G. E. Moore |

**In this paper I will attempt to show the parallel connection between Moore's argument for the 'proof of an external world' (Moore, 1939) and the intuitive argument for skepticism. I will then present my objection to Moore's argument based on the ideas of contextualism and skepticism and consider Moore's possible replies to my objection.**

In this essay, 'S' will represent a subject, 'P' a skeptical hypothesis such as that I am a brain in a vat, and 'Q' a proposition S would ordinarily claim to know (about the world) such as that I am now sitting on a couch.

According to the intuitive argument for skepticism, if we accept the two given premises (that a) S does not know that not-P, and b) if a) is true, then S does not know that Q), then we are to accept the logical conclusion - that S does not know that Q.

In response, Moore argues that external objects exist (not-P), with his proof being that he knows he has two hands (Q), whose existence he can prove by '[h]olding up [his] two hands, and saying, ... 'Here is one hand' ... 'and here is another'.' (Moore, 1939: 24). In other words, a) S knows that Q, b) If a) is true, then S knows that not-P, therefore, S knows that not-P.

Premise (b) of each argument are identical as the form 'if p then q' is logically equivalent to 'if not-q, then not-p'. Then, Moore's argument reversed, 'if S knows that not-P, then S knows that Q, therefore S knows that Q', is equivalent to the intuitive argument.

However, despite the arguments' seemingly possible and truthful interchangeability, I do not believe that they are the same arguments merely reversed, and that in this case, Moore's argument is one to be revised. According to contextualism, what needs to be taken into account in order to judge the truthfulness of Moore's argument is the context in which it is said (DeRose, 1999: 187). In the context of this skeptical argument, proof of the existence of hands (Q) employs 'high' standards to be met for its truth (DeRose, 1999: 188) since 'hands' are not merely representative of the body parts but of an external world (not-P). That is, Moore's knowledge of the physical presence of his hands which would be a plausible proof in ordinary circumstances, does not have the same meaning within this context in which it plays a significant role; the proof needs to provide an adequate evidence by which S knows that S is not a 'brain in a vat'.

Then, Moore, by simply dismissing skepticism and its standards for truth about Q as 'absurd' (Moore, 1939: 24) and refusing to employ the same standards, thereby dismisses himself from the context of the argument. Thus, Moore's argument, although logically equivalent, is not truthfully equivalent to the intuitive argument.

Moore's response to my objection, I suspect, would be that of the invariantists' (Moore, 1999: 188) that his knowledge of Q therefore not-P remains true regardless of the context in which it is asserted, and moreover, that we can know things which we cannot prove (Moore, 1939: 26), and that it is more rational to be certain about his knowledge of Q than about the skeptics' denials of it (Moore, 1959: 226). However, it is clear that Moore's argument is addressing the philosophical skeptics' argument, not a mere utterance of his opinions. Then, I believe a more "rational" approach is to remain within the context of the original and overall argument (where 'proof' is essential) and explain why and how he believes that Q regardless of how absurd it seems to question it, rather than to disregard skepticism completely.

References

In this essay, 'S' will represent a subject, 'P' a skeptical hypothesis such as that I am a brain in a vat, and 'Q' a proposition S would ordinarily claim to know (about the world) such as that I am now sitting on a couch.

According to the intuitive argument for skepticism, if we accept the two given premises (that a) S does not know that not-P, and b) if a) is true, then S does not know that Q), then we are to accept the logical conclusion - that S does not know that Q.

In response, Moore argues that external objects exist (not-P), with his proof being that he knows he has two hands (Q), whose existence he can prove by '[h]olding up [his] two hands, and saying, ... 'Here is one hand' ... 'and here is another'.' (Moore, 1939: 24). In other words, a) S knows that Q, b) If a) is true, then S knows that not-P, therefore, S knows that not-P.

Premise (b) of each argument are identical as the form 'if p then q' is logically equivalent to 'if not-q, then not-p'. Then, Moore's argument reversed, 'if S knows that not-P, then S knows that Q, therefore S knows that Q', is equivalent to the intuitive argument.

However, despite the arguments' seemingly possible and truthful interchangeability, I do not believe that they are the same arguments merely reversed, and that in this case, Moore's argument is one to be revised. According to contextualism, what needs to be taken into account in order to judge the truthfulness of Moore's argument is the context in which it is said (DeRose, 1999: 187). In the context of this skeptical argument, proof of the existence of hands (Q) employs 'high' standards to be met for its truth (DeRose, 1999: 188) since 'hands' are not merely representative of the body parts but of an external world (not-P). That is, Moore's knowledge of the physical presence of his hands which would be a plausible proof in ordinary circumstances, does not have the same meaning within this context in which it plays a significant role; the proof needs to provide an adequate evidence by which S knows that S is not a 'brain in a vat'.

Then, Moore, by simply dismissing skepticism and its standards for truth about Q as 'absurd' (Moore, 1939: 24) and refusing to employ the same standards, thereby dismisses himself from the context of the argument. Thus, Moore's argument, although logically equivalent, is not truthfully equivalent to the intuitive argument.

Moore's response to my objection, I suspect, would be that of the invariantists' (Moore, 1999: 188) that his knowledge of Q therefore not-P remains true regardless of the context in which it is asserted, and moreover, that we can know things which we cannot prove (Moore, 1939: 26), and that it is more rational to be certain about his knowledge of Q than about the skeptics' denials of it (Moore, 1959: 226). However, it is clear that Moore's argument is addressing the philosophical skeptics' argument, not a mere utterance of his opinions. Then, I believe a more "rational" approach is to remain within the context of the original and overall argument (where 'proof' is essential) and explain why and how he believes that Q regardless of how absurd it seems to question it, rather than to disregard skepticism completely.

References

**DeRose, K. "Contextualism: An Explanation and Defense." In The Blackwell Guide to Epistemology, ed John Greco and Ernest Sosa, Oxford: Blackwell Publishers 1999. ISBN: 0-631-20290-0.**

**Moore, G.E. 1959. Philosophical Papers. London: George Allen & Unwin LTD.**

**Moore, G.E. "Proof of an External World." Reprinted in Epistemology: An Anthology, ed Ernest Sosa and Jaegwon Kim, Oxford: Blackwell Publishers, 2000. ISBN: 0-631-19723-0.**

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