U, as moral standard, must provide motivating reason for action. Typically, actions lack moral motivation. Inculcation through law and education needed because moral motivation not natural. U cannot serve as principle of morality. Two Responses 1.
Moral standards do have to supply motivating reasons and U does so.
Claim that adequate principle of morality must morally motivate is false 2. U can provide justifying reason without supplying motivating reason 3. Here Mill is an externalist with regard to moral motivation 4. U is a criterion of moral justification for action, not an explanatory device 5. There is a natural and historical basis for motivation by U 3.