Online research in philosophy

G.E. Moore thought that he could prove the existence of external things as follows: ‘Here is one hand, and here is another, therefore there are external things.’ Many readers of this proof find it obviously unsatisfactory, but Moore’s Proof has recently been defended by Martin Davies and James Pryor. According to Davies and Pryor, Moore’s Proof is capable of transmitting warrant from its premises to its conclusion, even though it is not capable of rationally overcoming doubts about its conclusion. In this paper, I argue that Davies and Pryor have it exactly backwards: Moore’s Proof is not capable of transmitting warrant from its premises to its conclusion, even though it is capable of rationally overcoming doubts about its conclusion.

Moore's proof of an external world is a piece of reasoning whose premises, in context, are true and warranted and whose conclusion is perfectly acceptable, and yet immediately seems flawed. I argue that neither Wright's nor Pryor's readings of the proof can explain this paradox. Rather, one must take the proof as responding to a sceptical challenge to our right to claim to have warrant for our ordinary empirical beliefs, either for any particular empirical belief we might have, or for belief in the existence of an external world itself. I show how Wright's and Pryor's positions are of interest when taken in connection with Humean scepticism, but that it is only linking it with Cartesian scepticism which can explain why the proof strikes us as an obvious failure.

Moore's 'Proof of an External World' has evoked a variety of responses from philosophers, including bafflement, indignation and sympathetic reconstruction. I argue that Moore should be understood as following Thomas Reid on a variety of points, both epistemological and methodological. Moreover, Moore and Reid are exactly right on all of these points. Hence what I present is a defence of Moore's 'Proof', as well as an interpretation. Finally, I argue that the Reid-Moore position is useful for resolving an issue that has recently received attention in epistemology, namely, how is it that one knows that one is not a brain in a vat?

Abstract: Some seventy years ago, G. E. Moore invoked his own sensory experience (as of a hand before him in the right circumstances), added some philosophical analysis about externality, and took himself to have offered his "Proof" of the existence of an external world. Current neo-Mooreans either reject completely the standard negative assessment of the Proof or qualify it substantially. For Sosa, the Proof can be persuasive, but only when read literally as offering reasons for the conclusion that there is at least one external object—rather than that the prover is justified in believing, or even knowing, that there is at least one external object. Sosa, then, is a neo-Moorean—though not of the sort we might expect in light of the ongoing debate about the Proof. I argue that Sosa needs to say more about the circularity often thought to vitiate the Proof before we can accept his view.

Moore’s proof of an external world is a piece of reasoning whose premises, in context, are true and warranted and whose conclusion is perfectly acceptable, and yet immediately seems flawed. I argue that neither Wright’s nor Pryor’s readings of the proof can explain this paradox. Rather, one must take the proof as responding to a sceptical challenge to our right to claim to have warrant for our ordinary empirical beliefs, either for any particular empirical belief we might have, or for belief in the existence of an external world itself. I show how Wright’s and Pryor’s positions are of interest when taken in connection with Humean scepticism, but that it is only linking it with Cartesian scepticism which can explain why the proof strikes us as an obvious failure.

This paper is concerned with real proofs as opposed to formal proofs, and specifically with the ultimate reason of real proofs (`Why Proof?') and with the notion of real proof (`What is a Proof?').

Preface -- Introduction -- There is only one reality -- The ultimate perspective and the ultimate drama -- Proof #1: Science -- Proof #2: History -- Proof #3: Prophecy -- Proof #4: Supernatural -- Proof #5: Psychology -- Proof #6: Sociology -- Proof #7: Inerrancy -- Proof #8: Micro-science -- Proof #9: Logic -- Proof #10: The only provably -- Inerrant, complete system -- Why proof is important -- Personal iplications of proof.

Few philosophers believe that G. E. Moore’s notorious proof of an external world can give us justification to believe that skepticism about perceptual beliefs is false. The most prominent explanation of what is wrong with Moore’s proof—as well as some structurally similar anti-skeptical arguments—centers on conservatism: roughly, the view that someone can acquire a justified belief that p on the basis of E only if he has p-independent justification to believe that all of the skeptical hypotheses that undermine the support lent by E to p are false. In this paper I argue that conservatism does not make trouble for Moore’s proof. I do this by setting up a dilemma concerning the notion of “justification to believe” that figures in conservatism. On one understanding of justification to believe, conservatism is subject to obvious counterexamples. On another understanding of justification to believe, conservatism is consistent with Moore’s “proof” conferring justification upon its conclusion. Since these two understandings exhaust the logical space, the conservative indictment of Mooreanism fails.

According to Moore, his argument meets three conditions for being a proof: first, the premiss is different from the conclusion; second, he knows the premiss to be the case; and, third, the conclusion follows deductively.2 Further conditions may be required, but he evidently thinks his proof would satisfy these as well. As Moore is well aware, many philosophers will feel he has not given “...any satisfactory proof of the point in question."3 Some, he believes, will want the premiss itself proved. But he has..

Moore’s proof consists of the inference of both “Two hands exist at this moment” and “At least two external objects exist at this moment” from the premise “Here is one hand and here is another.” The paper claims that the proof succeeds in refuting both idealism (“There are no external objects”) and skepticism (“Nobody knows that there are external objects”). The paper defends Moore’s proof against the following objections: Idealism does not deny that there is an external world so Moore’s proof is beside the point; Moore may be mistaken about the premise; Moore has failed to prove the premise; Moore has failed to show how he knows the premise; the proof leads to an infinite regress; the proof begs the question because the premise assumes what needs to be proved; the premise depends upon a shaky inference; the premise rests upon evidence of the senses and thus begs the question; the proof fails to convince the skeptic.