The scandal of natural law

The expression "natural law" refers to the basic principles of right and wrong that are true for everyone because they are rooted in the very nature of the created human person, and knowable to everyone because we are endowed with conscience and the power to deliberate. In principle, the natural law provides a point of contact, a common ground, among people of every culture -- although, as I've written, it is a slippery one." ~ J. Budziszewski, The Line Through the Heart: Natural Law as Fact, Theory, and Sign of Contradiction

Catholic thinkers are doing a lot of work in this field.