It may seem more palatable to the devout to consider the possibility that I systematically deceive myself or that there is some evil demon who perpetually tortures me with my own error.
So the dreaming argument leaves unchallenged our belief in general truths about the world (the belief that there are physical objects, that they move in such-and-such ways, etc.) Also, the dreaming argument does not give Descartes reason to doubt his beliefs about mathematics and the like.
How would you know the difference between the dream world and the real world?" Descartes thinks these considerations about dreaming give him reason to doubt all of his sensory beliefs, even ones where there seems to be ample lighting, where the objects seem to be close by, and so on.
The argument “I may be dreaming” is senseless (sinnlos) for this reason: If I am dreaming, this remark is being dreamed as well—and indeed it is also being dreamed that these words have any meaning (diese Worte eine Bedeutung haben.)
Rene Descartes’s theory that one is unable distinguish being awake from dreaming, as interesting as it is, can be at times a little farfetched, along with a few contradictions to himself, Descartes’s dream argument does not entitle himself to any sort of claim....
The argument “I may be dreaming” is senseless for this reason: if I am dreaming, this remark is being dreamed as well—and indeed it is also being dreamed that these words have any meaning.
Which is needed for the argument? If we add(7A) to (6), (8) does not follow. For (6) says only that its possibleI am dreaming and mistaken, not that I actually am mistaken, which is whatwe would need to get (8) from (7A). On this interpretation, the DreamArgument is invalid. (7B), on the other hand, makes the inferencestraightforwardly valid.
It is interesting and informative to compare Wittgenstein’s approach to the Dream Scenario with Moore’s. Moore was, of course, a distinguished philosopher in his own right; but Wittgenstein’s understanding of the Dream Hypothesis exhibits a profundity that well eclipses Moore’s. Unlike Moore who assumed that the Cartesian hypothesis had to be met with a counter-proof, Wittgenstein is cutting it off at its source by giving reasons why it does not make sense.
The Evil Genius The hypothesis that you are really only dreamingis what philosophers call a skeptical possibility; the philosopher challengesyou to rule it out somehow or otherwise justify your contrary belief. The Evil Genius hypothesis is another such skeptical possibility, as arethe brain-in-vat hypothesis and various virtual-reality hypotheses. The difference between the Dream hypothesis and the Evil Genius hypothesisis only that the latter cuts deeper, threatening your most basic conceptsand even your deductive reasoning ability. The Evil Genius couldnot only feed you spurious experiences but mess directly with your cognitivepowers, making an inference seem valid to you when in fact its not.
The Evil Genius Argument (which I wont spell outhere) goes much as the Dream Argument did, and appeals to the same principle(7) connecting knowing with possibility. But its conclusion is moreambitious: that I have no knowledge whatever, let alone empirical knowledge.
In the three places in the writings of the Third Wittgenstein that treat the Dream Hypothesis, (Zettel, 396, OC 383, and 676) there are no explicit arguments showing that the conception is senseless, but there are remarks that can be construed as submerged arguments to this effect. Let us look seriatim at these entries to see if we can explicate his reasoning. In OC 676 the interlocutor is suggesting that it is possible that one might be drugged, and in that case one may well be mistaken about whether or when he has traveled. A guiding presupposition underlying the interlocutor’s objection is that the effect of drugging could render a person unable to know where he is or what is happening to him. Wittgenstein interprets the assumption more strongly than the interlocutor intends, that is, as implying that the drugged person is unconscious. His response is to insist that one who is unconscious is “not really talking and thinking.” His point is that a person who is not talking and thinking is not making a sensible assertion. This idea rests on a familiar thesis in all of Wittgenstein’s later writings, namely, that certain background and contextual conditions have to be satisfied if an utterance is to count as a statement. And one of these conditions is that the person must be awake if his utterances are to be significant. The condition is obviously unfilled if the person is asleep and dreaming. Wittgenstein’s way of formulating this condition is to say that a sleeping person is neither talking nor thinking.
Peirce I said that the Dream and Evil Genius Arguments failbecause (7B) begs the question. Yet we should not simply write offthose arguments, because people feel the attraction of (7B), even if theythen do reject it as question-begging. That attraction still needsto be explained. Thats where Peirce comes in. He in effectadmits that (7B) contains some truth, indeed important truth; its justthat that truth has been exaggerated.
Moore’s autobiography was published in 1942, not long after his career as a teacher at Cambridge had ended. He is characteristically frank and honest in acknowledging that Wittgenstein used a method for dealing with philosophical problems that he (Moore) was never able to understand clearly enough to use himself. Wittgenstein’s treatment of the Dream Hypothesis is a good example of their differing approaches to such worries. Moore was, as I have said, a distinguished thinker by any standard. If a list of great British philosophers from Hobbes through Russell, were to be drawn up, Moore would obviously rank very high in that selection. But as our description of Wittgenstein’s assessment of The Dream Hypothesis shows, Moore was no Wittgenstein.