My latest take on Descartes' Evil Demon Argument

Fafner

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.

Premise (2) is justified by the assumption that (a) and (b) are subjectively indistinguishable states of consciousness (an assumption which I shall not dispute), from which it seems to follow that no one could ever be entitled to believe that he's in state (a) rather than (b).

I believe, however, that premise (2) is inconsistent with premise (1), and so if (1) is true (and it's hard to see how it could be false, since (a) and (b) seem to be the only two relevant possibilities), it follows that (2) must be false. If now we combine premises (1) and (2) it seems that we must arrive at the following conclusion:

(*) 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. For it says that it's a logical possibility for an (a) state to be a (b) state, which is plainly absurd since (a) and (b) logically exclude one another. If I see truly that I have hands (a), it logically excludes my being in error (b), for it is impossible for me to have hands and also be a handless person deceived by the evil demon.

And this shows that the skeptic cannot assume that it is always possible for the subject to be in state (b), unless he can show that he is actually in that state--which of course he cannot do, since obviously no skeptic would claim to know that we are in fact being deceived by the evil demon. And so it follows that one cannot derive the radical possibility of skeptical error about our ordinary beliefs concerning the external world, from the mere subjective indistinguishably of veridical and non-veridical states of consciousness.

What do you think?

_db

But (2) is false: if I do in fact see that I have hands, it's impossible that Descartes’ evil demon deceives me (about my hands) since (a) and (b) are logically incompatible. Thus, the skeptic cannot assume that (2) is true unless he can prove that I’m in fact being deceived by Descartes’ evil demon (which of course he cannot). And so conclusion (3) doesn't follow. — Fafner

As a retort: but this is false: if an evil demon does in fact deceive you, then it is impossible that you are actually seeing your hands. Thus, the realist cannot assume that (2b) is true, where (2b) is that it is always logically possible that you are actually seeing your hands and are not deceived.

In other words I believe your argument is question-begging. Descartes' evil demon argument is aimed precisely at this epistemological ambiguity - the experience of seeing our hands is compatible with both hypotheses, and thus it cannot be assumed that one hypothesis is right.

Fafner

Thus, the realist cannot assume that (2b) is true, where (2b) is that it is always logically possible that you are actually seeing your hands and are not deceived. — darthbarracuda

I'm not sure what you mean here by "always logically possible". Surely if it seems to me that I see my hands, then it IS logically possible that I see my hands, if I in fact have them and am not deceived. Do you reject premise (1)?

What is wrong with the skeptical argument is that if premise (1) is true, then it's simply incoherent for the skeptic to maintain that I could be mistaken whether (a) or (b) is the case, since obviously if scenario (a) is the case, then I'm NOT mistaken. In other words, when the skeptic says "it's always possible that one is mistaken", it's not clear what he means by 'possible'. For if I do see (truly) that I have hands, then it is logically impossible for me to be in this very same state and be mistaken (that is, in the state of truly seeing that I have hands).

_db

In other words, when the skeptic says "it's always possible that one is mistaken", it's not clear what he means by 'possible'. For if I do see (truly) that I have hands, then it is logically impossible for me to bein this very same state and be mistaken. — Fafner

Well, we both presumably agree that what is the case is not the same thing as what could be the case. If I order a cup of coffee with no cream, there is a possibility that this cup of coffee will still have cream. What actually is the case is distinct from what is possibly the case.

To put it another way, then, I think possibility is a way of expressing indeterminacy and a lack of information. This is important in the field of statistics, but in the present case, the evil demon exists as a possibility because we do not have enough information to show that direct perception is actually the case. Possibility, in this situation, is basically identical to hypotheses.

Fafner

↪darthbarracuda

I do not wish do deny any possibilities. But what is crucial is HOW we describe those possibilities. If we agree that (a) and (b) are logically exhaustive, then the skeptic cannot, on pain of contradicting himself, maintain that whenever (a) or (b) is actually the case, I could be mistaken either way, because--by definition--I'm not mistaken if (a) is the case. So unless the skeptic can prove that (b) is actually the case, he is not entitled to premise (2).

Now, I grant the assumption that (a) and (b) are subjectivity indistinguishable mental states, but the crucial point is that they are DIFFERENT kinds of mental states nonetheless. The former is a state of seeing truly how things are in the world, while the latter isn't.

tom

(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. — Fafner

But why do you want to "know for sure"? How is that any better than to "know".

We are fallible beings, and we should be open to criticism of our theories. To "know for sure" serves no purpose than to deny criticism, thus preventing error correction.

Fafner

↪tom

I think the argument would still work even if you replace 'know for sure' with a simple 'know'. According to the skeptical argument, all possible evidence for any proposition cannot support the proposition any better than its negation. If every experience of the external world you could ever have, can potentially turn out to be mistaken, than what reasons (even weaker than perfect certainty) could you possibly produce in favor of believing that you are not radically mistaken about the external world?

tom

I think the argument would still work even if you replace 'know for sure' with a simple 'know'. According to the skeptical argument, all possible evidence for any proposition cannot support the proposition any better than its negation. If every experience of the external world you could have could turn out to be mistaken, then what reasons (even weaker than perfect certainty) could you possibly have for believing that you are not radically mistaken about the external world? — Fafner

"Radically mistaken" may be extreme language, but we "know for sure" we labour under certain misapprehensions.

The fact that we are mistaken about the external world (and the internal world) does not render our knowledge useless or completely without truth.

Theories do not require support. They stand on their own merit.

Shawn

Hi @Fafner, just wanted to say that it's awesome to see you.

Have you considered epistemological solipsism as a solution to the problem of asertaining certainty in the above cases presented by you?

Fafner

Nice to see you too @Posty McPostface, thanks =)

concerning your question, I'm not sure what you mean by "epistemological solipsism", could you elaborate?

Shawn

concerning your question, I'm not sure what you mean by "epistemological solipsism", could you elaborate? — Fafner

So, let me elaborate at the chance of sounding nonsensical. Doubt can only exist when there is lack of certainty. Solipsism is a certain belief. Therefore if one can doubt then solipsism is not an actuality, therefore your hands are real if you can doubt whether they are real...

Does that make sense?

Fafner

↪Posty McPostface

Well, if doubt can only exist when there is lack of certainty, and if one can doubt whether solipsism is an actuality, then at most it follows that solipsism is not certain. But I can't see how that proves anything about the existence of my hands.

Anyway, it seems to me like a weird strategy to affirm solipsism in order to refute skepticism, since the solipsist goes even further than the skeptic. And furthermore, solipsism is equally questionable as realism according to the skeptic, since you can't know neither the truth of solipsism nor realism.

Shawn

Well, if doubt can only exist when there is lack of certainty, and if one can doubt whether solipsism is an actuality, then at most it follows that solipsism is not certain. — Fafner

Well, not quite. Because since the world and the self are the same thing in solipsism, then there can be no room for doubting the world since the self must exist.

But I can't see how that proves anything about the existence of my hands. — Fafner

Well, the mere fact that you can doubt, presupposes that solipsism isn't the case, therefore they are real.

Hope I'm getting through...

Fafner

Well, not quite. Because since the world and the self are the same thing in solipsism, then there can be no room for doubting the world since the self must exist. — Posty McPostface

It seems to me that even if this inference is correct, it still would not refute skepticism because the skeptic need not argue for strict solipsism (in your sense) for his argument to be disastrous for knowledge. A world in which only I exits and the evil demon deceiving me into believing that there's an external world is just as bad as a strictly solipsistic world, but since it is not solipsistic in your sense, your argument is incapable of disproving its possibility. (because surely, in the Evil Demon world you CAN sensibly entertain (and hence doubt) both the hypothesis that the external world is real, and the possibility that you are being deceived by the demon.)

Janus

Well, the mere fact that you can doubt, presupposes that solipsism isn't the case, therefore they are real. — Posty McPostface

Doesn't it only, more modestly, presuppose that you don't know that solipsism is the case?

Shawn

It seems to me that even if this inference is correct, it still would not refute skepticism because the skeptic need not argue for strict solipsism (in your sense) for his argument to be disastrous for knowledge. — Fafner

Yes; but, I cannot doubt the fact that I am doubting. Therefore, if we take the evil demon path of assuming that everything can be doubted and nothing can be certain, then there's no room for doubt in the process of doubting itself. Hence, solipsism is false because you are doubting and are not certain, and doubt presupposes certainty. Thus, you doubting whether your hands are real means that you aren't living in a solipsistic world.

Shawn

Doesn't it only, more modestly, presuppose that you don't know that solipsism is the case? — Janus

The point is that epistemologically, you wouldn't even be able to entertain that thought in a solipsistic world, where everything is certain and there's no room for doubt.

Janus

↪Posty McPostface

Are you certain of that? Or is that just your way of defining solipsism?

Shawn

Are you certain of that? Or is that just your way of defining solipsism? — Janus

Yes, I'm quite certain that you cannot doubt in a solipsistic world since you are only aware of what you can know and there is no room for not knowing (doubt) since that is something beyond your known world.

Fafner

Therefore, if we take the evil demon path of assuming that everything can be doubted and nothing can be certain — Posty McPostface

Once again, the skeptic can restrict the scope of his skeptical claim and exclude the possibility of doubting one's doubt. The most interesting type of skepticism targets only the beliefs the could be doubted, but he is happy to exclude from his skepticism beliefs that logically cannot be doubted (such as the existence of the self, and perhaps some other things). But as it happens, the vast majority of our beliefs are such that they sensibly can be doubted, and thus if the skeptic is right then we are still in a serious epistemic trouble after all.

Shawn

Once again, the skeptic can restrict the scope of his skeptical claim and exclude the possibility of doubting one's doubt. — Fafner

But, that's cheating. For that removes any chance of certainty, but since knowledge is possible, then that excludes the possibility of that assertion.

Fafner

↪Posty McPostface

But again, if the skeptic is only a local and not a global one, he can argue, without inconsistency, that some things cannot be doubted, while retaining much of his skepticism about everything else.

Shawn

But again, if the skeptic is only a local and not a global one [...] — Fafner

Yes, but those limits can only be apparent to a person who can doubt or have a lack in knowledge. Therefore your hands are real, and the evil demon is... lying?

Fafner

↪Posty McPostface

Sorry I'm not following...

And of course the evil demon is merely an hypothesis, the skeptic doesn't actually claim to be able to prove that there is an evil demon (if this is what you meant).

Shawn

Ok, I'll repost what I already said on the issue in epistemological terms with a dreaming analogy representing 'solipsism':

If we inhabit a dream, for example, then there's no room for doubt because all your beliefs originate from yourself. I don't think that makes sense. What I'm getting at is that doubt can only exist if there is a lack in knowledge. In a dream everything is perfectly clear, there's no room for/to doubt the existence of the dream world itself because there is no room for doubt itself.

Janus

↪Posty McPostface

It's not logically impossible that I am the only being that exists but do not know it.

Fafner

In a dream everything is perfectly clear, there's no room for/to doubt the existence of the dream world itself because there is no room for doubt itself. — Posty McPostface

I think it's perfectly possible to ask yourself from within your own dream whether you are dreaming or not. Some people can in fact do just that (lucid dreamers).

Shawn

I think it's perfectly possible to ask yourself from within your own dream whether you are dreaming or not. Some people can in fact do just that (lucid dreamers). — Fafner

Not had you eternally been in a dream, and had no sense of doubt due to everything in the world being the same as your level of knowledge about it.

Fafner

Not had you eternally been in a dream, and had no sense of doubt due to everything in the world being the same as your level of knowledge about it. — Posty McPostface

But I don't see why does it have to be so.

And as I said before, even if we grant that you are correct, don't you agree that if an evil demon is causing your sensations (from outside your consciousness), you would then be able to doubt the evil demon world? (or imagine the scenario where the world has been completely destroyed 5 minutes ago, and only your brain is kept alive by the evil demon without you noticing anything. Surely in THIS world you can doubt both possibilities.)

Janus

↪Posty McPostface

I am pretty sure I have experienced doubt when dreaming.

Shawn

I'm just going to leave it to you guys to consider whether doubt is possible given the epistemological certainty presented in a solipsistic world.

My latest take on Descartes' Evil Demon Argument

Welcome to The Philosophy Forum!

Categories

More Discussions