 Ross suggests most errors in our moral thinking concern media axiomata – or middle principles or rules – rather than fundamental moral principles (FE 190; RG 20–21n1). However, he seems at times to consider reflective inquiry with the potential for revisions of a more radical nature. He suggests, for example, inquiry into the ‘historical origin of…[our moral] beliefs and practices’ may show ‘the most strongly felt repulsions towards certain types of conduct are relics of a bygone system of totems and fetishes, their connexion with which is little suspected by those who feel them’ (RG 13). An inquiry of this kind may lead to significant revision of even aspects of moral thinking thought to be fundamental (Singer 2005). 