An electron is a posit?

The argument from illusion is an argument for the existence of sense-data. It is posed as a criticism of direct realism. Naturally occurring illusions best illustrate the argument's points, a notable example concerning a stick: I have a stick, which appears to me to be straight, but when I hold it underwater it seems to bend and distort. I know that the stick is straight and that its apparent flexibility is as a result of seeing it through the water, yet I cannot change the mental image I have of the stick as being bent. Since the stick is not in fact bent its appearance can be described as an illusion. Rather than directly perceiving the stick, which would entail our seeing it as it truly is, we must instead perceive it indirectly, via a sense-datum. This mental representation does not tell us anything about the stick's true properties, which remain inaccessible to us.

With this being the case, however, how can we be said to be certain of the stick's initial straightness? If all we perceive is sense-data then the stick's apparent initial straightness is just as likely to be false as its half-submerged bent appearance. Therefore, the argument runs, we can never gain any knowledge about the stick, as we only ever perceive a sense-datum, and not the stick itself.

When we see the sun, our perceptual state is the result of how the sun was eight minutes ago. The sun might not even exist now; yet we would still be seeing exactly what we are seeing. So what we are seeing cannot be identical with the sun.

We do not experience electrons directly, in that we know they exist inferentially, through their "traces".

Laboratory instruments are capable of containing and observing individual electrons

Before we go farther it will be well to consider for a moment what it is that we have discovered so far. It has appeared that, if we take any common object of the sort that is supposed to be known by the senses, what the senses immediately tell us is not the truth about the object as it is apart from us, but only the truth about certain sense-data which, so far as we can see, depend upon the relations between us and the object. Thus what we directly see and feel is merely 'appearance', which we believe to be a sign of some 'reality' behind. But if the reality is not what appears, have we any means of knowing whether there is any reality at all? And if so, have we any means of finding out what it is like?

I'm sure there's more to these arguments than what I've humored. So, please, anyone, show me the light. Show me the good argument for believing we do not directly observe things, and that we cannot know the true properties of things. As of yet, I am unconvinced.

I did not maintain that these were sound arguments. On the contrary. But they are the kind of arguments that have been advanced for indirect or representative realism. They (or arguments like them) certainly persuaded philosophers like Descartes, Hume, Kant, A.J. Ayer, and many others that we cannot and do not observe the world directly, and, so, that there is an "external" world is an inference, and that there is an "external" world requires proof. G.E. Moore in the first line his famous essay, "Proof of an External World" cites Kant as writing that it is a scandal to philosophy that no one has ever proved the existence of an external world.

If all these intelligent minds think, or thought, this, then I must be missing something.

Why would Moore say such a thing? As far as I am concerned, the proof is all around us. I wonder what sort of proof he was looking for.

It makes absolutely no sense to me how one can, in the same breathe, state that a dozen people agree about the color and shape of a table, admit those people are seeing the same table, and then deny that an external world exists. No matter if they are perceiving the table differently, doesn't it seem reasonable that there is a table, and that the table is real? I don't see the reason in believing otherwise. I don't see a good reason to doubt.

If all these intelligent minds think, or thought, this, then I must be missing something.

Why would Moore say such a thing? As far as I am concerned, the proof is all around us. I wonder what sort of proof he was looking for.

It makes absolutely no sense to me how one can, in the same breathe, state that a dozen people agree about the color and shape of a table, admit those people are seeing the same table, and then deny that an external world exists. No matter if they are perceiving the table differently, doesn't it seem reasonable that there is a table, and that the table is real? I don't see the reason in believing otherwise. I don't see a good reason to doubt.

If all these intelligent minds think, or thought, this, then I must be missing something.

Why would Moore say such a thing? As far as I am concerned, the proof is all around us. I wonder what sort of proof he was looking for.

It makes absolutely no sense to me how one can, in the same breathe, state that a dozen people agree about the color and shape of a table, admit those people are seeing the same table, and then deny that an external world exists. No matter if they are perceiving the table differently, doesn't it seem reasonable that there is a table, and that the table is real? I don't see the reason in believing otherwise. I don't see a good reason to doubt.

It's the room for doubt that's the problem. It isn't necessarily a denial that an external world exists, only an admittance of the possibility, and that possibility has been shown in many examples, the classics being Descartes's.

So the can of worms is that we could be misled about all of the intuitive ways that we try to justify things, and if that is the case then nothing is justified. So saying it isn't reasonable would be no longer justified.

I didn't say that Moore said that. I said that Moore quoted Kant as saying that. In his essay "Proof of an External World" he attempts to prove just what Kant said it was a "scandal to philosophy" that it has not been proved.

No one of those people who expressed reasons for skepticism denied that there is an external world. Descartes, Kant, and the others believed there was an external world, and, in various ways, tried to overcome the argument from illusion and other skeptical arguments. David Hume famously wrote that he believed there was an external world, but that it could not be proved that there is, and Hume thought that we ought ask not whether there is an external world, but why we believe there is an external world. And he thought that was because we cannot help believing there is an external world. That it is an instinctual belief.

In general (although there may be disagreement about this) I think that the doubt that there is an external world is justified by these philosophers because they hold that it would be possible for us to have all of the evidence we now have for an external world, and yet that there be no external world.

I don't think Descartes' example (evil demon) shows that there might be no external world. We may just ask where this demon is? In the external world of course. Everything that is, is in the external world which is the same as the world.

I think D. example showed that the world might be very different than it is, that we might not have bodies but only minds/brains.

Descartes' demon is just a literary device for making the point. The point is, however, that we might have all the evidence we now have for an external world, and yet, there might not be an external world. (The same goes for Putnam's "brain in vat"). Why would that be self-contradictory? Something like that happens when we are dreaming. (Which, of course, is still another argument).

I don't think Descartes' example (evil demon) shows that there might be no external world. We may just ask where this demon is? In the external world of course. Everything that is, is in the external world which is the same as the world.

I think D. example showed that the world might be very different than it is, that we might not have bodies but only minds/brains.

---------- Post added 02-15-2010 at 06:10 PM ----------



Can anyone describe a scenario where we have all our current evidence (in particular our sense-data) and there is no (external) world? If so, please do so. I can't imagine a non-contradictory description.

If existence is random and independent, then existence could randomly be internal, "all in your head".

If our reasoning behind justification is void then anything could be true.

Another useful (much more useful than the above) example is the phantom arm, where if you lose a limb you still feel as if it is there. Just imagine a phantom world where all of your senses are produced by your mind for your mind.

Where is brain in a vat?

Where is the mind? Does the mind exist? If yes, then it exists in the external world. If it does, then there is an external world... See above.

Who knows? But it is just another literary device.

I don't like it either. But its failure does not show that it is not possible that we have all the evidence that we now have, and there be no external world.

Forget the literary devices which may fail for the reason you give. Is it self-contradictory that we have all the evidence for an external world we do have, and that there be no external world?

Then what would be your definition of a non-external world? Is the distinction not usually placed with the assumption of the physical?

What R. claimed is that we do not experience tables or any of the other objects we usually talk about as examples in any strictly speaking direct sense. What we experience are sensations that these objects cause us to have.

It's the room for doubt that's the problem. It isn't necessarily a denial that an external world exists, only an admittance of the possibility, and that possibility has been shown in many examples, the classics being Descartes's.

I don't know what "non-external world" means. This is why I wrote earlier that I consider "external world" to refer to the same thing as "world" does.

The room for doubt is not the problem. In fact, it isn't a problem at all. You can doubt all you like, but if there's no good reason to doubt, no rational person will listen.

But that's exactly the point... if what we consider rational is really arbitrary, then "there's no good reason to doubt" holds no water.

So the admittance of the possibility is more of a humbling factor than anything else, and that is important to me for the sake of trying to understand other people's views.

Alright. But then I have still not seen a coherent description of a scenario where we have all our current evidence but there is no external world. I'm inclined to think all such scenarios are self-contradictory.



That's right.



Where is all this evidence that we have and where are we? In the external world? Do we exist? If not, then what are you even asking? I'm inclined to believe that question is false (yes, I think that makes sense to say).

---------- Post added 02-15-2010 at 06:45 PM ----------



I don't know what "non-external world" means. This is why I wrote earlier that I consider "external world" to refer to the same thing as "world" does.

No, stop that. Infinite regress, my friend. There's this "question everything" pandemic within society currently, and it has to stop. Someone started it thinking it was a good thing, and maybe it was at the time, but it has spawned a demon. A bloody demon. Now everyone I know questions everything, everything, even without reason. And all the while they think they're being intellectual for having done so. This is not rational thought, this is a form of paranoia, actually. It's worse than a stagnant mind, this repetitious, mindless, intensely skeptical doubt system people have in place.



People can be wrong. We cannot doubt logic and rational thought, for the moment we do we've gone mad, religious, or poetic. And though I have no problem with madness, religion, or poetry, we must not bring that sort of thing this way! Keep that over there! Far, far over there. Not near the science forum, and definitely not near the logic forum! :poke-eye:

"No, stop that." lol

I do not end with the doubt however. "the moment we do we've gone mad, religious, or poetic." I see the opposite! Or at least I see doubt as a great cure for the "rationale" of the mad, religious, or poetic (leaving poetic in there just for kicks). I think the pursuit of knowledge starts with doubting all things, not that it ends there.