View source for Philosophy:Here is one hand

{{Short description|Epistemological argument by George Edward Moore}}
'''Here is one hand''' is an [[Philosophy:Epistemology|epistemological]] [[Philosophy:Argument|argument]] created by [[Biography:G. E. Moore|G. E. Moore]] in reaction against [[Philosophy:Philosophical skepticism|philosophical skepticism]] and in support of [[Philosophy:Common sense|common sense]].

The argument takes the following form:
* Here is one hand,
* And here is another.
* There are at least two external objects in the world.
* Therefore, an external world exists.

==Introduction==
G. E. Moore wrote "[[Religion:A Defence of Common Sense|A Defence of Common Sense]]" and ''Proof of an External World''. For the purposes of these essays, he posed skeptical hypotheses, such as "[[Philosophy:Dream argument|you may be dreaming]]" or "the world is 5 minutes old", and then provided his own response to them. Such hypotheses ostensibly create a situation where it is not possible to know that anything in the world exists. These hypotheses take the following form:

===The skeptical argument===
Where ''S'' is a [[Philosophy:Subject|subject]], ''sp'' is a skeptical possibility, such as the [[Philosophy:Brain in a vat|brain in a vat]] hypothesis, and ''q'' is a knowledge claim about the world:
:* If ''S'' doesn't know that not-''sp'', then ''S'' doesn't know that ''q''
:* ''S'' doesn't know that not-''sp''
:* Therefore, ''S'' doesn't know that ''q''

===Moore's response===
Moore does not attack the skeptical premise; instead, he reverses the argument from being in the form of [[Modus ponens|modus ponens]] to [[Modus tollens|modus tollens]]. This logical maneuver is often called a G. E. Moore shift or a Moorean shift.<ref name=":1">{{Cite web|url=http://www.iep.utm.edu/moore/#SH2d|title=From the Ontology of Cognition to Criteriology|last=Preston|first=Aaron|year=2004|website=Internet Encyclopedia of Philosophy|series=George Edward Moore (1873—1958)|access-date=April 13, 2016}}</ref> This is captured clearly in [[Biography:Fred Dretske|Fred Dretske]]'s aphorism that "one man's ''modus ponens'' is another man's ''modus tollens''".<ref>Dretske, F. (1995), ''Naturalizing the Mind'', Cambridge, Mass.: The MIT Press. {{ISBN|0-262-04149-9}}</ref> His response takes the following form:
:* If ''S'' doesn't know that not-''sp'', then ''S'' doesn't know that ''q''
:* ''S'' knows that ''q''
:* Therefore, ''S'' knows that not-''sp''

==Explanation==
Moore famously put the point into dramatic relief with his 1939 essay ''Proof of an External World'', in which he gave a common sense argument against skepticism by raising his right hand and saying "here is one hand," and then raising his left and saying "and here is another". Here, Moore is taking his knowledge claim (''q'') to be that he has two hands, and without rejecting the skeptic's premise, seeks to prove that we can know the skeptical possibility (''sp'') to be untrue.

Moore's argument is not simply a flippant response to the skeptic.  Moore gives, in ''Proof of an External World'', three requirements for a good proof: (1) the premises must be different from the conclusion, (2) the premises must be demonstrable, and (3) the conclusion must follow from the premises. He claims that his proof of an external world meets those three criteria.

In his 1925 essay "A Defence of Common Sense", Moore argues against [[Philosophy:Idealism|idealism]] and [[Skepticism|skepticism]] toward the external world on the grounds that skeptics could not give reasons to accept their metaphysical premises that were more plausible to him than the reasons he had to accept the common sense claims about our knowledge of the world that skeptics and idealists must deny. In other words, he is more willing to believe that he has a hand than to believe the premises of what he deems "a strange argument in a university classroom." "I do not think it is rational to be as certain of any one of these ... propositions".<ref name=":2">{{Cite web|url=http://www.calvin.edu/academic/philosophy/virtual_library/articles/derose_keith/responding_to_skepticism.pdf|title=Responding to Skepticism|last=DeRose|first=Keith|year=1999|website=Introduction to 'Skepticism: A Contemporary Reader'|publisher=Oxford UP|access-date=April 13, 2016}}</ref>

==Objections and replies==
Some subsequent philosophers (especially those inclined to skeptical doubts) have found Moore's method of argument unconvincing.<ref name="podgorski">{{Cite web|url=http://thegemsbok.com/art-reviews-and-articles/friday-phil-radical-skepticism-ge-moore/|title=Intuition All Alone: On G.E. Moore's Tempting but Insufficient Answer to Radical Skepticism|last=Podgorski|first=Daniel|year=2015|website=The Gemsbok|access-date=April 13, 2016}}</ref>

One form of refutation contends that Moore's attempted proof fails his second criterion for a good proof (i.e. the premises are not demonstrable in the required sense) by pointing out the difference between demonstrating the [[Perception|perception]] that his hands exist and demonstrating the [[Philosophy:Epistemology|knowledge]] that his hands exist. Moore may be doing the former when he means to be doing the latter.<ref name="podgorski" />

Another form of refutation simply points out that not everyone shares Moore's intuition. If a person finds the skeptical possibility ''sp'' more intuitively likely than the knowledge claim ''q'', then for that person Moore's own defense of [[Intuition|intuition]] provides a basis for their skepticism.<ref name="podgorski" />

[[Biography:Ludwig Wittgenstein|Ludwig Wittgenstein]] offered a subtle objection to Moore's argument in passage #554 of ''[[Philosophy:On Certainty|On Certainty]]'' (see [[Philosophy:Here is one hand#Legacy|below]]). Considering "I know", he said "In its language-game it is not presumptuous ('nicht anmassend')," so that even if P implies Q, knowing P is true doesn't ''necessarily'' entail Q. Moore has displaced "I know.." from its language-game and derived a fallacy.

==Legacy==
Appeals of this type are subsequently often called "Moorean facts".<ref name=":1" /> "A Moorean fact [is] one of those things that we know better than we know the premises of any philosophical argument to the contrary".<ref name=":2" />

Moore's claim to ''know'' such facts had "long interested"<ref>{{cite book|last=Wittgenstein|first=Ludwig|title=On Certainty|location=New York|publisher=Harper and Row|year=1969|isbn=0-06-131686-5|page=vie|url-access=registration|url=https://archive.org/details/oncertainty00witt}}</ref> [[Biography:Ludwig Wittgenstein|Ludwig Wittgenstein]].
His last writings in the six weeks before his death in 1951 were an attempt to respond comprehensively to Moore's argument, the fourth time in two years he had tried to do so. His notes from the four periods were collected and translated by his literary executors and published posthumously as ''[[Philosophy:On Certainty|On Certainty]]'' in 1969.

==See also==
* Samuel Johnson, who is said to have kicked a rock on learning of [[Biography:George Berkeley|Bishop Berkeley]]'s denial of matter, [[Philosophy:Appeal to the stone|declaring "I refute it thus!"]]
* [[Biography:Diogenes|Diogenes]], who is said to have walked away upon hearing a philosophical argument denying the existence of motion, intending to prove without utterance that motion does indeed exist.
* In [[Biography:Leo Tolstoy|Leo Tolstoy]]'s War and Peace, [[Determinism|determinism]] is refuted as: “You say: I am not free. But I have raised and lowered my arm. Everyone understands that this illogical answer is an irrefutable proof of freedom.”
* {{section link|Nonsense|Disguised Epistemic Nonsense}}

==References==
<references/>

==External links==
* Kelly, Thomas. "[http://www.princeton.edu/~tkelly/papers/Moore.pdf Moorean Facts and Belief Revision, or Can the Skeptic Win?]". Princeton University, in John Hawthorne (ed.), ''Philosophical Perspectives'', vol.19: Epistemology, 2005.

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[[Category:Skepticism]]
[[Category:Concepts in epistemology]]

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