Reason lies between the spur and the bridle.– Old English Proverb
If there is justification in the naturalists' dismissal of objective moral theories, it is something we still must search for. The goal of the next two chapters is to locate the nonnatural element in such theories. Ultimately I will argue that it is a certain thesis about norms and reasons for action to which naturalists object, but to which moral objectivists are committed.
To identify this thesis, however, I will need to do a lot of philosophical spadework. In Chapter 2, I will show that moral objectivism is characterized by a commitment to the idea that there are moral norms. I will then analyze the concept of a norm, showing how norms give us reasons of all sorts – to act, believe, feel, and decide, among others. Finally, I will discuss the nature of reasons and the various philosophical issues that can be, and often have been, raised to understand, identify, and defend them. I will argue that the most important identifying characteristic of a reason is its “authority” – where this is something quite different from whatever motivational efficacy the reason might have.
Chapter 3 builds on this analysis by developing two theses about the nature of this authority, one of which moral objectivists accept with respect to moral reasons, and which is inconsistent with the commitments of naturalism, the other of which is acceptable to the naturalist, but incompatible with moral objectivism.