G. E. Moore

G. E. Moore was a British philosopher whose Principia Ethica launched 20th-century analytic ethics by arguing that 'good' is an indefinable non-natural property.

Moore argued that attempts to define 'good' in natural terms (pleasure, desire, evolution) commit the naturalistic fallacy; instead, goodness is a simple, non-natural quality known through direct moral intuition, and the most valuable things in life are personal affection and aesthetic enjoyment.