Moore’s first major article was “The Refutation of Idealism,” which was published in Mind in 1903. In it he argued that no idealist or skeptical argument was as convincing as common sense beliefs that the world is real, and that, therefore, idealism and skepticism can just be dismissed. Moore became famous for “proving” the existence of the external world with his legendary “two hands argument” (derived from his 1939 “Proof of an External World” argument against skepticism concerning the existence of the external world.)

Moore said that by raising his right hand and saying, “Here is a hand,” and then raising his left and saying, “And here is another,” the skeptical position was disproved. This was not as “off hand” a dismissal as it seems. Moore’s premise was that he knew he had two hands, from which it followed that the external world existed, from which it followed that there was no ground for the skeptic’s doubt about its existence.