Moore's Refutation of Skepticism

[public hermit]

Famously, G.E. Moore held up his hand in front of the class and declared, "Here is a hand." And, by that declaration, Moore refuted epistemic skepticism.

What was he refuting?

• If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).
• S doesn't know that not-sk.
• Therefore, S doesn't know that q (she has a hand). - modus tollens

What was Moore declaring?

• If S knows that q (she has a hand), then S knows that not-sk (skepticism is false).
• S knows that q.
• Therefore, S knows that not-sk (skepticism is false). - modus ponens

Does that argument work? Can I just raise my hand, and wave away all the brain-in-a-vat, Cartesian-daemon possibilities?

Here is one hand - Wikipedia

en.wikipedia.org