To be is to be perceived. I perceive a rock, so it exists. But it doesn't exist outside being perceive. I perceive you so, so you exist, at least while I'm perceiving you. — Marchesk

That doesn't follow. "To be is to be perceived" is not the same as "to be is to be perceived by me". The rock doesn't require that I perceive it. It exists if someone perceives it.

So other minds (perceiving themselves) is consistent with "to be is to be perceived".

That doesn't follow. "To be is to be perceived" is not the same as "to be is to be perceived by me". The rock doesn't require that I perceive it. — Michael

But my knowledge of other minds comes from perception, just like my knowledge of rocks. So there is a skeptical problem for the idealist that the solipsist recognizes, and the idealist pretends isn't an issue.

Furthermore, the idealist doesn't even perceive the other minds, just their bodies. The other mind is a mental inference. It's an ontological commitment the solipsist would never feel warranted in making.

But my knowledge of other minds comes from perception, just like my knowledge of rocks. So there is a skeptical problem for the idealist that the solipsist recognizes, and the idealist pretends isn't an issue. — Marchesk

What's the sceptical problem?

Furthermore, the idealist doesn't even perceive the other minds, just their bodies. The other mind is a mental inference.

Of course, But it's a mental inference that (according to the idealist) can't be used to infer the existence of some non-mental substance.

What's the sceptical problem? — Michael

I perceive a rock. I perceive you talking about having perceived a rock when I wasn't around. I create a mental model of you perceiving stuff in my absence.

The skeptical problem is how I can know you actually exist outside my mental model when I'm not perceiving you. The idealist solution is just to assert that of course other minds are around perceiving when I'm not perceiving them. Solipsism avoided. But it's just an assertion. There is no sound epistemological basis for that assertion.

The skeptical problem is how I can know you actually exist outside my mental model when I'm not perceiving you. The idealist solution is just to assert that of course other minds are around perceiving when I'm not perceiving them. Solipsism avoided. But it's just an assertion. There is no sound epistemological basis for that assertion. — Marchesk

As you say, it's an inference; the same one that the materialist uses. The idealist just rejects the claim that one can use this reasoning to infer the existence of some non-mental substance from which objects are made and which exists even when nobody is perceiving it. This proposed substance is, to the idealist, as unintelligible as magic or the soul. Although we understand thoughts and experiences and so can make some sense of such things happening independently of us, we don't really have any understanding of the so-called "physical" (our imagining of such things is actually imagining the (disembodied) experience of things), and so claims of such a thing are actually meaningless.

To be is to be perceived. I perceive a rock, so it exists. But it doesn't exist outside being perceive. I perceive you so you exist, at least while I'm perceiving you. — Marchesk

To be is to be apprehended with the intellect, not to be perceived by the senses. There is a big difference here. I understand with my mind, that other minds exist. I do not perceive other minds with my senses. However, I do apprehend that there is a separation between my mind and other minds, and I need my senses to navigate this separation. But real being is what lies beyond this separation, that which can only be apprehended with the mind.

Re the conversation about idealism, I agree that idealists are not necessarily solipsists, but I do not agree that it's easy to make sense out of non-solipsistic idealism, or rather, that it's not easy to present a version of idealism where non-solipsistic views seem justified.

If one believes that only mental phenomena occur, it's difficult to figure how one could know that any mental phenomena are not simply one's own, or how one could be justified in claiming that any mental phenomena are not simply one's own. This goes just as well for people who assert ontological realism but who are something like representationalists on philosophy of perception, or in other words, who at least pay lip-service to ontological realism but who are effectively epistemological idealists.

Of course, some versions of idealism are looser stances where folks are simply emphasizing the importance of ideas. Those are a different issue. Those stances are not making exhaustive ontological inventory claims.

Of course, some versions of idealism are looser stances where folks are simply emphasizing the importance of ideas. Those are a different issue. Those stances are not making exhaustive ontological inventory claims. — Terrapin Station

Classical idealism assigns priority, or a higher level of reality, to the realm of ideas than to the realm of material existence. You might consider that idealism and materialism both developed as forms of dualism. As dualisms, they would each accept the reality of both ideas and matter. However, idealism would assign priority to ideas, claiming that Forms are a necessary condition for material existence, and materialism would assign priority to matter, saying that matter is a necessary condition for the existence of ideas.

It is only under the modern trend toward monism, which attempts to simplify things, that a materialist might dismiss the reality of ideas altogether, or some forms of solipsistic idealism might attempt to dismiss material existence altogether. It should be quite evident that monism is the cause of these problems, not idealism or materialism per se. So to choose monism over dualism, as a way to avoid the question of which is prior, matter or Forms, is a mistaken choice.

If a tree falls in the forest, and nobody is around, does it still make a sound? — dukkha

What do you mean by "making a sound"? Do you mean it produces a sound "quale" or do you mean it generates a "sound" as defined in physics (i.e. pressure wave within the air)?

I think it's actually just a rhetorical question.

You can't equate idealism with solipsism. As we've gone over many times before, they're not the same thing. The idealist's position is that all things are mental in nature; it's not simply the position that all things are a product of one's own mind. There can be other minds, each with their own thoughts and experiences, that continue to exist even when you're dead. — Michael

OK, so your explanation of idealism is that idealism is actually realism in that things continue to exist even when no mind is accessing it via the senses. It's just that the primary substance is mental rather than physical. Is every realist then a materialist or physicalist? Your definition seems to make idealism into realism with the only difference being the what the primary substance of reality is (and does this even matter the label we use in naming the primary substance if it follows scientific laws?)

So if everything is mental and can exist without senses accessing them, then does that equate to direct realism or indirect realism? The problem with this is why do I experience your text on a screen and not your mind if everything is mental? Does your posts exhaust everything about your mind? When I read your posts, am I reading your mind?

You only experience other bodies, or their text that they type, and then infer that these bodies and text are evidence of other minds. You never experience other minds directly.

What about when you look in a mirror? Why is it that you don't see your own mind? Why do you see a body?

OK, so your explanation of idealism is that idealism is actually realism in that things continue to exist even when no mind is accessing it via the senses. It's just that the primary substance is mental rather than physical. Is every realist then a materialist or physicalist? Your definition seems to make idealism into realism with the only difference being the what the primary substance of reality is (and does this even matter the label we use in naming the primary substance if it follows scientific laws?) — Harry Hindu

That's objective idealism, yes. But that's not what I meant. What I meant is that the (non-objective and non-solipsistic) idealist can accept that only minds exist without having to accept that only one's own mind exists. So you exist and I exist and seven billion other people exist, all with our own independent thoughts and experiences (but which are able to causally influence one another), but that a material world of trees and rocks does not exist independently of anyone experiencing them.

What about when you look in a mirror? Why is it that you don't see your own mind? Why do you see a body?

Seeing a body is just the occurrence of mental phenomena. It's a bundle of qualia that is then interpreted as being a single object (in the same sort of way that the materialist will say that a bundle of subatomic particles is interpreted as being a single object).

That doesn't follow. "To be is to be perceived" is not the same as "to be is to be perceived by me". The rock doesn't require that I perceive it. It exists if someone perceives it. — Michael

You do not know any perception other than yours. You can at least see rocks, you can't see other perceptions; so if you conclude that things only exist in so far as they are perceived, and you only know your own perception then you should conclude that rocks exist and perceptions other than your own do not.

This thread has now been duplicated, courtesy of Marchesk.

That's objective idealism, yes. But that's not what I meant. What I meant is that the (non-objective and non-solipsistic) idealist can accept that only minds exist without having to accept that only one's own mind exists. So you exist and I exist and seven billion other people exist, all with our own independent thoughts and experiences (but which are able to causally influence one another), but that a material world of trees and rocks does not exist independently of anyone experiencing them. — Michael

So then what is the medium in which these other minds exist? To say that other minds exist implies a separation of minds. What is it that divides minds apart from each other? What exists between minds if not a shared world? By using the term, "other", you automatically imply the existence of some medium that separates them.

Seeing a body is just the occurrence of mental phenomena. It's a bundle of qualia that is then interpreted as being a single object (in the same sort of way that the materialist will say that a bundle of subatomic particles is interpreted as being a single object). — Michael

My point was that you don't see other minds, only other bodies.

My point was that you don't see other minds, only other bodies. — Harry Hindu

And my point is that it doesn't matter. I don't need to see other minds for there to be other minds. The idealist's claim isn't simply "only the things I see exist". Rather it's "only mental phenomena exists", with us seeing bodies being the occurrence of a particular type of mental phenomena.

By using the term, "other", you automatically imply the existence of some medium that separates them.

No I don't. That one thing is not another thing does not require some third thing to separate them. Else what fourth thing separates this third thing from the first two things? And so on.

And my point is that it doesn't matter. I don't need to see other minds for there to be other minds. The idealist's claim isn't simply "only the things I see exist". Rather it's "only mental phenomena exists", with us seeing bodies being the occurrence of a particular type of mental phenomena. — Michael

Then you don't need to see other trees for there to be other trees. This is why the idealist is inconsistent until he follows his own arguments where they lead - to solipsism.

The only mental phenomenon you have access to is your own. How do you know that other mental phenomenon exists besides yours? And then how is your answer not also applicable to other things, like trees and forests?

No I don't. That one thing is not another thing does not require some third thing to separate them. Else what fourth thing separates this third thing from the first two things? And so on. — Michael

Like I said, use of the term, "other" implies the existence of something to separate these things. If I don't use the term "other" in describing a world, then I'm not implying a 4th thing to separate worlds. It is you using the term other to describe minds. No one has used the term, "other" to describe worlds. If they did then they'd have to explain what it is that separates worlds. But no one has, so your point is ridiculous.

This thread has now been duplicated, courtesy of Marchesk. — Wayfarer

Sorry, I wanted to explore the implications of what you posted in it's own thread. It always struck me as the strongest objection to realism. Didn't mean it to be explicitly about the tree.

Oh don't worry, it's just that it then gets hard to remember which thread is which! But, photons are cheap. X-)

Oh don't worry, it's just that it then gets hard to remember which thread is which! But, photons are cheap. — Wayfarer

Is the photon from a distant star one minute away not yet perceived real, or only conceptual until we perceive it?

Hang on, I have an absolute bottler of an article about that very thing.....

http://discovermagazine.com/2002/jun/featuniverse

No realist discussion is complete without mention of QM, eh?

I'll read it here in a minute. Wheeler is also the physicist who proposed it from bit, I believe.

Is the photon from a distant star one minute away not yet perceived real, or only conceptual until we perceive it? — Marchesk

Do you mean lie was the cosmic microwave background real before we predicted it, planned to look for it, but discovered it by accident anyway?

As soon as you get into Schrodinger's Cat territory, threads collapse into a Black Hole from which no intelligence ever emerges.

http://discovermagazine.com/2002/jun/featuniverse — Wayfarer

So Wheeler proposes a delayed choice double slit experiment using photons from a distant quasar with gravitational lensing involved by galaxies in between. Very interesting.

Question though, what if alien minds existed in that distant quasar. Does that change the outcome?

At least Wheeler allows for inanimate detectors to decide quantum outcomes. Lindren goes all the way to conscious observers only determining the history of the universe. What distinquishes us from the cat in the box? If ancient aliens have put Earth inside a box, perhaps with a quantum object that has a 50/50 chance of turning into a black hole that consumes Earth, are we in a state of destroyed/not destoryed before they look?

They're all beyond my pay grade. But that article gives a pretty good account of some of the conundrums:

Wheeler conjectures we are part of a universe that is a work in progress; we are tiny patches of the universe looking at itself — and building itself. It's not only the future that is still undetermined but the past as well. And by peering back into time, even all the way back to the Big Bang, our present observations select one out of many possible quantum histories for the universe.

What strikes me, is the adjective 'tiny'. Sure, we're physically 'tiny' - but we're also that 'patch of the universe' that actually can weigh and measure the universe! Only we know how 'tiny' we are, but we only know that because we know what 'big' means!

All of these things are the source of bamboozlement. Feynmann said something like 'don't ask how it can be that way, it simply is that way, and if you ask why you will fall into a hole that nobody has ever gotten out of.' And that's true. The only moral I take from the whole story is that scientific or transcendental realism is likely not to pan out. It's a useful attitude for scientists and engineers, but don't mistake it for a metaphysic.

Then you don't need to see other trees for there to be other trees. — Harry Hindu

The idealist doesn't claim otherwise. They just claim that trees need to be seen for there to be trees. It doesn't require that I'm the one doing the seeing. For the umpteenth time, there's a difference between "to be is to be perceived" and "to be is to be perceived by me".

The only mental phenomenon you have access to is your own. How do you know that other mental phenomenon exists besides yours?

It's an inference; the same inference that the materialist makes.

And then how is your answer not also applicable to other things, like trees and forests?

For the same reason that the materialist's answer isn't applicable to other things like magic or souls or eldritch abominations. That there's evidence for other minds is not prima facie that there's evidence for something else, i.e. a non-mental substance that constitutes a world of objects that exists independently of anyone seeing them.

We can make sense of other minds because we have our own thoughts and experiences. But this supposed non-mental physical substance is actually a vacuous concept, as evidenced by the fact that when trying to imagine a physical thing we just imagine the (disembodied) experience of such a thing.

The idealist doesn't claim otherwise. They just claim that trees need to be seen for there to be trees. It doesn't require that I'm the one doing the seeing. For the umpteenth time, there's a difference between "to be is to be perceived" and "to be is to be perceived by me". — Michael

And for the umpteenth time, there needs to be a consistent shared world for you to mean anything when you use the term, "other", or else there isn't other minds, only one mind.

How is it that we both experience the same tree from different perspectives (I can see your eyes looking in the same direction as mine and we both agree that there is a tree.) Where does your post on this forum reside when no one is reading it? How does it keep it's spelling, grammar and meaning when no one is looking at it for these things to appear when someone does read it? There must be some way that your post exists and maintains its properties for me to read it and understand what you are attempting to communicate.

For the same reason that the materialist's answer isn't applicable to other things like magic or souls or eldritch abominations. That there's evidence for other minds is not prima facie that there's evidence for something else, i.e. a non-mental substance that constitutes a world of objects that exists independently of anyone seeing them. — Michael

There must be something else because I don't direct access to your mind. There is some barrier preventing me from accessing your mind. I can only access it indirectly through your posts or seeing your person. Again, for me to believe there are other minds means I must also believe in something separating them that isn't a mind.

The idealist doesn't claim otherwise. They just claim that trees need to be seen for there to be trees. It doesn't require that I'm the one doing the seeing. For the umpteenth time, there's a difference between "to be is to be perceived" and "to be is to be perceived by me". — Michael

Will a camera suffice, or does it need to be a human.

It needs to be a mental phenomena.