Talk:Here is one hand

In the "Effect" section of this article is the following entry:

"Although perhaps not a supplement to Moore's argument, it has been mentioned in undergraduate philosophy classes that Moore famously mistook his own sense perception once in a lecture. Whereby he claimed 'there is a window' pointing at a curtain in a gymnasium, but when a student pulled the curtain away it was merely a wall. Whether this is a philosophical urban legend or not, there is little doubt that optical illusions and hallucinations can cause unreliable sense perceptions."

I don't believe "optical illusions" and "hallucinations" are accurate terms in that scenario. He did not believe he SAW a window, but rather he ASSUMED there to be a window. There was no illusion or hallucination, either of which would mean he saw a glass-paned window that did not in fact exist. He saw only curtains, and assumed the nature of what lay behind. I suppose it is true, then, that "'false assumptions' can cause unreliable sense perceptions."

  THANK YOU!!! - --Carlon 03:00, 7 August 2007 (UTC)

The formalising of Moore’s argument

Isn't the argument better described as it actually appears? As O, ~H -> ~O |- H?

Moore's hands....

What an apologist! --Carlon 03:00, 7 August 2007 (UTC)

Remind me to tidy this page up after fiddling with https://docs.google.com/document/d/1XFdpTPbtxY2sAPl5c8u9yVTQ72B9NPxxX5nAKlJ5i6k/edit?usp=sharing or I'll never remember. 89.240.133.40 (talk) 10:38, 26 March 2019 (UTC)

Question

Moore's argument flips the modus ponens structure into a modus tollens:

• If A then B.
• Not B.
• Therefore not A.

I am missing something here... Shouldn't that be Iff (=If and only if) A then B ? Otherwise, Not B does not necessarily imply not A. After all, 'Not B' could have come about in other ways, no?--Goodmorningworld (talk) 22:39, 15 October 2008 (UTC)

a implies b is false when b is false and a is true. therefore when b is false a must be false

(A->B) being true is equal to (B is true or A is false) being True Therefore if (A->B) and B is false then A is false (because if A is True and B false then (A->B) is False or that would break the fact that A->B is True). And A True Iff B True would basically mean A <=> B (A->B (the if part) + A<-B(the only if part)) A keyboard is not the best to convey this i guess.... —Preceding unsigned comment added by 81.80.239.162 (talk) 15:40, 27 November 2008 (UTC)

It is correct as it is. By (1) and contraposition, one gets ¬B→¬A. From (1') and (2), (3) follows by Modus Ponens. Deleet (talk) 07:47, 15 November 2012 (UTC)

So...

What's the sound of it clapping? Totnesmartin (talk) 09:53, 7 August 2010 (UTC)

I've seen my hand in dreams...

How is this valid? I've seen my hand in dreams, and with the help of mirrors i could show i have more than 2 hands. How is using your senses that have been proven to not be reliable to recognize the existence of hands proof that they do exist? --TiagoTiago (talk) 04:01, 3 November 2011 (UTC)

It isn't valid. The existence of drug-induced hallucinations invalidates the argument.173.72.63.70 (talk) 21:33, 7 June 2012 (UTC)Hans Wurst

Many years before Moore was born, Descartes wrote, in his Meditations, I, 12: "I will suppose…that some malignant demon, who is at once exceedingly potent and deceitful, has employed all his artifice to deceive me; I will suppose that…all external things, are nothing better than the illusions of dreams, by means of which this being has laid snares for my credulity; I will consider myself as without hands…or of any of the senses, and as falsely believing that I am possessed of these…."Lestrade (talk) 22:28, 8 June 2012 (UTC)Lestrade

Needs rewrite

This article is wrong about what Moore was arguing against. Cf. http://plato.stanford.edu/entries/moore/#6. Quoting SEP:

The significance of this performance has been debated ever since Moore set it out. It is commonly supposed that Moore here sets himself to refute philosophical skepticism; and that his performance, though intriguing, is unsuccessful. But this interpretation is incorrect: Moore's avowed aim is to prove the existence of an external world, not to prove his knowledge of the existence of an external world. Moore himself set this out clearly in a subsequent discussion of his lecture:

'I have sometimes distinguished between two different propositions, each of which has been made by some philosophers, namely (1) the proposition ‘there are no material things’ and (2) the proposition ‘Nobody knows for certain that there are any material things’. And in my latest British Academy lecture called ‘Proof of an External World’ … I implied with regard to the first of these propositions that it could be proved to be false in such a way as this; namely, by holding up one of your hands and saying ‘This hand is a material thing; therefore there is at least one material thing’. But with regard to the second of the two propositions …. I do not think I have ever implied that it could be proved to be false in any such simple way … (‘A Reply to my Critics’ 668)'

If he knows that his hand proves that material things exist, then he knows material things exist. Therefore, he knows that the second proposition is false. 212.159.77.63 (talk) — Preceding undated comment added 18:43, 27 February 2014 (UTC)

I might rewrite it later, but someone else can do it as well. Deleet (talk) 07:51, 15 November 2012 (UTC)

Origin of 'Hand Waving' as an inadequate idea of Proof ?

I have suggested in talk:Handwaving that Moore's 'proof' might be the origin of the term 'handwaving' as a 'glossed over' or superficial approach to proving an idea or theorem. I am not sure whether this is correct, but I can't find any references to handwaving as a method of 'proof' earlier than 1939, when Moore used it in his lecture.--TonyFleet (talk) 10:55, 16 June 2013 (UTC)

In regards to the responses

Why is there a response from a random article? There should only be responses from actual philosophers. — Preceding unsigned comment added by 108.34.164.41 (talk) 06:54, 22 February 2018 (UTC)

By what criterion are you determining who is an "actual" philosopher? 'People whose names you already know' and 'not published on a website' are not valid criteria. I've read all of the current linked sources, and there isn't a single one that doesn't offer a sound and professional philosophical interface with Moore's ideas. 2600:1700:8450:EF50:ECA8:42D8:3B1:73D6 (talk) 09:04, 22 February 2018 (UTC)

A Commons file used on this page has been nominated for deletion

The following Wikimedia Commons file used on this page has been nominated for deletion:

• George Edward Moore.jpg

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 01:12, 26 December 2018 (UTC)