Full Idea
This really is a finger ...and you all know it. ...I can safely challenge anyone to give an argument that it is not true, which does not rest upon some premise which is less certain than is the proposition which it is designed to attack.
Gist of Idea
Arguments that my finger does not exist are less certain than your seeing my finger
Source
G.E. Moore (Some Judgements of Perception [1922], p.228), quoted by John Kekes - The Human Condition 01.3
Book Reference
Kekes,John: 'The Human Condition' [OUP 2010], p.18
A Reaction
[In Moore's 'Philosophical Studies'] This is a particularly clear statement from Moore of his famous claim. I'm not sure what to make of an attempt to compare a sceptical argument (dreams, demons) with the sight of a finger.