is either difficult or impossible to disprove. The same goes for solipsism. These philosophical positions rest on, as I said, possibilities that, as for now, can't be ruled out.

I guess that's my point - Berkeley "has to make use of some kind of 'big mind' to prevent solipsism." That or a cosmic consciousness, neither of which I take seriously because I've never seen any evidence of either.

So what's a skeptical atheist to do? I agree with Agent Smith that solipsism is impossible to disprove, but I notice it gets short shrift in philosophical circles. It seems like the "dead end" everyone is trying to avoid (Descartes only proved one mind / thinking thing....then ran to God for the rest.).

My point is - Solipsism is never treated as a legitimate theory compared to Empiricism or Idealism...not to mention Leibniz and his wacky "Monads." When to my mind most theories point to - or at least make a LOGICAL argument for - the lack of any world or minds outside our own. Especially when God and anything "cosmic" are taken out fo the argument.

I may start a group "Solipsism is Real" although it would have only one member.

Or better "Solipsist Unite."

So what's a skeptical atheist to do? I agree with Agent Smith that solipsism is impossible to disprove, but I notice it gets short shrift in philosophical circles. It seems like the "dead end" everyone is trying to avoid (Descartes only proved one mind / thinking thing....then ran to God for the rest.).

My point is - Solipsism is never treated as a legitimate theory compared to Empiricism or Idealism... — GLEN willows

It's an absurd position. The concepts of reason and truth are entangled with the concepts of self and other. The rationalists are right to the degree that they foreshadow the idea of a space of reasons as irreducible, but Descartes (for instance) was wrong to think he could have the concept of the self as something primary, something that makes sense apart from the concept of others. What is this 'I' ? Why is it automatically understood as a unity ? How does meaning work ? What counts as rational ? Does private rationality makes sense? Descartes is in one important sense not skeptical enough. But maybe the point was the math and the physics...

Yet idealism is prone to fall into solipsism.

Idealism holds that for a statement to be true it must stand in some relation to mind - observed, known, believed, or whatever. So is "There are other minds" true for idealism? If it is true, then it stands in some relation to mind... but which one? If it stands in a relation to a mind other than one's own, then that is profoundly problematic for idealism. Hence the need for god to hold things together.

Idealism's relation to truth is... incoherent.

Yes, idealism is prone to collapse, as you mention. The problem is maybe a hidden tautology, a language trap. In order for a statement to be true it must stand in some relation to mind .... stand in relation to language ... be a statement.

'Tell me about the world that no one can tell me about. See, it's impossible ! Henceforth idealism...'

As far as I can tell, idealism is either difficult or impossible to disprove. The same goes for solipsism. — Agent Smith

As I see it, some positions can be made to look incoherent or confused or indeterminate in the first place. I don't pretend that it's easy to get consensus on such matters, but I do think something outside the binary approaches of true/false and provable/unprovable deserves mention.

For instance, if the self is the only thing that can be verified, what are we to even make of the concept of self in play here ? How did the sense-data theory get invented or implanted in the first place? Why take it for granted, along with some unified entity, the self-world-blob ? It's like accepting $\sqrt{2}$ or even $\aleph_0$ without worries or objections but questioning the intelligibility of $-1$.

...Idealism often has to make use of some kind of 'big mind' to prevent solipsism...
...
From Kastrup's blog:
...
I also do not deny that reality exists independent of personal psyches, like the human psyche. I maintain that empirical reality is an experience of an impersonal mind, which I like to call 'mind-at-large' in honor of Aldous Huxley. — Tom Storm

Interesting that merely renaming this independent reality (godmind or whatever) is felt to be worth the trouble. I browsed Kastrup once, and he does write well, but it's hard to see more than language traps and mystically/religiously tinged (albeit pessimistic) usage preferences once one has been corrupted or disillusioned by the usual suspects (those dreary buzzkill linguistic philosophers and pragmatists.) For context, I don't feel strongly about 'matter' and the 'physical' either when used metaphysically or 'transpractically.' Perhaps I'm missing out. Too late now.

So what's a skeptical atheist to do? — GLEN willows

"Skeptical" of what? (Atheism?)

All solipsism is a form of idealism, idealism need not be solipsist at all. — Manuel

:up:

Idealism holds that for a statement to be true it must stand in some relation to mind - observed, known, believed, or whatever. So is "There are other minds" true for idealism? If it is true, then it stands in some relation to mind... but which one? If it stands in a relation to a mind other than one's own, then that is profoundly problematic for idealism. Hence the need for god to hold things together.

Idealism's relation to truth is... incoherent. — Banno

:fire:

For context, I don't feel strongly about 'matter' and the 'physical' either when used metaphysically or 'transpractically.' Perhaps I'm missing out. Too late now. — Pie

You and me both, Pie. I've written here before that even if idealism is true, it makes no difference to how I live my life. A perfect illusion of a material world which can't really be transcended except perhaps via glimmers during meditation, or perhaps at 'death', is functionally no different to an actual material world. The speeding bus coming at you will still end your plans even if it is the product of mentation seen from a particular perspective. So why should all this matter, except as a curiosity? Fascinating though it may be.

A perfect illusion of a material world which can't really be transcended except perhaps via glimmers during meditation, or perhaps at 'death', is functionally no different to an actual material world. — Tom Storm

Well put, Mr. Storm, and you touch on another pet issue of mine with the word 'actual' and its synonym 'real.' In practical life it's great. I want real money or real love or real science and not the counterfeit kind. But away from every familiar context the real/illusion dichotomy loses traction, fails to distinguish the better from the worse.

Nothing is fully imagined or understood in dreams, let along in a potential solipsistic universe. — Tom Storm

True, however, my dreams are entirely comprised of elements that I know or have experienced. I can't dream understanding the language of Japanese, for instance. I could dream about walking on the moon, I imagine, but it wouldn't be anything like Neil Armstrong's moon dreams. It would probably play out like a dumb episode of Space:1999. My dreams tend to be really dumb.