The point isn't about the external world. It's about deduction vs induction, the point is about axioms. Axioms are arbitrary, thus deductive reasoning is ultima

The point isn't about the external world. It's about deduction vs induction, the point is about axioms. Axioms are arbitrary, thus deductive reasoning is ultimately arbitrary. If there is a hand then everything else falls out deductively. Using induction, it's trivially true that there is a hand. Using deductive reasoning to prove an inductive proposition is ultimately a waste of time, using inductive reasoning to create a correct framework for deductive reasoning is ultimately unknowable. Both of these together is how we live our lives and create our standard model, which is ultimately imprecise at best, and wrong at second best. This is Moore's point, that we are wasting our time trying to deductively prove the existence of an external world when it's trivially provable. We may not get accurate axiomatic framework, but we can never get that anyway. Much of the point of philosophy is properly delineating between these two methods of reasoning. Much of analytic philosophy is finding areas where language blurs the two.