you said that because this entails believing contradictory things, the objection fails. — Michael

You're ignoring my conditional. I said that IF the mere conceivability or possibility of a claim is sufficient for believing that claim, then it would require believing contradictories for the vast majority if claims.

You're not making sense. Would you care to explain? — jkop

Sorry... "In the dream, you asserted P." is true IFF in the dream, you asserted P.

Did I assert P in the dream? Yes, I did.

Problem?

You're ignoring my conditional. I said that IF the mere conceivability or possibility of a claim is sufficient for believing that claim, then it would require believing contradictories for the vast majority if claims. — Terrapin Station

Then as I said, it doesn't address the objection, which is that realism isn't justified because there are grounds to doubt it – which is not the same as claiming that realism is false.

Problem? — Mongrel

Yes, do you mean that the existence of dreams, or dreams of saying things, would somehow show that we never know whether we dream or not?

Yes, do you mean that the existence of dreams, or dreams of saying things, would somehow show that we never know whether we dream or not? — jkop

I asked how you know you aren't dreaming right now. What does it suggest.. that you don't simply answer the question?

When I said you could fly off the table; what I meant is something like that you could levitate of of it, even if it is the living room. I suppose you could fly off a table if it was outside and you were wearing a 'jetpack' or something like that.

A real table can turn into something else; a pile of wood perhaps, but if it is a wooden table it cannot turn into something which is not wooden, short of a Biblical scale miracle. A dream table, on the other hand, could turn into a fish, an elephant, or a troupe of buffoons.

The interesting thing about dreaming is that it only during lucid dreaming, that is when you know in the dream that it is a dream that you can control the dream and do anything, and go any where, you wish. Or so, I am led to believe.

As to how I know i am not dreaming now; I would say that it is because I can remember so much detail about the last couple hours and how what I did during that time relates to what I did yesterday and the rest of my life as I remember it. i do not remember having that kind of experience of sustained memory and meaning in dreams. We must be able to make at least some meaningful distinction between waking and dreams, even to be able to ask the question.

Then as I said, it doesn't address the objection, which is that realism isn't justified because there are grounds to doubt it — Michael

I explicitly said in my comment that the initial post presents no grounds beyond conceivability/possibility.

I don't imagine I have anything to teach you about Descartes' scenario. If we differ in our take on it, maybe it's a difference in what we think the conclusion is? I take Descartes at his word (I'm always confused and astonished by people who don't). He was looking at what can be doubted and what can't be. The Dream argument is just part of the pondering.

I would say that it is because I can remember so much detail about the last couple hours — John

Do you really remember a lot of detail about the last couple of hours? I know people vary when it comes to that.

We must be able to make at least some meaningful distinction between waking and dreams, even to be able to ask the question — John

Right. My application of Leibniz Law was partly as a lark. The conclusion of the argument is not that there is no distinction (anymore than the one about the Evil Demon is concluding that there is an evil demon.)

I asked how you know you aren't dreaming right now. — Mongrel

Since I perceive the world directly there is no reason for me to doubt whether my experiences right now when I'm awake might be real or dreams.

What does it suggest.. that you don't simply answer the question? — Mongrel

No, after your clarification your question turned out to be easy to dismiss (despite your misuse of "logic").

OK

I can remember quite a bit of detail if I make the effort.

I don't think we are actually disagreeing about anything, just looking from the different available angles.

:P

3. Mind and world are ontologically dichotomous, with experience being entirely "internal" to the mind (e.g. qualia, ideas, representations, etc.) and the world being entirely "external" to it. — Aaron R

I wonder if this is something the dream argument needs to work. On the surface I would say no. Supposing there is no ontological dichotomy between mind and world, the mere possibility that we are in a dream seems to be enough to make the argument get off the ground. In fact, if we conclude skepticism on these grounds, it would seem to be consistent to simply not have an opinion on the matter.

One problem with the argument is that dreams are epistemically distinguishable from waking experience, in that they do differ quite a bit from waking experience. It's just that usually our ability to judge is suspended while dreaming, although not always. In lucid dreaming, we do realize we're having a dream, and can take control of it to some extent. It's not like we go to sleep and experience another life just like the one we're having, such that we can't tell which is the real life upon waking. Dreams often don't make sense, they're jumbled up and weird. They don't follow the rules of waking perception. — Marchesk

I used to argue exactly this, but I think it's a mistake in reasoning. We can distinguish between dream and reality, but what this does not do is provide justification for concluding that I know the ball I'm holding exists independently of my mind. Rather, all we are doing when we distinguish between dream and reality is setting how we use the terms "dream" and "reality" -- and applying a lack of coherence to the former and more coherence and rules to the latter. But could it not be the case that there are two types of dreams?

All the dream argument does is show that we are, in some cases, mistaken about how we use "reality" -- in what we term dreams we mistakenly believe they are real. So it is possible to believe something is real when it is not real, even by the mere definition of the terms set forth above. Hence, we have a reason to doubt, and therefore do not know. (via the argument, at least).

Following the appropriation, only if a person were unable to distinguish between dreaming and non-dreaming would they have grounds to doubt. But, not being able to know when they were in a dream state, they would not have reason to believe that they were ever in a dream! In fact, they would not even know what a dream was - even if you tried to explain it to them (like trying to explain blue to a blind man).

EDIT : After re-reading this, I realized that it might not be clear as to what I was trying to say.

Conclusion : The act of dreaming can never be used as grounds for doubting existence-sans-minds. Either we know the difference between dreaming and non-dreaming and could not logically use dreaming to disprove something about non-dreaming or, we do not know what a dream is and cannot hold it up as evidence for doubt. — Real Gone Cat

I suppose that would depend on how we cash out the terms "grounds for doubt" -- it would seem strange, I think, if a skeptic claimed to know, and on the basis of that knowledge then claimed to have grounds for doubt. The skeptic would claim that they do not know what a dream is -- but we have examples of being wrong about knowing when to appropriately use the word "reality" or "existence". Surely I know how to speak, hence our speaking. But that knowledge does not grant me reality, at least as far as we usually understand reality to not be defined by our speaking.

I agree, I have looked at all the arguments for doubt on a philosophy guide website and none of seem relevant to me. They merely discuss differences between the reality of a dream and the reality of waking experience, which for me are irrelevant and don't seem to address Descarte's doubt about sitting in front of the fire.

My perspective is in reference to being and the fact that due to some unknown process beings find themselves either in a dream, or in waking life, or perhaps in some other place such as as a ghost, or in some kind of heaven, or another world. Beings with minds just find themselves somewhere and be there.

Another way of saying this is that if solipsism is logically consistent (which I think it is), then a solipsist is in the same condition as this being I describe. They find themselves in a place, or state, through some unknown process and at some point will find themselves in another place and be there.

The problem is that if I am actually dreaming when I think I am awake, then all the characters that I interact with in my waking life have no conscious experience. Say it is true, as usually believed, that in my dreams the other characters are my purely own creations, and hence do not have any inner experience, then if it were also true in my waking life, this would amount to solipsism, pure and simple. And we all know that solipsism cannot be disproven, but that it is a very silly position to hold for obvious reasons.

Accept the consistency of solipsism and sufficient doubt is introduced for the OP.
Regarding the issue of other minds, in some sense we are all one mind(all the biosphere on Earth). So it may not be an issue atall.

Yes, it's true there is that 'universal mind' interpretation of solipsism, but it is very different to the solipsism that says that the only consciousness that exists is my own.

Quite.

I don't think the argument from the OP leads to solipsism. Looking at it again:

Klein, in his SEP article on skepticism, contends that the Dream argument conforms to the following schema:

1. If I know that p, then there are no genuine grounds for doubting that p.
2. U is a genuine ground for doubting that p.
3. Therefore, I do not know that p. — Aaron R

1. If I know that the object I am holding in my hand exists independently of my mind, then there are no genuine grounds for doubting it.
2. If I were now dreaming, then there would be ground for doubting that the object in my hand exists independently of my mind.
3. Therefore, I don't know that the ball in my hand exists independently of my mind. — Aaron R

Support for P2 being that a dream is not distinguishable from existence, in that we attribute reality to the dream while in a dream, but not when out of the dream.

The power of the dream scenario has more to do with how total it is, I think. When you are in a dream and you do not realize that it is a dream, then literally everything you experience is what, on this side of the dream, we would term not real. And, as @mcdoodle pointed out, we don't even have to term that side of the dream as not real -- we can actually term either side as "real" or "not real". There is a sense in which we've made a decision about reality in order to separate the real from the not real prior to the dream argument. And since what is in a dream seems total, and we've certainly thought that a dream was real before (and hence everything we experience, which we believe to be not real, is believed to be real) -- and so "U" -- we have a genuine ground for doubting p, and hence do not know that everything I experience is real.

But just because I do not know this that does not then imply, because of the character of "U", that I am a solipsist. If I am a skeptic, I would not be a solipsist in the sense that I would not claim to know that I am the only existing entity.

But just because I do not know this that does not then imply, because of the character of "U", that I am a solipsist. If I am a skeptic, I would not be a solipsist in the sense that I would not claim to know that I am the only existing entity. — Moliere

That's true. Soft solipsism says 'for all I know I am the only existing entity' rather than 'I am the only existing entity'. My point was only that if what we call waking life is really a dream, then it seems to inexorably follow that I am the only existing entity.

But then I would say you haven't responded to the skeptical argument. The skeptic isn't saying "for all I know I am the only existing entity", even -- but rather using the dream scenario as the "U" in the syllogism, rather than making a claim about reality at all.

And if that's the case, then your reductio ad solipsism wouldn't apply to the argument.

But the argument goes "If I were now dreamingg, then there would be ground for doubting..." Everything hinges on that "if"; so it is not given as a general ground for doubt that the object in my hand exits independently of my mind, but as a ground for doubt only in the specific context "I am dreaming".

Also, I might agree that the skeptic is saying something even weaker than "for all I know I am the only existing entity"; she might be saying: " I don't know that I am not the only existing entity". She might be saying this on the grounds that she believes that in the context of her dreams she is, as the dreamer, that is as the creator of all the entities she encounters there, the only existing entity. So, she believes that in the context of the world of the dream at least, solipsism is true. So if waking life is really nothing more than a dream, then solipsism would apply there also just as it is believed to in the dream context..

Granted Aaron R's rendition does say "if I were now dreaming"

I've been making a weaker claim, though. A genuine ground for doubting comes about merely because we choose what we count as real and what we count as not-real, first (how to use the words "dream" and "reality"), and then we have experienced being completely wrong about everything we experience (in what we term "dream" we have believed everything we experience is what we term "reality"), in accordance with how we choose to use those words. If that be the case then we could be completely wrong, once again. Therefore it is possible that I am in dream. That doesn't mean that I am in a dream, only that the possibility is there. The possibility, as I understand the argument at least, is enough to give "genuine grounds for doubting" -- at least as the skeptic has it.

Since the skeptic -- as I am rendering the argument -- is not making a claim about whether or not she is in a dream, much less what that dream is (solipsistic), it's just not the case that you can reduce her position to solipsism, as that is making a claim about reality.

I think you're still misunderstanding my point. I'm not claiming that skepticism can be equated with solipsism; I'm simply pointing out that to say that it might be the case that I am dreaming amounts to saying that it might be the case that I am the only entity, given that in the context of dream I am commonly understood to be the only entity. But you could be skeptical about that too, and say that in dreams I might be interacting with independently real entities, and not, as I usually think. with my own mental creations. But if you thought that then the possibility that I am now dreaming would be no ground in any context for doubting the independent existence of the entities I am encountering.

But what if you thought neither?

I think that's where the disconnect is. The skeptic doesn't believe either that we are in a dream or that there are independently existing entities. Rather, the skeptic points out that as we have been wrong, entirely, before, we could be wrong again -- and this is just in reference to common uses of the terms, so "being wrong" does not contain an ontological commitment. Hence, due to the possibility of error, we have a reason to doubt.

I do have difficulty coming to terms with the idea that doubting something could be coherent, unless I have a clear idea of what it is that I am doubting. So, if there were no clear idea about what the ontological statuses of waking life and dreams were, then there would be nothing to doubt. Then, I wouldn't call such a state 'being in doubt' but rather 'abiding in acceptance of mystery'. That would be quite congenial to me.
:)