How do I know that this piece of paper still exists when I put it away in my desk and leave the room? — PossibleAaran

Because you haven't given a reason to motivate believing existence or persistence is dependent upon perception. — MindForged

Does knowledge require certainty or just (strong) justification? If the former then you might not be able to know. — Michael

perhaps it's more reasonable to believe that if things are found where they're left then they were there all along than to believe that they "pop" into and out of existence when you look. — Michael

Why is it more reasonable to believe that things exist unperceived than that they pop into existence? — PossibleAaran

I believe that there are items which exist — PossibleAaran

So? Lacking a reason to think that Not-P is not a reliable means of establishing that P. It isn't a reliable method of establishing anything.

Perhaps parsimony? — Michael

would be would it matter? Or is it just a matter of intellectual interest? — Michael

Is there something out there in the fabric of the universe? Probably yes.

But what is it until Mind perceives it? That is the question. — Rich

If that is the case, to give any reason to believe they do not exist when unperceived, don't you need to establish some causal relation between perception on one hand, and existence (or at least persistence) on the other? Otherwise it just looks like an arbitrary speculation. — MindForged

Is there anything at all when the mind isn't perceiving? That is the question I am asking. If your answer is 'probably yes', why do you say that? — PossibleAaran

But I never attempted to prove that things don't exist unperceived, so I don't need to establish any causal relation between perception and existence. I asked whether there is any way that I can know that things do exist when unperceived. I haven't speculated at all. Simply raised a question.

During one's life, one is always perceiving new things as one develops skills in perception. — Rich

Other life forms are reacting to things we do not perceive. — Rich

Well I can raise a question about any old thing I want. Perhaps mathematical truths are only true when a conscious being considers their truth value. But as with your "simple question", unless there is a reason to motivate considering the question as being true or at least plausible, it seems like idle speculation. And that you seem to accept that objects exist when perceive would entail some kind of relationship between existence and perception if we wish to raise a question about if they exist unperceived. — MindForged

The fact that you exist necessarily implies that everything that is outside you exists since it is something that is not you, and hence it is. The same applies to everything that you can perceive. That is, the fact that a paper sheet exists, which you are able to prove through your sense-perception, implies that everything outside the limits of the paper sheet exists, for what is outside the paper sheet is not the paper sheet, and thus it is. — Daniel

Therefore, even if you stop perceiving the paper sheet, what is not the paper sheet, ie. you and everything else that is not you or the paper sheet, by existing, causes the paper sheet to maintain its state of existence, for the paper sheet can only be that, a paper sheet. If it were the case that as soon as you stoped perceiving an object it would stop existing or it would exist in some other way, the change in the state of existence of the object would necessarily cause a change in your state of existence and in the state of existence of everything you are now perceiving. However, because this is not the case, it is same to assume that the contrary is what is real. Let me know what you think. — Daniel

The first thing to note is that questions aren't true or false, plausible or implausible. Only propositions are, as I've always understood the words 'true' and 'plausible'. Second, the question I raise is hardly ridiculous. Is there any reliable way to tell that things exist when unperceived? If there isn't, then the belief that things exist unperceived is sheer guess work. The question itself isn't the idle speculation. Rather, a failure to answer the question shows that the belief in unperceived existence is idle speculation.

Lastly, yes, I agree that some objects exist when perceived. Hold up a piece of paper in front of your face. There is something that exists at the moment when you are perceiving it. But that doesn't settle the question of whether it exists unperceived.

Perceiving them gives evidence that the objects at least existed at that time. — MindForged

But does it therefore mean that not perceiving them lends justification to the idea that they don't exist otherwise? — MindForged

No it doesn't, and I would never make this inference. That is, the fact that an object, O, exists when perceived by me does not entail that O does not exist when unperceived. The former does not even make it likely that O does not exist when unperceived. So, I am not assuming that 'perception brings a thing into existence'. I am not assuming the opposite either.

But even given this, there is still a further question about whether O exists unperceived or not. Either it does or it doesn't, and the fact that it exists when perceived doesn't entail that it also exists unperceived. It might be, for all we have said so far, that O exists when I perceive it but the moment I stop perceiving it, it ceases to exist. I am not assuming that this is true, and so I am not 'idly speculating'. What I am saying is that this has not been ruled out by anything we have said so far. You have not suggested any reliable method by which we could determine whether something exists when unperceived. You have suggested that some things exist while they are being perceived, and I have agreed with you on that. You then seem to think that somehow it just follows that they exist when unperceived as well. It does not follow, unless there is some reliable way to establish that these things don't just disappear from the world when unperceived.

You'd have to be assuming that because otherwise there's no reason to suggest they do not exist when not perceived. If we know an object, O, exists when perceived, we know it at least existed. If you question its persistence sans-perception, the only way that can be the case is if perception causes existence. I don't see how you're not assuming that; it's the only possible way for the contrary to be true (unless things just happen randomly, I suppose). — MindForged

the only way that can be the case is if perception causes existence. I don't see how you're not assuming that; it's the only possible way for the contrary to be true (unless things just happen randomly, I suppose). — MindForged

We justified believing "O" exists by our perception, we didn't justify the notion that "O" exists only when we perceived it. — MindForged

there seems to be no grounds from which to raise the idea that the object stops existing when unperceived. — MindForged

'Everyone knows that the earth, and a fortiori the universe, existed for a long time before there were any living beings, and therefore any perceiving subjects. But according to Kant ... that is impossible.'

Schopenhauer's defence of Kant on this score was [that] the objector has not understood to the very bottom the Kantian demonstration that time is one of the forms of our sensibility. The earth, say, as it was before there was life, is a field of empirical enquiry in which we have come to know a great deal; its reality is no more being denied than is the reality of perceived objects in the same room.

The point is, the whole of the empirical world in space and time is the creation of our understanding, which apprehends all the objects of empirical knowledge within it as being in some part of that space and at some part of that time: and this is as true of the earth before there was life as it is of the pen I am now holding a few inches in front of my face and seeing slightly out of focus as it moves across the paper.

This, incidentally, illustrates a difficulty in the way of understanding which transcendental idealism has permanently to contend with: the assumptions of 'the inborn realism which arises from the original disposition of the intellect' enter unawares into the way in which the statements of transcendental idealism are understood.

Such realistic assumptions so pervade our normal use of concepts that the claims of transcendental idealism disclose their own non-absurdity only after difficult consideration, whereas criticisms of them at first appear cogent which on examination are seen to rest on confusion. We have to raise almost impossibly deep levels of presupposition in our own thinking and imagination to the level of self-consciousness before we are able to achieve a critical awareness of all our realistic assumptions, and thus achieve an understanding of transcendental idealism which is untainted by them.

How do I know that this piece of paper still exists when I put it away in my desk and leave the room? — PossibleAaran

The trusty old Samuel Johnson refutation. — Wayfarer

What about the hypothesis that God causes O to exist and when I look away, God destroys O? What about the hypothesis that it is a law of nature that whenever we look in a certain place, O is created, and whenever we look away, O is destroyed? — PossibleAaran

It might be, for all we have said so far, that O exists when I perceive it but the moment I stop perceiving it, it ceases to exist. I am not assuming that this is true, and so I am not 'idly speculating'. What I am saying is that this has not been ruled out by anything we have said so far. You have not suggested any reliable method by which we could determine whether something exists when unperceived. — PossibleAaran

This is compatible with everything ceasing to exist when no one is perceiving it, so how does this support the view that things exist unperceived? — PossibleAaran

How can this be known? How do you know that there are other life forms when you are not perceiving them? — PossibleAaran

Is it coherent to say that you can have a perception of small part of the world without the rest of it existing to support it, including the body that's doing the perceiving?

Can I have a visual perception while my eyes don't exist (because nobody's perceiving them)? I don't actually see my eyes when I'm looking, unless there's a reflecting surface. — Marchesk

How do I know that this piece of paper still exists when I put it away in my desk and leave the room? — PossibleAaran

But for those who haven't been 'through the looking glass', the question can only be dealt with from the perspective of scientific realism. — Wayfarer