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# G.E.Moore「Proof of an External World」#2 ムーアによる常識の擁護 [ 分析哲学 ] Moore declares that there is an external world because he proves it with his perfectly rigorous common sense method. But it is widely thought that the proof is unsuccessful because he begs the question of the external world. The sceptic (e.g. Lehrer cited in Lycan (2001)) objects that Moore does not really satisfy the (2) conditional for a successful proof because he knows the premises, here is a hand and here is another, but even he cannot know it. Hence, according to (1) and (3), because the conclusion follows from the premises, Moore’s proof should be inevitably questionable and unacceptable. In other words, the proof avoids an infinite regress or blatant circularity because it depends on the premises not to be certainly justified In fact, Moore actually ignores the sceptical argument, nor does he seem even ready to offer any considerations at all to support the premises that here is a hand and here is another. He says, “I can know things, which I cannot prove and among the things which I certainly did know, even if (as I think) I could not prove them, were the premise of my proof.”(PEW) Additionally, he suggests in another paper, A Defence of Common Sense (1925): “It seems to me that what is most amazing and most interesting about the views of many philosophers is the way in which they go beyond or positively contradict the views of Common Sense.” Indeed, Moore knows he has not provided a sufficient justification for the premises, and he also knows that he begs the question because he believes that it is possible to “philosophically” justify them. But Moore believes we “commonsensically” attain justification to believe the external world exists from our everyday experience (perceptual knowledge and common sense knowledge). He says: “How absurd it would be to suggest that I did not know it [here is a hand], but only believed it, and that perhaps it was not the case”. (PEW). Stroll argues that Moore deliberately refrained from explaining how he knew the premise of the proof in order to avoid confronting scepticism. Stroll argues: “Moore met this set of maneuvers by refusing to play the sceptic’s game. He did this by refusing to explain how he knows what he claimed to know. That refusal blocked the sceptical regress at its source; it made it impossible for the sceptic’s pattern of moves to get off the ground” (Stroll, 1994 cited in Landesman (1999)) According to Pryor (2000), Moore is a “dogmatist,” and Pryor claims that the dogmatist thinks that not only can we have perceptual knowledge and justified perceptual belief, we might have it without being in a position to cite anything that could count as ampliative, or to forced to give any question-begging evidence for those beliefs. Because Moore’s proof is dogmatic, the sceptic of course does not admit the proof as a persuasive argument. Stroud (1984, p86) makes clear the basis of the confrontation between the two positions. He finds two aspects in Moore’s proof. As we noted, Moore does not refute at all philosophical scepticism and answers affirmatively the problem of the external world; he also has three logical conditionals to establish the conclusion deduced from the premises. Stroud suggests that the fact that Moore’s proof does not answer a certain philosophical problem does not necessarily imply that there must be something wrong with the proof. He argues that everyday knowledge and the thesis of philosophical scepticism may be incompatible each other. Therefore, Moore’s anti-sceptical position can be equal to that of the sceptic because “what Moore says contradicts what the philosopher (the sceptic) says” (SPS, p126, pp211). The conflict between Moore and the sceptic can be briefly seen in the below example: The sceptic’s argument S1. D→～H* S2. D ------------------------------------------------------------------------ SC. ～H G.E.Moore’s argument M1. D→～H (which is identical with “H→～D”) M2. H ------------------------------------------------------------------------ MC. ～D *(D = I’m dreaming at t. H = I have a sufficient reason for believing “here is a hand” at t) Moore’s argument against scepticism simply runs the sceptic’s argument in reverse; it takes the negation of the sceptical conclusion as its main premise and vice versa. As their stating-point, both take the claim that if ‘I’m dreaming at t then I have a sufficient reason for believing “here is a hand” at t’ (S1 and M1). The sceptic accepts the first premise (M1), of the Moore’s proof; however, he is then in a position to derive the denial of the second premise (M2) of Moore’s proof, and S2 and M2 cannot be compatible. Therefore, while the sceptic concludes that I (the agent) cannot have knowledge of ‘here is a hand’ at t (commonsensical proposition) (SC), Moore contrarily concludes that that I (the agent) am not dreaming at t. Thus, it seems reasonable to suppose that Moore adopts a common sense position that ordinary people share, but only he is opposed to the philosophical sceptic. Because of that, we feel that “there is something ridiculous about the sceptical conclusion.” (Stroud, SPS, p119 pp200). In other words Moore tries to remind us of actual beliefs (e.g. here is a hand) we ordinary people already have. --- ## 注 --- ## 参考文献

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