Some thinkers hold that whatever brings pleasure to people is good, and vice versa, and that whatever brings pain is evil, and vice versa. This, however, is obviously untenable. The concepts of good and evil are contradictory, whereas those of pleasure and pain are not. Clearly it is possible to be in a state of pleasure and pain at once. The argument challenges a claim that two pairs of concepts are equivalent by claiming that ['"good" does not apply to any of the same things that "pleasure" does', '"good" and "evil" do not bear the same relationship to one another that "pleasure" and "pain" do to one another', '"pleasure" and "pain" possess a property not possessed by any other possible pair of concepts', 'it is merely accidental that "pleasure" and "pain" are applied in the same way as "good" and "evil" are applied']