G. E. Moore
G. E. Moore maintained that "good" is an indefinable primitive, especially that it cannot be defined as something in the natural world, such as Bentham's pleasure, Mill's utility, the evolutionary theorists's survival, or even life itself. To identify good with something natural is called Moore's naturalistic fallacy. Moore's naturalism has much in common with that of David Hume. Hume claimed that we cannot derive "ought" (logically and rationally) from "is." This appears on the surface to be the same as Moore's naturalistic fallacy But Hume thought we could directly observe "ought" in an empirical and scientific study of human nature. So it appears that Hume was guilty of the naturalistic fallacy? Like many great thinkers, Hume is full of internal contradictions. Moore claimed he could prove the existence of the external world, that "there are in the Universe enormous numbers of material objects." One proof was to hold up his two hands and say, "Here is one hand" and "Here is another." Unfortunately, Moore's demonstration was merely empirical evidence for a theory, not a proposition capable of logical proof. Ludwig Wittgenstein did not doubt the obvious nature of Moore's demonstrations and the "truth" of his statements. But he did not regard the demonstrations as an adequate defense against someone arguing logically against them.