The point in this question is not the Moon, but the word ËXIST".

If no one is looking at the Moon, the word ËXIST' has no meaning. Hence the Moon has no meaning either in that case.

Is it true that the moon does not exist if nobody is looking at it?
No.
Next!

Not much of a philosophical argument. As for Corvus

If no one is looking at the Moon, the word ËXIST' has no meaning. Hence the Moon has no meaning either in that case.

, that's not much of an argument either, although at least it has a premise and a conclusion, even if it's not clear how they are related to each other. In any case, Corvus is right that the point isn't just about our moon, it's about existence in general, and whether things that are not actually being perceived exist or not. Occidental commonsense screams "of course they do", but what passes for commonsense in the West might not be true (I started another discussion on this point 'Commonsense versus physics').

that's not much of an argument — jkg20

An empty claim requires no argument.

You are misunderstanding what observation even meant. An observation can occur without any conscious or living being present. Basically, new-agers routinely misuse quantum mechanics to support all sorts of gibberish. For one thing, since Einstein came up with relativity, and even before then regarding transforms, we can't even say that we are "observing" the moon any more than we can say that the moon is "observing" us, since space is not absolute. That should give anyone a hint that the discussion was not talking about consciousness being necessary in order for a material world exist.

I only see the surface of the same side when I look at the moon, what are you guys looking at? I might as well ask if what's below the surface of the Earth actually exists because I don't look at it. Does my brain exist, heart, lungs, bones, etc? I've never witnessed a thought, even a philosophical one. For all these things I just mentioned, I see no better than the blind, who always seem to be omitted from this type of discussion. It's as if believing something doesn't exist because it can't be observed requires some faith....now there's a switch.

Let's just call the moon a cosmological constant.

> For all these things I just mentioned, I see no better than the blind

For some reason, vision is often abused in philosophy as the stand-in for all perception and observation. Thing is that vision works differently than smell, where you're inhaling pieces of the thing itself.

> I only see the surface of the same side when I look at the moon, what are you guys looking at? I might as well ask if what's below the surface of the Earth actually exists because I don't look at it. Does my brain exist, heart, lungs, bones, etc

Indirect observation has been brought up several times in this thread. The moon's gravitational influence continues when we're not looking at it, and our bodies do all the body-things like pumping blood, breathing and digesting (or having thoughts) while we're not looking inside.

I take that as evidence that a naive form of idealism is no more tenable than naive realism.

All this reminds me of the old (Oxford?) rhyme, which I recreate from momory:

'There was a young man who said, 'God,
Don't you find it exceedingly odd,
That that very large tree
Simply ceases to be
When there's no-one around in the Quod?'

To which, quite relaxedly, God
Said 'Nothing about it is odd,
And that very large tree
Never ceases to be -
I am always around in the Quod'.

Sorry about spelling and punctuation above - as a trained typist and an old English teacher I sufferwith this keyboard!

God in the Quad by Ronald Knox ( Balliol Oxford)

There was a young man who said "God
Must find it exceedingly odd
To think that the tree
Should continue to be
When there's no one about in the quad."

Reply:
"Dear Sir: Your astonishment's odd;
I am always about in the quad.
And that's why the tree
Will continue to be
Since observed by, Yours faithfully, God."

This is the version I am familiar with. The sentiment is the same and Knox captures well Berkeley's concern, unsurprising as a theologian to have a role for God in the sustaining of the Universe. An earlier contributor is quite right to bring in quantum mechanics where the issue of non measurement comes to the fore as having an influence on events.

o have a role for God in the sustaining of the Universe. An earlier contributor is quite right to bring in quantum mechanics where the issue of non measurement comes to the fore as having an influence on events. — Edmund

Can a supernatural being perform a measurement? Is God collapsing the universal wave function to this universe, allowing us to evolve?

Quantum mechanics is at best irrelevant to the idealism v materialism debate, and at worse just invites obscurantism and confusion. A materialist interpretation of quantum mechanics is possible, as is an idealist one. Einstein's question apparently was addressed to those early QM theorists who leaned towards an idealist interpretation, but interpretations of QM have moved on since the days when the so-called "Copenhagen" and "Hidden Variable" interpretations were the only games in town.

I think the kind of idealism that Berkeley propounded is best argued for by investigating the basic metaphysical assumptions behind the relational view of perception - @jkg20's post earlier in this discussion pinpoints the basic assumptions, but to develop a full blown argument out of them takes a lot of time (believe me, I've tried) and involves dealing with issues concerning nominalism v realism about properties , personal identity over time, adverbialism and representationalsim in the philosophy of mind, to name just a few. Whether you can have Berkelian idealism without also requiring God to be around in the quad is an interesting question.

If nobody ever observed the Moon, then there'd be no proof it exists. Either the moon exists or it doesn't. Without proof, you'd be unable to prove it's existence or nonexistence. The existence of the Moon would be unknown. Things need scientific evidence to be proven, while people's beliefs aren't always accurate. For example, when I feel confident I got 100% on a test, but I actually gave some incorrect answers.

Quantum mechanics is at best irrelevant to the idealism v materialism debate, and at worse just invites obscurantism and confusion.

Take a look at the Kastrup thread - plenty of confusion and some obscurantism, doesn't help that QM purloined the term "observer".
Anyway, I'm interested in what you say about proving idealism by analysing perception - have you read John Foster? He attempts to argue for idealism entirely indepentently of the usual kind of arguments from illusion and hallucination.
By the way, any relation between you and MetaphyicsNow.com, or is that just coincidence ?

An observation can occur without any conscious or living being present. — LD Saunders

How so? If a spacecraft hurtles out past Neptune, all instruments intact, busily registering lots of data which will never be transmitted to Earth, does any of that amount to 'an observation'? It would seem not, according to the definition. (It is true that the Wikipedia definition says that 'In science, observation can also involve the recording of data via the use of scientific instruments' however, scientific instruments are explicitly created by scientists to capture data for observation, so whether the registration of data by an instrument amounts to an observation is still, I think, moot.)

For one thing, since Einstein came up with relativity, and even before then regarding transforms, we can't even say that we are "observing" the moon any more than we can say that the moon is "observing" us, since space is not absolute. That should give anyone a hint that the discussion was not talking about consciousness being necessary in order for a material world exist. — LD Saunders

So why do you think it was necessary for Einstein to raise the hypothetical question 'does the moon continue to exist when we're not looking at it?'

A materialist interpretation of quantum mechanics is possible, as is an idealist one. — MetaphysicsNow

Any examples?

Whether you can have Berkelian idealism without also requiring God to be around in the quad is an interesting question. — MetaphysicsNow

We definitely have posters who have argued for subjective idealism without utilizing God, even saying that God was the flaw in Berkley's philosophy.

dealing with issues concerning nominalism v realism about properties , personal identity over time, adverbialism and representationalsim in the philosophy of mind, to name just a few. — MetaphysicsNow

Sounds interesting. I've wondered if there is a way to resolve fundamental metaphysical disputes with that sort of approach where you bring in the various related issues and try to tie them all together.

A materialist interpretation of quantum mechanics is possible, as is an idealist one. — MetaphysicsNow


Any examples?

For a materialist interpretation - Wheeler's "many worlds" comes to mind. The Von Neumann-Wigner interpretation is often cited as an idealistic one, but I've always suspected it of being more dualistic. For something more recent, you can take a look at
https://janszafranski.wordpress.com/2015/08/05/the-idealistic-interpretation-of-quantum-mechanics/
I think there's some philsophical confusion going on in the paper (to be expected of a scientist) but there's a theoretical physicist doing their best to formulate an idealistic interpretation.

I don't think fundamental metaphysical disputes will ever be resolved :wink: Having said that, I share your opinion that you cannot even attempt to resolve them piecemeal - which is unfortunately the way that modern analytic philosophy tends to favour.

Anyway, I'm interested in what you say about proving idealism by analysing perception - have you read John Foster? He attempts to argue for idealism entirely indepentently of the usual kind of arguments from illusion and hallucination.

I have heard of, but not read, Foster. As far as I am aware his basic argument is epistemological in nature, and the problem with that (at least insofar as analytic philosophy is concerned, a tradition to which he belongs) is that the standard position in analytic philosophy is that you cannot obtain a metaphysical conclusion from epistemological premises. In fact, that same principle is what causes the arguments from illusion and hallucination to be given pretty short shrift these days.

By the way, any relation between you and MetaphyicsNow.com, or is that just coincidence ?

Not a coincidence!

We definitely have posters who have argued for subjective idealism without utilizing God, even saying that God was the flaw in Berkley's philosophy.

As I see it, phenomenalistic/subjective idealism faces three challenges:
1) Avoid the collapse to solipsism
2) Account for the apparent permance of particulars
3) Account for the apparent fact that numerically distinct people can perceive one and the same thing in different ways (i.e. from different perspectives).

I'm not sure one can meet those challenges and remain an phenomenalist idealist without supposing there to be a God, but I'm also not sure you can even meet those challenges by supposing there to be a God.

Wheeler's "many worlds" comes to mind. — MetaphysicsNow

Wheeler did not originate the ‘Many worlds’ thesis. That was the work of his graduate student, Hugh Everett III - here- , although the term ‘many worlds’ was the work of a later researcher, Bryce DeWitt. Wheeler insisted that Everett tone down the thesis considerably, including removing all references to ‘splitting’. [As is explained in that article, Everett left academia disillusioned and instead worked for the military-industrial complex designing re-entry paths for ICBM warheads.]

The term ‘consciousness causes collapse’ has unfortunate connotations. Consciousness is not a ‘cause’ in the sense of a causal factor, on par with a spark causing an explosion. The reason that 'consciousness causes the collapse' is because:

'What answer we get depends on the question we put, the experiment we arrange, the registering device we choose'.

'Consciousness causes collapse' only in the sense that the performing of the measurement determines the kind of outcome. Of course the fact that an experiment produces an outcome is normally not an issue. The conundrum here is that, prior to this act of measurement, there is no particle, but only the probability of there being one; when the observation is made, hey presto! there's a particle. And in this case the object of this experiment is supposed to be a fundamental constituent of reality. So that's why it's a conundrum - and hence also Einstein’s question.

OK, but bear in mind that many worlds interpretations effectively deny that there is any such thing as the collapse of the wave equation at all. Materialist interpretations of QM will take issue with your statement

prior to this act of measurement, there is no particle, but only the probability of there being one

Under materialist interpretations there is always a particle, prior to, during and after measurement.

Thanks for putting me right about Knox, Edmund. I didn't do badly as a creative imitator thought, fair play!

Under materialist interpretations there is always a particle, prior to, during and after measurement. — MetaphysicsNow

I haven’t heard of any such interpretations. The many worlds interpretation doesn’t say that, but it’s not worth debating, as it can’t be resolved one way or the other.

As I see it, phenomenalistic/subjective idealism faces three challenges:
1) Avoid the collapse to solipsism
2) Account for the apparent permance of particulars
3) Account for the apparent fact that numerically distinct people can perceive one and the same thing in different ways (i.e. from different perspectives). — MetaphysicsNow

I hadn't thought of number two. Regarding #1, idealists had attempted to dismiss it with the claim that idealism includes other minds from the start. The problem there is epistemological. How do they know about the other minds? And that leads to a justification issue. You can't just define other minds into existence and call that good.

I've seen at least one hard core idealist admit that #3 was a challenge. I don't recall seeing mention of #2, but it's definitely an issue. I think there were claims that each perception was a separate particular, and there was no permanence. Problem being that we do perceive objects persisting.

Regarding 1, granted it depends on how one argues for idealism, but simply to include other minds from the start smells of avoiding the difficult issues. Berkeley has a number of arguments, but if any of them are admitted as sound the metaphysical conclusion is at most that there is my mind and one other non-limited mind (to account for the fact that the world is recalcitrant to my will). Simply asserting that one's ontology includes other minds in that context is just to avoid the question, not to address it. A popular line of thought is the tu quoque response that materialist's have just as much of a problem as idealist's with establishing the existence of other minds.
With regard to 2, it is the apparent permanence of particulars (e.g. whenever I look into the clear night sky, I see the moon) that leads Berkeley to suppose that there must be a God that sustains the existence of the moon when no limited mind is looking at it. That may or may not work - God's perceptual relation to the moon probably has to be very different from ours when we look at it. More recent phenomenalists (some of the logical positivists for instance) tended to talk instead of "the moon" just being a term that ultimately unpacks as a set of conditional statements to the effect that "if person X were to look in direction y at time t, then person X would have an experience as of a moon being in the sky". The problem with this "moon as the permanent possibility of sensation" response is that it is natural to suppose that there is something that accounts for the truth of those conditional statements, and what is that something other than the continued existence of the moon when it is not being looked at?
As for (3), I think this is probably the most difficult issue for phenomenalistic idealism to address - I don't have much sensible to say about it at the moment, but it is something I am mulling over.

I haven’t heard of any such interpretations. The many worlds interpretation doesn’t say that, but it’s not worth debating, as it can’t be resolved one way or the other.

The many world's interpretation is, at root, just the idea that the wave function quantifies over all actual and possible states of affairs, where those actual and possible states of affairs are ultimately actual and possible arrangements of electrons and other elementary particles. Hence it is fully committed to the existence of particles before after and during any experimental measurements. It denies any interpretation of QM that involves the idea that the wave function collapses at any point. It has an ontology (at least in many of its forms) that commits it to possibilia as well as actualities, but that might be the price to pay for maintaining materialism.
Anyway, as you say, this is not really the thread in which to discuss interpretations of QM.

Not a coincidence!

So when we will get this promised proof of God's existence then?

Hence it is fully committed to the existence of particles before after and during any experimental measurements. — MetaphysicsNow

I get that, but at the cost of there being many worlds. The MWI advocates here on this forum seem to obfuscate that inconvenient fact.

The question I always ask is: if you're prepared to entertain such a fantastic idea, then what problem are you actually solving? If indeed 'desperate problems call for desperate remedies' - then what's the problem? What do you have to admit, if you let go of MWI?

I get that, but at the cost of there being many worlds.

True, but then for some people that is more palatable than idealism. Incidently, there was at least one recent philosopher (David Lewis, whose ideas are still quite influential in so-called analytic philosophy) who had a range of arguments independent of QM interpretation for the real existence of possible worlds. So even that issue is independent of the whole QM debate.