Open question argument

Open question argument: Whenever identity of the good with a natural property is claimed, the question of value that always remains is – but is it really good? (e.g., “pleasure”).

Source: What is Good? What is Bad? The Value of All Values across Time, Place and Theories’ by John McMurtry, Philosophy and World Problems, Volume I-III, UNESCO in partnership with Encyclopedia of Life Support Systems: Oxford, 2004-11.