I think one might be applying a semantic overburden to poor old Descartes and his omnipotent demon.

Descartes purpose in the application of the Demon was to prove with consummate genius that only thought exists. If the evil demon can fool me into thinking that everything I am thinking is a delusion it follows that I can prove nothing to exist as all existence may be a deception.

Upon this basis Descartes establishes the premise of absolute doubt. This premise is too often relied upon by the amateur philosopher who can then dismiss any assertion pertaining to 'existent reality' upon the basis of the deceiving demon, or the premise that reality is believed to be real in dreams and therefore we have little call or proof to assert that it is more real when we are awake. The dream analogy and that of the demon are Descartes' fait accompli, for any assertion that reality might be firmly established beyond doubt.

However in his second meditation Descartes applies the notion of universal doubt, to bring us to an incontrovertible truth of the existence of 'something'.

Unfortunately a difficulty arises when Descartes expands that something to include something else.

The something that Descartes successfully proves in his second meditation is the existence of thought.

" But [suppose] there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case too I undoubtedly exist, if he is deceiving me; and let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something. So after considering everything very thoroughly, I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind."

There must be thought if indeed a demon is to pervert that thought. Thought cannot be perverted into believing that it (thought) does not exist.

This much, as the proof pertains to thought is incontrovertible, however Descartes applies a strict association of thought with an I thinking. At this juncture Cartesian philosophy begins to weaken. All that has effectively been proven is the existence of thought, yet the Demon might well be deceiving this " I" into believing that there is an " I" thing who does the thinking or even generates the thought independently. Because thought exists the existence of an I thinking does not necessarily follow.

Nietzsche addresses this fallacy quite beautifully and quite thoroughly in aphorism 17:

"So far as the superstitions of the logicians are concerned, I will never tire of emphasizing over and over again a small brief fact which these superstitious types are unhappy to concede - namely, that a thought comes when "it" wants to and not when "I" wish, so that it's a falsification of the facts to say that the subject "I" is the condition of the predicate "think." It thinks: but that this "it" is precisely that old, celebrated "I" is, to put it mildly, only an assumption, an assertion, in no way an "immediate certainty." After all, we've already done too much with this "it thinks": this "it" already contains an interpretation of the event and is not part of the process itself. Following grammatical habits we conclude here as follows: "Thinking is an activity. To every activity belongs someone who does the action, therefore -." With something close to this same pattern, the older atomists, in addition to the "force" which created effects, also looked for that clump of matter where the force was located, out of which it worked - the atom. Stronger heads finally learned how to cope without this "remnant of earth," and perhaps one day people, including even the logicians, will also grow accustomed to cope without that little "it" (to which the honourable old "I" has reduced itself)."

As such we are left with thought, nothing more and nothing less. The question then follows what is to be done with this thing... thought.

M

Because thought exists the existence of an I thinking does not necessarily follow. — Marcus de Brun

Except that the mineness or ownedness of thought is unquestionable. Thoughts always belong to someone; they do not float around freely.

Except that the mineness or ownedness of thought is unquestionable. Thoughts always belong to someone; they do not float around freely.

Thats interesting Janus, how did you arrive at this conclusion/assumption?

Did you read aphorism 17?

Not a Nietzsche fan I take it?

Please expand

M

Aphorism 17 is agreeable enough, and contradicts nothing I have said. How are thoughts known to us? By experience just like everything else, no? Have you ever experienced a thought that wasn't your own? (Note, I'm not taking about origins here).

Aphorism 17 questions the presumptive basis of the "I" You state that this is agreeable enough and yet you ask me to assume an "I" in order to answer the question.

If you are asking me if I believe that my thought belongs to me, I can only reply that I have no evidence to prove that it does and might best assume that it does not. It may tell me that I am an " I" .....but it also tells me lots of other things that are equally dubious.

All this 'putative "I" can assert, is that thought exists, it offers the tempting indulgence of a "me" and it appears to this 'me'.... to be having a good time doing so, possibly at the expense of the I or the me rather than to the benefit or even the proof of it.

If deterministic principles are true then this I is a foregone conclusion, all that it does is act out a material existence that was established at the point eruption of the big bang. As such I find the "I" to be a rather boring and somewhat predictable material entity.

It is the thought that is interesting from a thoughtful perspective, the material 'I' is destined to feed the maggots, however the thought on the other hand appears to originate from something potentially interesting.. it might even endure after the maggots.

M

I shall consider the following argument for skepticism:
(1) Either (a) I see that I have hands or (b) it merely seems to me that I have hands because I’m deceived by Descartes’ evil demon.
(2) According to the skeptic, whenever I seem to see that I have hands, it is always logically possible that I’m deceived by Descartes’ evil demon.
(3) Hence I can never really know for sure whether I really have hands.
...
(*) Whenever it seems to the subject that he's in state (a), it is always possible for him to actually be in state (b).

But (*) is incoherent. — Fafner

As I see it, if (1)(b) is logically possible, then (*) is coherent. That it seems to the subject that he's in state (a) (and (b) seems impossible to him) doesn't imply that he's in state (a). Which leaves (b) as a logical possibility.

A different response is to reject (1)(b) as logically possible. That seems consistent with ordinary usage where the meaning of "hands" is defined by that use. And so the only alternative to (1)(a) is ordinary deception or error rather than systemic deception or error (e.g., it's logically possible that the subject's real hands have been amputated and he presents fake hands). So for the skeptic's argument to work, a speculative meaning (or use) of "hands" is required.

(Of course, knowledge could still be challenged on the basis of ordinary deception and error, but that's a separate argument.)

Going back to the original post here - insofar as you are trying to represent Descartes in any case - the argument would probably better be expressed as a modus tollens:
1) If seeming to see my hand were sufficient evidence for knowing that I see my hand, I would be able to distinguish the following two cases merely on the basis of seeming to see my hand:
a) My seeming to see my hand being the result of my actually seeing my hand.
b) My seeming to see my hand being the result of an evil demon playing with my mind.

2) Merely on the basis of seeming to see my hand, I cannot distinguish case (a) from case (b).

Therefore, seeming to seem my hand is not sufficient evidence for knowing that I see my hand.

That seems to get around the problem you are presenting the skeptic, since it is no longer being expressed in terms of two allegedly inconsistent premises. Instead it is expressed as one conditional premise, together with the claim that the consequent of that conditional is false.

To get a general skeptical conclusion of course you'd need to add a premise to the effect that to know that you see your hand you need sufficient evidence for knowing that you see your hand. If you add that premise, though, the Wittgensteinian approach that not all knowledge requires evidence comes in.

There’s a ‘meta-consideration’ to take into account with Descartes’ argument. It is that Descartes wishes to ground knowledge in reason. His ‘clear and distinct ideas’ are, after all, apodictic truths such as the law of identity. And so in some ways, Descartes is merely elaborating, or re-stating, the ancient rationalist attitude, namely, that the truths of reason are more trustworthy than those of the treacherous senses. Of course, putting it so baldly is like reducing an opera to a synopsis, as Descartes’ genius lies in the precise way that he goes about establishing his claim. But that, I think, has a lot to do with the gist of it.

As I see it, if (1)(b) is logically possible, then (*) is coherent. That it seems to the subject that he's in state (a) (and (b) seems impossible to him) doesn't imply that he's in state (a). Which leaves (b) as a logical possibility. — Andrew M

Notice that I don't wish to deny the possibility to be in state (1b), of course that is a logical possibility. What I do deny is the possibility that one could be in the very same mental state as in (1a) and be deceived.

The skeptic of course doesn't claim to know whether I'm in state (1a) or (1b), but he claims that even if I'm lucky and I'm in fact in state (1a), the possibility of a mistake still exists, which I cannot rule out. But my point is that if one is in fact in state (1a) then there's no possibility of him to have the same experience and be mistaken.

Another thing that no one seems to think about is how do we know that the evil demon isn't being fooled by another more powerful evil demon and so on ad infinitum. If it is possible that we are being fooled by an evil demon then it is also possible that the evil demon is being fooled as well. You end up requiring an omniscient being to stop the infinite regress. Then we arrive at the problem of omniscience.

As such we are left with thought, nothing more and nothing less. The question then follows what is to be done with this thing... thought. — Marcus de Brun

And so you've proved that thought alone exists. To whom?

The skeptic of course doesn't claim to know whether I'm in state (1a) or (1b), but he claims that even if I'm lucky and I'm in fact in state (1a), the possibility of a mistake still exists, which I cannot rule out. But my point is that if one is in fact in state (1a) then there's no possibility of him to have the same experience and be mistaken. — Fafner

I agree that it's not possible to see your hands and be mistaken. But that is not what the skeptic is saying. The skeptic is saying that even if you do see your hands the possibility of being mistaken remains. The skeptic's claim is coherent if possibility is understood as a function of the information available to the subject rather than in an absolute (God's eye view) sense.

One evil demon is enough to get the skeptical argument about certainty going - in fact you don't strictly speaking need the evil demon in any case. If you burrow into Descartes's argument it is, in the abstract, simply based on the idea of the fallibility of all processes, and that obtaining knowledge is a process. He "gets around" this by introducing his clear and distinct ideas which provide us with knowledge without having to go through a process of acheiving it.
We've long since moved on from Descartes obsession with certainty - but he changed the terms of the philosophical debate: prior to him the big distinction in metaphysics was between form and content, after him it was all about mind and matter.

And so you've proved that thought alone exists. To whom?

To itself alone.

M

One evil demon is enough to get the skeptical argument about certainty going - in fact you don't strictly speaking need the evil demon in any case. If you burrow into Descartes's argument it is, in the abstract, simply based on the idea of the fallibility of all processes, and that obtaining knowledge is a process. — MetaphysicsNow

What do you mean "falilibility" of all processes? How do they fail? Is it our senses that fail us, or our interpretation of what they represent? When you say, "all processes" do you also mean processes like fusion and the evolving process of organisms by natural selection? Did natural selection fail in some way? By whose standards?

He "gets around" this by introducing his clear and distinct ideas which provide us with knowledge without having to go through a process of acheiving it. — MetaphysicsNow

Why would one want to get around facts if one is trying to get at knowledge? We have instinctive knowledge and we have learned knowledge. Which one are you talking about?

We've long since moved on from Descartes obsession with certainty - but he changed the terms of the philosophical debate: prior to him the big distinction in metaphysics was between form and content, after him it was all about mind and matter. — MetaphysicsNow

Well, that's the thing. There is no distinction. Dualism is false. Mind and matter interact so they are made of the same substance. Whether you want to call that substance "non-physical/mental", or "physical/matter", does it really matter? No, it doesn't. Descartes went through all that trouble for nothing.

You see skin covering your hands, and are blind to the bulk of what you call your hands. If you see just a very small fraction of what your hands look like, then the mass of your hands remains unseen to you. So, even without the demon, you see about as much of your hands as an ant sees a city.

, basically what you are saying is that, within a given context, the proposition "I have hands" is either true or it is false. In other words, either I really do have hands or I don't. As such, it it is not possible that "I have hands" and "I don't have hands" are both false within the same context. Therefore, it is not possible that I could always be wrong no matter what I believe, because something has to be the case.

Makes sense to me.