According Moore, all naturalistic analytic definitions of “good” fail, committing what he called “the naturalistic fallacy”. To show all naturalistic analyses of goodness fail, Moore presented the “open-question argument”. The basic idea is that if a definition of “good” is correct, a morally competent person could not sensibly question whether something satisfying the definition is good. Consider a definable term: a triangle is a closed plane figure with three angles. No person who understands