Moore and Wittgenstein On Certainty

Many philosophers (and others) have argued that we cannot really know whether anything exists outside our minds.  This is called skepticism about the external world.  Under the influence of Kant and Hegel, many others have argued that all that exists are minds and their contents, that physical objects exist only in the mind.  This is called idealism.  The British philosopher G. E. Moore (1873-1958) tried to refute both skepticism and idealism.

What does 'outside our minds' mean?  Surely it means outside the minds of human beings, i.e. of physical beings that we sense.  So it looks as though the very idea that the external world might not exist could be self-defeating.   In explaining what the idea means we have to refer to the very things it calls into question.  This is at least embarrassing for idealists and skeptics.

Perhaps more importantly, what is more certain, that I have hands or that the arguments for idealism and skepticism are flawless?  Surely nothing is more certain than the existence of the hands I see before my face.  So it is irrational to deny their existence on the grounds of some argument whose premises are less certain. 

Wittgenstein was not an idealist or skeptic, but he thought that thee was something wrong with Moore's refutation.  He also thought that Moore was on to something.  Wittgenstein suggests that proving some claim to be true is an activity that belongs to a certain kind of context,and that outside that context it makes little sense to claim that one as proved something (e.g. the existence of my hands, or the external world).  Proof implies doubt, and Moore's 'proof' depends on the fact that the certainties he reminds us of are not in doubt. 

Idealism is not so much false as nonsensical.  It is not a denial of the reality of physical objects nor a claim about the existence of psychic powers.  It is a claim about the 'metaphysical status' of physical objects.  But what is that?  It has no practical significance whatsoever.  As an idea without use it is surely also without meaning.

Skepticism can be like this too.  It would be hard to know (in normal circumstances) what to make of any claim to be in real doubt as to whether I have two hands.  Someone making such a claim would seem to be either pointlessly 'philosophical' or else mad.  The pointless claim is nonsense (i.e. not really a claim at all, any more than saying 'wibble wibble' is making a claim about the world).   The mad claim is not so much a claim as a symptom of mental illness.  But if someone chooses to be skeptical to a less-than-insane degree, being unusually cautious about things, then this is a way of living, and philosophy will not show it to be wrong.   Philosophy, for Wittgenstein, does not tell us how to live our lives.