GE Moore’s response to external world scepticism is, at least superficially, about as straightforward as philosophy gets. He argues from the existence of his own hands to the existence of an external world, reasoning as follows:

(1) Here is a hand.
(2) Here is another.
(3) External objects exist.

Of all the possible refutations of external world scepticism, this may appear to be not only the simplest but also the most inept. The sceptic, of course, will attempt to undermine Moore’s argument by questioning his entitlement to his premises; those who doubt the existence of the external world doubt the existence of hands, so Moore’s argument won’t be acceptable to any sceptic. It looks of though Moore has simply missed the point of the various sceptical arguments. There is a lot more, however, to Moore’s argument, than simple question-begging.

Given two apparently solid arguments leading to contradictory conclusions, what are we to do? If we are presented with two arguments, one for a claim and one against it, which argument ought we to accept?

One way of deciding between the arguments would be to examine their logical structures looking for points of weakness. If there are no points of weakness, though, then how are we to decide between them?

The answer to this question seems to be quite straightforward: we ought to reject the argument with the most questionable premises. Given two arguments with impeccable logic but contradictory conclusions, we ought to reject that which has the premises about which there is most doubt.

This, argues Moore, is the situation in which we find outselves. We are faced with two arguments: one a sceptical argument for the conclusion that we do not know whether there is an external world; the other an argument that appears to establish that there is an external world.

Whatever the logic of the sceptical argument, it cannot be superior to that of Moore’s argument for an external world, and so cannot be preferred on that ground. If we judge the arguments on logic, then, then we can only conclude that the external world exists.

Equally, whatever premises the sceptical argument makes use of, they will be less certain than the premises of Moore’s argument; that we have hands is about as certain as anything else. If we judge on plausibility of premises, then, then we can only conclude that the external world exists.

However we attempt to decide between sceptical arguments and Moore’s argument, then, we ought to reject the sceptical argument and favour Moore’s.