他最初的理论是区分「义务性道德（Morality of duty）及「期待性道德（Morality of aspiration），两者都背负了社会制度计划与运作的责任，前者是为任何有目的社会意图设下规矩，后者则是为这些社会意图指引方向。
权威例句
1.
It rejects the aspirationof political liberalism to neutrality among conceptions ofmorality while simultaneously retaining its spirit by sectioning off social morality from other normative domains.