An excellent, clear discussion of official Roman Catholic moral method with good discussions of Aquinas, natural law (71-86 and then on Grisez and new natural law at 93-118), conscience (57-65), papal teaching etc. Note there are earlier, less comprehensive editions.

Here -- carefully documented, footnoted, and indexed -- is not only what the Church teaches but also why it is obligated to do so. This updated and expanded edition of a text widely used in colleges, universities, and seminaries (as well as in high schools and parish religious education programs), offers the latest Catholic teaching on moral theology, including: moral theology; human dignity, free human action, virtue, and conscience; and natural law, moral absolutes, and sin. Read why -- and how -- living what the Church teaches can transform hearts, minds, and souls.