 Mackie himself is relatively unclear on this issue. Some take him to be concerned primarily with the motivational commitments of moral discourse – that moral discourse entails the truth of motivational internalism, (roughly) the view that genuine moral beliefs entail motivation to act in accordance with those beliefs (see Joyce 2001: ch. 1). David Brink argues that Mackie is unclear between two potentially problematic entailments of moral discourse: motivational internalism, and reasons internalism – the view that moral obligation entails reasons for action (Brink 1984). Jonas Olson argues that Mackie actually argues for the queerness of four distinct features of moral discourse: motivational internalism, a sui generis epistemic faculty, the supervenience of the moral on the non-moral, and finally, the irreducible normativity of moral facts (Olson 2014: chs. 5 and 6).