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Why did G.E. Moore’s proof of the external world focus on showing his hands?

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Marble bust of Aristotle with a beard and draped robe, showing detailed facial features and wavy hair, set against a dark background. — metaphysics Detail of a Roman copy (2nd century bce) of a Greek alabaster portrait bust of Aristotle (c. 325 bce); in the collection of the Museo Nazionale Romano, Rome.

In his 1939 lecture, "Proof of an External World," G.E. Moore used his hands as a simple, direct demonstration to assert the existence of an external world. By displaying one hand and stating, "Here is one hand," and then the other, saying, "and here is another," he provided a concrete example of objects that he and his audience knew to exist.12

Moore’s intent was not necessarily to offer a complex metaphysical argument, but rather to challenge the skeptical demand for a proof of the external world. By presenting a scenario that satisfied the logical requirements for a proof, he raised a pointed question: why should such a trivial, common-sense exercise not be accepted as a valid proof of an external world?12

This approach was consistent with Moore’s broader "common-sense philosophy," which held that certain propositions about the world are known with certainty and that any philosophical system contradicting these basic truths could be rejected.3