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. (shrink)

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. (shrink)

The existence of objects external to the mind is a proof-condition for the type of object demonstration Moore provided in his famous lecture. Affirming the existence of objects external to the mind is just a way of saying that one person can show (present, demonstrate) something to another to prove it is so, to prove it exists, Demonstrations like that are conclusive and immune to scepticism.

SummaryThere is an enormous literature on Moore's so‐called “proof”per se, but practically nothing has been written on the distinctions upon which the proof is bases, such as “being presented in space” and “being met with in space”. These are crucial to the argument, since Moore wishes to draw the line between the external and internal world via such distinctions. The author argues that these distinctions themselves crucially depend on a point that Moore does not argue for, (...) but assumes, namely that afterimages, negative after‐images, some sense‐data and pains are private to those that have them, and that two different people cannot sense numerically the same after‐images, pains etc. The author shows that this assumption is nonsense and that the entire proof, based upon it, therefore fails. (shrink)

We develop a reading of Moore’s “Proof of an External World” that emphasizes the connections between this paper and Moore’s earlier concerns and strategies. Our reading has the benefit of explaining why the claims that Moore advances in “Proof of an External World” would have been of interest to him, and avoids attributing to him arguments that are either trivial or wildly unsuccessful. Part of the evidence for our view comes from unpublished drafts which, (...) we believe, contain important clues concerning Moore’s aims and intent. While our approach to PEW may be classified alongside other broadly "metaphysical" readings, we believe that a proper recognition of the continuity in Moore’s philosophical concerns and strategies across his philosophical career shows that the customary distinction between "epistemological" and "metaphysical" interpretative approaches to PEW is at best superficial. (shrink)

(2008). Neither Dogma nor Common sense: Moore's confidence in his ‘proof of an external world’1. British Journal for the History of Philosophy: Vol. 16, No. 1, pp. 163-195.

A new reading of G.E. Moore's ‘Proof of an External World’ is offered, on which the Proof is understood as a unique and essential part of an anti-sceptical strategy that Moore worked out early in his career and developed in various forms, from 1909 until his death in 1958. I begin by ignoring the Proof and by developing a reading of Moore's broader response to scepticism. The bulk of the article is then devoted to understanding (...) what role the Proof plays in Moore's strategy, and how that role is played. (shrink)

A common view about Moore’s Proof of an External World is that the argument fails because anyone who had doubts about its conclusion could not use the argument to rationally overcome those doubts. I agree that Moore’s Proof is—in that sense—dialectically ineffective at convincing an opponent or a doubter, but I defend that the argument (even when individuated taking into consideration the purpose of Moore’s arguing and, consequently, the preferred addressee of the Proof) does not (...) fail. The key to my defence is to conceive the Proof as addressed to subjects with a different epistemic condition. To sustain this view I formulate some hypothesis about the common general purpose of arguing and I defend that it can be fulfilled even when the addressee of an argument is not someone who disbelieves or doubts its conclusion. (shrink)

This paper argues that we should reject G. E. Moore’s anti-skeptical argument as it is presented in “Proof of an External World.” However, the reason I offer is different from traditional objections. A proper understanding of Moore’s “proof” requires paying attention to an important distinction between two forms of skepticism. I call these Ontological Skepticism and Epistemic Skepticism. The former is skepticism about the ontological status of fundamental reality, while the latter is skepticism about our empirical (...) knowledge. Philosophers often assume that Moore’s response to “external world skepticism” deals exclusively with the former, not the latter. But this is a mistake. I shall argue that Moore’s anti-skeptical argument targets an ontological form of skepticism. Thus, the conclusion is an ontological claim about fundamental reality, while the premises are epistemic claims. If this is correct, then the conclusion outstrips the scope of its premises and proves too much. (shrink)

In the third Meditation once having arrived at the conclusion that a perfect being exists, Descartes infers that this perfect being could not be a deceiver. I maintain that there is no valid way he can move from his conclusion that a perfect being exists to the conclusion that this being cannot be a deceiver. In order to see the difficulties with this inference it is necessary to examine the use of the idea of perfection in the argument for the (...) existence of the perfect being, but I will not otherwise concern myself with the validity of the argument for the existence of God. (shrink)

Heidegger says concerning the question of the possibility of a proof of the existence of an external world that ‘the “scandal of philosophy” is not that this proof has yet to be given, but that such proofs are expected and attempted again and again’. Heidegger thinks this because our being is in the world, and this is something which Descartes for one failed to appreciate. I am not concerned here to answer the question whether Heidegger's (...) own views on these matters will do, though I think that they will not. Indeed they might well be said to beg the question at issue, in that Heidegger starts from the presumption that we are actually in the world, even if we are not in it in the way in which the tree in the garden is. Another way of reacting to Heidegger would be to say that he does not treat the fact and force of scepticism seriously enough when he makes that presumption. After all, it is possible for us to raise sceptical doubts about the existence of a world apart from ourselves, while it is not possible for the tree in the garden to act similarly. Hence, even if we make the presumption that we are in the world, as Heidegger insists, we are in it in a way that leaves untouched the possibility of sceptical doubts about what that world and our being in it are like. It might, logically, be the case, for example, that the world consists of just me and that my being in the world is no more than for me just to exist. In other words, my being in the world does not directly entail that there exists a world apart from me. (shrink)

This article develops a logical (or semantic) response to scepticism about the existence of an external world. Specifically, it is argued that any doubt about the existence of an external world can be proved to be false, but whatever appears to be doubt about the existence of an external world that _cannot_ be proved to be false is nonsense, insofar as it must rely on the assertion of something that is logically impossible. The article (...) further suggests that both G. E. Moore and Ludwig Wittgenstein worked towards the same solution but left their work unfinished. (shrink)

In Descartes's _Third Meditation, the mediator states that he may have unknown faculties that could cause his ideas of corporeal things. His proof of the external world in the _Sixth Meditation, however, clearly relies on the assumption that he does not have such unknown faculties. This paper examines Lex Newman's attempt to resolve this apparent inconsistency. I argue that the attempt is not altogether successful.

I argue that descartes' doubting of the external world does not rest on doubting the truth of clear and distinct ideas. in fact, he denies that we clearly and distinctly perceive the "existence" of material things. thus, their existence is not established through the validation of such ideas and we can understand why descartes' argument for their existence takes the form it does. i suggest that dreams lead him to conclude that the existence of material things is not (...) clearly perceived and to doubt their existence. (shrink)

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. (shrink)

Realism, defined as a justified belief in the existence of the external world, is jeopardized by ‘meaning rationalism,’ the classic theory of meaning that sees the extension of words as a function of the intensions of individual speakers, with no way to ensure that these intensions actually correspond to anything in the external world. To defend realism, Ruth Millikan ( 1984 , 1989a , b , 1993 , 2004 , 2005 ) offers a biological theory of (...) meaning called ‘teleosemantics’ in which words, without requiring any contribution from the speaker’s intensions, are supposedly matched directly with their extensions by external norms. But even if one granted as a theoretical possibility that word meaning might possibly be stabilized through an external process, nonetheless, realists who wish to appeal to teleosemantics for a semantic proof of the external world must be capable of identifying these external norms, something that Millikan describes as highly fallible. Furthermore, because they can be aware of these norms only as these are internally represented, it would also be necessary for realists to verify that these internal representations accurately reflect the norms as they occur in the external world. But given that this is virtually the same stumbling block to realism found in meaning rationalism, it is concluded that teleosemantics is not likely to restore faith in this worldview. (shrink)

The current standard interpretation of Moore’s proof assumes Moore offers a solution to Kant’s famously posed problem of an external world, which Moore quotes at the start of his 1939 lecture “Proof of an External World.” As a solution to Kant’s problem, Moore’s proof fails utterly. Similarly, a second received interpretation imputes an aim of refuting metaphysical idealism that Moore’s proof does not at all achieve. This study departs from the received interpretations (...) to credit Moore’s stated aim for the proof Moore performed in his 1939 lecture that is to impose a counter-example to an explicitly stated presupposition of Kant’s famously posed problem of an external world. The outcome would therefore subvert Kant’s problem. There is not, however, any rival external world problem that Moore commends in place of Kant’s problem. (shrink)

In the first experiment, I exhibit unreliable judgment about the primeness or divisibility of four-digit numbers, in contrast to a seeming Excel program. In the second experiment, I exhibit an imperfect memory for arbitrary-seeming three-digit number and letter combinations, in contrast to my seeming collaborator with seemingly hidden notes. In the third experiment, I seem to suffer repeated defeats at chess. In all three experiments, the most straightforward interpretation of the experiential evidence is that something exists in the universe that (...) is superior in the relevant respects – theoretical reasoning (about primes), memorial retention (for digits and letters), or practical reasoning (at chess) – to my own solipsistically-conceived self. (shrink)

Contextualist responses to skepticism about the external world are inadequate, and we should prefer an invariantist response to skepticism. There are two kinds of contextualism---anti-theoretical and theoretical. Anti-theoretical contextualists argue that the principles on which skepticism depends are absent from our ordinary epistemic ways of thinking. So anti-theoretical contextualists conclude that the burden of proof is on the skeptic. But some argue that the principles on which skepticism depends are not absent from our ordinary ways of thinking. (...) The existence of this unresolved dispute suggests that anti-theoretical contextualists have not shifted the burden of proof to the skeptic. Anti-theoretical contextualists also fail to refute skepticism outright. Their primary argument here is one in which the notion of certainty plays a key role. But their argument is unsound on all significant uses of the word 'certain.' Thus, anti-theoretical contextualists have neither refuted skepticism nor shifted the burden of proof to the skeptic. ;Theoretical contextualism claims that the solution to skeptical puzzles lies in the fact that the standards for knowledge shift from context to context. Yet if theoretical contextualist solutions are to be adequate, they must explain how those standards shift. Unfortunately, theoretical contextualism fails to provide this explanation. This explanatory failure, along with the problems that face individual theoretical contextualist accounts, shows that theoretical contextualist responses to skepticism are inadequate. ;Even though contextualism fails, a Moorean invariantism---according to which the standards for knowledge are always low---allows us to know across contexts the things we ordinarily take ourselves to know. We should prefer this Moorean invariantism over contextualism. It stands on the same theoretical ground as the dominant contextualisms while still allowing us to explain how we know that certain skeptical hypotheses are false. Also, contextualism raises questions---for example, questions concerning how the standards for knowledge shift---that receive only inadequate answers. The Moorean invariantist account does not raise such questions. All of this suggests that the Moorean invariantist response to skepticism is better than any of its contextualist counterparts. (shrink)

The core idea of the ontological proof is to show that the concept of existence is somehow contained in the concept of God, and that therefore God’s existence can be logically derived—without any further assumptions about the external world—from the very idea, or definition, of God. Now, G.W. Leibniz has argued repeatedly that the traditional versions of the ontological proof are not fully conclusive, because they rest on the tacit assumption that the concept of God is (...) possible, i.e. free from contradiction. A complete proof will rather have to consist of two parts. First, a proof of premiseGod is possible. Second, a demonstration of the “remarkable proposition”If God is possible, then God exists. The present contribution investigates an interesting paper in which Leibniz tries to prove proposition. It will be argued that the underlying idea of God as a necessary being has to be interpreted with the help of a distinguished predicate letter ‘E’ as follows:\\). Proposition which Leibniz considered as “the best fruit of the entire logic” can then be formalized as follows:\) \rightarrow \, E)\). At first sight, Leibniz’s proof appears to be formally correct; but a closer examination reveals an ambiguity in his use of the modal notions. According to, the possibility of the necessary being has to be understood in the sense of something which possibly exists. However, in other places of his proof, Leibniz interprets the assumption that the necessary being is impossible in the diverging sense of something which involves a contradiction. Furthermore, Leibniz believes that an »impossible thing«, y, is such that contradictory propositions like \\) and \\) might both be true of y. It will be argued that the latter assumption is incompatible with Leibniz’s general views about logic and that the crucial proof is better reinterpreted as dealing with the necessity, possibility, and impossibility of concepts rather than of objects. In this case, the counterpart of turns out to be a theorem of Leibniz’s second order logic of concepts; but in order to obtain a full demonstration of the existence of God, the counterpart of, i.e. the self-consistency of the concept of a necessary being, remains to be proven. (shrink)

Many philosophers believe that the traditional problem of our knowledge of the external world was dissolved by Wittgestein and others. They argue that it was not really a problem - just a linguistic `confusion' that did not actually require a solution. Bruce Aune argues that they are wrong. He casts doubt on the generally accepted reasons for putting the problem aside and proposes an entirely new approach. By considering the history of the problem from Descartes to Kant, Aune (...) shows that analogous arguments create difficulties for the contemporary philosophical consensus. He makes it clear that the problem remains acute, particualarly for our understanding of scientific evidence. The solution he proposes draws upon contemporary philosophy of science and probability theory. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Reviewed by:Kant’s Transcendental Proof of RealismBrandon C. LookKenneth R. Westphal. Kant’s Transcendental Proof of Realism. New York: Cambridge University Press, 2004. Pp. x + 299. Cloth, $80.00.Westphal's book is a rich and exciting contribution to the field of Kant studies. Its claims run counter to much contemporary discussion of Kant's theoretical philosophy and indeed challenge some of Kant's fundamental doctrines, but the arguments are very compelling and (...) therefore likely to force us to rethink both the Critique of Pure Reason [CPR] and Kant's relevance to contemporary epistemology.The central point of this work is that, if we follow Kant's injunction to engage in reflection on our cognitive capacities, then we will be led not to Kantian transcendental idealism but to an unqualified realism about objects and events in space and time. The book's first three chapters are devoted to analyzing Kant's methodology and the much-overlooked idea of transcendental affinity. Westphal focuses on the Kantian duty of engaging in "transcendental reflection," which is "the action through which I make the comparison of representations in general with the cognitive power in which they are situated, and through which I distinguish whether they are to be compared with one another as belonging to pure understanding or to sensible intuition" (CPR, A 261/B 317). And he adds to this the more general methodological obligation of "epistemic reflection," or the duty to determine precisely our cognitive capacities and incapacities. If, then, we reflect on our representations, their origins in sensibility and the understanding, and on our powers to know things of ourselves and the world in general, then certain puzzles arise—puzzles that were confronted by Kant (and Hume and Hegel) but that have not received the attention they have deserved. Chief among these puzzles is our ability to identify single objects and events and track them in space through time. But, as Westphal is keen to point out, identifying any particular over time requires that we be able to re-identify that particular. Now, while this puzzle is addressed by Kant in the Transcendental Deduction and Analogies of Experience, it is important to see that there is a material condition necessary for the possibility of self-conscious experience of the world that is not fleshed out in great detail by Kant and seems to be completely overlooked in the literature on Kant, namely, "the presupposition of diversity in nature" and the homogeneity of its objects among themselves (CPR, A 657/B 685). In other words, the fact that we are able to associate our various sensations with each other at all (and thereby identify and re-identify objects) is due to their "transcendental affinity." And it is Westphal's contention that "on Kant's own principles, the transcendental affinity of the manifold of sensory intuition can only be reconstructed, but not constructed, by intellectual syntheses of the understanding" (91). Therefore, pace Kant, who held that only his transcendental idealism could explain the possibility of experience, Westphal argues that transcendental idealism runs afoul of many of Kant's own arguments and observations in the Transcendental Aesthetic and Transcendental Analytic and, more important, that transcendental affinity provides grounds for "realism sans phrase" (the author's phrase) about objects and events in space and time, and for the view that our mental states are determined by external objects. As Westphal puts it in his conclusion: "Kant's analysis of transcendental affinity is in fact a transcendental argument for mental content externalism" (266). [End Page 665]The second part of Westphal's argument revolves around a detailed examination of Kant's theses about transeunt causality and the nature of matter as expressed not only in the Critique of Pure Reason, but also in the Metaphysical Foundations of Natural Science and the Opus postumum. Roughly the problem is this: in order to have an adequately grounded metaphysics of nature, Kant needs not only the results of the Analogies of Experience, the transcendental causal thesis that every event has a cause, but also the metaphysical causal thesis that every physical event has an external physical cause. But, according to Westphal, in the Metaphysical Foundations... (shrink)

A critical discussion of selected chapters of the first volume of Scott Soames’s Philosophical Analysis in the Twentieth Century. It is argued that this volume falls short of the minimal standards of scholarship appropriate to a work that advertises itself as a history, and, further, that Soames’s frequent heuristic simplifications and distortions, since they are only sporadically identified as such, are more likely confuse than to enlighten the student. These points are illustrated by reference to Soames’s discussions of Russell’s logical (...) system and the place of the theory of descriptions in his ontological development. It is then argued that Soames’s interpretation of the point of G.E. Moore’s famous “proof” of an external world, while not straightforwardly undermined by the textual evidence, is nonetheless questionable, and plausibly overlooks what is novel in Moore’s discussion. This, it is argued, in his attempt to offer a common sense “refutation of idealism”, rather than (as is more commonly supposed) an anti-skeptical argument “from differential certainty”. (shrink)

What would it take for Hume to be an external world skeptic? Is Hume's position on knowledge sufficient to force him to deny that we can acquire knowledge of propositions about the external world? After all, Hume is extremely restrictive about what can be known because he requires knowledge to be immune to error. In this paper, I will argue that if Hume were a skeptic, then he must also deny a particular kind of view about (...) what is immediately present to the mind. I will argue that direct realisms—views that maintain that mind-independent things are immediately present to the mind—combine with Hume's position on knowledge to entail the negation of skepticism. So, despite his position on knowledge, Hume could still consistently reject skepticism, if he were to endorse direct realism. (shrink)

The current standard interpretation of Moore’s proof assumes he offers a solution to Kant’s famously posed problem of an external world, which Moore quotes at the start of his 1939 lecture “Proof of an External World.” As a solution to Kant’s problem, Moore’s proof would fail utterly. A second received interpretation imputes an aim of refuting metaphysical idealism that Moore’s proof does not at all achieve. This study departs from received interpretations to (...) credit the aim Moore announced for the proof Moore performed in his 1939 lecture. Moore’s aim was to impose a counter-example to a stated presupposition of Kant’s problem of an external world. Moore’s lecture nevertheless neither endorses a replacement for Kant’s problem nor acknowledges that an immediate implication of achieving his announced aim would subvert Kant’s famously posed problem of an external world. (shrink)

Many philosophers believe that the traditional problem of our knowledge of the external world was dissolved by Wittgestein and others. They argue that it was not really a problem - just a linguistic `confusion' that did not actually require a solution. Bruce Aune argues that they are wrong. He casts doubt on the generally accepted reasons for putting the problem aside and proposes an entirely new approach. By considering the history of the problem from Descartes to Kant, Aune (...) shows that analogous arguments create difficulties for the contemporary philosophical consensus. He makes it clear that the problem remains acute, particualarly for our understanding of scientific evidence. The solution he proposes draws upon contemporary philosophy of science and probability theory. (shrink)

The current standard interpretation of Moore’s proof assumes he offers a solution to Kant’s famously posed problem of an external world, which Moore quotes at the start of his 1939 lecture “Proof of an External World.” As a solution to Kant’s problem, Moore’s proof would fail utterly. A second received interpretation imputes an aim of refuting metaphysical idealism that Moore’s proof does not at all achieve. This study departs from received interpretations to (...) credit the aim Moore announced for the proof Moore performed in his 1939 lecture. Moore’s aim was to impose a counter-example to a stated presupposition of Kant’s problem of an external world. Moore’s lecture nevertheless neither endorses a replacement for Kant’s problem nor acknowledges that an immediate implication of achieving his announced aim would subvert Kant’s famously posed problem of an external world. (shrink)

In the last few years there has been a resurgence of interest in Moore’s Proof of the existence of an external world, which is now often rendered as follows:1 (I) Here’s a hand (II) If there is a hand here, there is an external world Therefore (III) There is an external world The contemporary debate has been mostly triggered by Crispin Wright’s influential—conservative —“Facts and certainty” and further fostered by Jim Pryor’s recent—liberal—“What’s wrong (...) with Moore’s argument?”.2 This debate is worth surveying with care because—so I shall contend—it will help us see that, in fact, it allows for an important view that, so far, hasn’t been explicitly considered. The critical survey will be the task of the next two sections, while, in the remaining.. (shrink)