 The idea of a prima facie duty or obligation had not been fully clarified before Ross, either by defenders of deontological theories (though see Price 1787, 152, 167, 168 and Prichard 2002, 77–83) or their critics (including Moore 1903, 1912; Rashdall 1907, 1913; and Sidgwick 1907). Ross’s introduction of the notion of a prima facie obligation constitutes a major advance in the dispute between utilitarians and non-utilitarians. It paved the way for a moderate deontology. Ross’s innovation is crucial to avoiding cases thought problematic for absolute deontology in which obligations conflict and one is unable to avoid doing what is all things considered wrong (FE 83–86).