「確実性について」と反懐疑論9(ムーア1925,39) |
ムーア“common-sense” response to the sceptic
「外部世界が存在する」の証明
The response to scepticism put forward by Moore is ‘Moorean’ in the manner specified above at least in that it is in this veinスタイルthat Moore claimed that, contra the sceptic, he knew certain propositions that were typically thought to be open to sceptical doubt. In particular, Moore famously ‘proved’ the existence of the external world (and thus the denial of any sceptical hypothesis designed to show that there was no such world), by simply gesturing with his one hand and saying
“Here is one hand”, and then gesturing with the other and saying “And here is another”. Since, he claimed, he had established that he knew that he had two hands—and thus that two ‘external’ objects existed—so he had thereby established that he knew there was an external world as well.
Moore regarded this as being a perfectly “rigorous” proof, reminding us that [...] we all of us do constantly take proofs of this sort as absolutely conclusive proofs of certain conclusions—as finally settling certain questions, as to which we were previously in doubt. (Moore 1939,147)
「このページにはミスプリントが少なくとも3箇所ある」の証明
To illustrate this he gives the example of proving that there are at least three misprints on a page. To settle this question we simply look for one, then another, and then another. If this is an adequate ‘proof’ of the contested proposition in this context, then why should the gesturing of one’s hands be deficient in response to the sceptic? So Moore answers the sceptical challenge by straightforwardly affirming various contested propositions along with the empirical grounds he possesses which
justify this belief.
He also offers a further caveat注意: that, at the very least, the truth of these propositions is more certain than the soundness of any sceptical argument which is intended to counter our belief in them. So whereas the sceptic argues from doubt of a general anti-sceptical proposition, concerning, say, our relationship to the external world, to doubt of a class of everyday propositions which presuppose the truth of this anti-sceptical proposition, the ‘Moorean’ style of response is to argue from a putative instance of knowledge of one of the contested everyday propositions to knowledge of the general anti-sceptical proposition.
Moore, G. E. (1925). ‘A Defence of Common Sense’, Contemporary British Philosophy (2nd series),(ed.) J. H. Muirhead, Allen and Unwin, London.
Moore, G. E. (1939). ‘Proof of an External World’, Proceedings of the British Academy 25,273-300.