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# G.E.Moore「Proof of an External World」#3 ムーア批判 [ 分析哲学 ] Nevertheless, although Moore deliberately avoids the sceptical argument in order to build up own anti-sceptical argument, Wright (2003) argues that even if Moore knows all the premises (here is a hand and here is another) to be true, he cannot reach the conclusion that there are some external objects from the premises. His knowledge of the premises does not transmit across the proof to the conclusion, and the proof is not cogent inference. The proof suffers from what Wright calls “transmission failure.” To make his objection clear, he reforms Moore’s proof in the following way: I. My current state of consciousness is in all respects like being aware of a hand held up in front of my face II. Here is a hand ------------------------------------------------------------------------ III. There is a material world (since any hand is a material object existing in space) In other words, the proof is a plainly circular argument. The evidence stated in I can furnish people with knowledge that II is true if they (independently of I) have knowledge that III is true. Therefore, Wright concludes people cannot acquire the knowledge that III is true by deducing it from II because they must have independent knowledge that III is true in order for having knowledge that II is true on the basis of I. According to Wright, whereas the proof of misprints is actually cogent, Moore’s proof is clearly distinct from this kind of proof and is not cogent. However, Pryor (2004) concedes that Moore's argument is cogent and, thus, it does not beg the question in Wright's sense. Pryor describes two epistemologies of perception: the conservative (Wright’s) and the dogmatist (Moore’s and Pryor’s). In Wright's view, a justification for the conclusion that there are material objects is necessary if our experience is to justify belief in the premises. By contrast, Pryor argues that no such justification is required. Although evidence for the premises would be defeasible in principle by doubt that the external world exists, to contradict that doubt would not itself require evidence. According to Pryor, the belief “here is a hand” is a “perceptually basic belief” (a type of belief that one can be warranted in having simply by taking one's experience at face value, without further assumption, provided one has no reason to doubt that the external world exists). Our experiences representing “here is a hand” make us prima facie justified in believing the empirical proposition by itself. And if justification for the belief does not depend on having an antecedent justification for the belief in the existence of the external world, it can transmit to the conclusion across that valid inference. It follows that if someone were open-minded about whether the external world exists, then by running Moore's argument they could acquire a justification for believing that it does. However, Stroud (1984) unfavourably evaluates Moore’s commonsensical position against philosophical scepticism. He says that the efficiency of Moore’s argument depends on the source of the philosophical conclusion. In other words, it is not always possible to reject a denial of knowledge by simply appealing to, as Moore did, some particular thing that is already known. He demonstrates the root of the conflict between the sceptic and Moore by using an example that he calls “the detective and his apprentice” (SPS, p108-109).The detective is the sceptic, and his apprentice is Moore. According to the example, a murder takes place, and the crime is investigated by a master detective and his apprentice. The apprentice gets from a butler a list of all who were in the house where the crime took place. This means that someone from the list could possibly have committed the murder. He properly considers them all and then concludes the butler is the murderer, saying ”we now know that the butler did it.” So if a reporter who doesn’t know anything about the case objects to this conclusion and says that it is still not known who did the crime, the apprentice can successfully refute him by only saying, ”No, I know that the butler did it.” In this case he could argue that, “what the reporter said implies that I do not know that the butler did it, but I do know that the butler did it, so what the reporter said is not true. That is a conclusive argument”(SPS, p109). This line of reasoning is the same as Moore’s claim that he defeats the sceptic simply by affirming, “Here is a hand.” Nevertheless, the master detective replies to the apprentice’s conclusion that there is a possibility that someone who is not on the list and was in the house at the time committed the murder. And he says, “we still don’t know who did it.” Stroud suggests this is a successful objection to the apprentice’s claim to knowledge since the detective, unlike the reporter, criticises the apprentice’s knowledge by pointing out the putative basis of his conclusion. That is to say that in case the actual possibility which is compatible with all the apprentice’s evidence for his claim, it would mean that he does not know that the butler did it. By using this example, Stroud gives a philosophical critique of Moore’s commonsense argument. He states: “From the ‘assumptions’ said to be behind Russell’s sceptical conclusion it does indeed follow that Moore does not know that this is a pencil [i.e. here is a hand]. But if those ‘assumptions’ are nothing more than truths unavoidably involved in any general assessment of our knowledge of the world, Moore does not successfully refute them [by simply appealing to his knowledge that his hand exists] any more than the apprentice refutes the detective” (SPS, p111). In other words, Stroud argues that we cannot dismiss sceptical arguments without providing a deeper and more philosophical answer to the sceptic. Due to some severe criticisms of the proof, many believe that Moore’s refutation of the sceptic is unsatisfactory. Some have said that, “Moore has since been left for dead” (Lycan, 2001). Yet some philosophers who sympathize with Moore;they are called the new “Mooreans.” We have seen already one of them, Pryor, and moreover, Lycan (2001) also defends Moore and contradicts Stroud’s objections. Lycan argues with Stroud’s implication that Moore’s proof needs a more philosophical answer to scepticism, and the consequence of Stroud’s position, that philosophy is higher and a more authoritative position than our ordinary perceptual and commonsensical position. H also claims that, “there is nothing deeper in all of philosophy than Moore’s response to the skeptic” (2001). --- ## 注 --- ## 参考文献

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