Fact/value distinction

Fact/value distinction: a conventional distinction between that which is and that which ought to be which is rendered dubious by the ‘is’ itself typically conforming to habituated ought-prescriptions.

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.