The title of this essay is not meant to impugn Humeans; it is only meant to recognize a kind of person that some Humeans might have thought impossible, namely, someone with a full complement of other-regarding sentiments who possesses those “useful” natural virtues (such as benevolence) of the sort described by Hume but who nonetheless behaves like a “knave” (to use Hume's own word) in situations where he can exploit another with impunity. In the Second Inquiry, Hume regards such knavishness as resulting from of a lack of concern for, and integrity with respect to the treatment of, one's fellow human beings. Hume represents the knave's point of view as follows:

THE PROJECT

For many years now, an interesting conflict has raged within contemporary philosophy. On one side of the conflict are “objectivist” moral and political philosophers, who believe in and accept the existence of distinctive (and irreducible) moral “values” – words that in this conflict have been used to cover a variety of normative notions fundamental to moral and political theories – for example, rights, duties, goods, and reasons for action. These philosophers maintain that moral judgments that involve values can be true or false, and that these moral facts cannot be reduced to the sort of facts recognized by scientific theories. In that sense, they believe there are value-laden, nonreducible moral judgments that are objective. On the other side of this debate are the “naturalists,” who insist that the world, as our best scientific theories portray it, does not and cannot contain values. Since values are the stuff of the theorizing of the moral objectivists, it follows from the naturalists' position that there can be no uniquely moral facts. Hence they deny the possibility that there are value-laden, nonreducible moral judgments that are objective.

In the preceding chapters, I have argued that a theory of instrumental reason of the sort that science requires must be informed by norms that have objective authority, at least some of which concern the structure and content of human good. If these arguments are right, however, they still do not in and of themselves vindicate any objectivist moral theory. The moral skeptic can fall back on the following argument: Alright, I will accept that I have objectively authoritative norms lurking in my theory of rationality, but I do not believe that there are objectively authoritative moral norms. Norms of rationality are real; norms of morality are not.

This response raises an important question: how does one go about showing that any given norm is “real” – that is, a norm that genuinely has objective authority? Moral theorists have worried about this question in a variety of ways, but few outside of moral theory have done so, because, I suspect, they haven't believed that they had to do so.

Although this book seeks to show that the naturalists are wrong to criticize the normativity in moral theory, nonetheless in Part I, I shall be taking the naturalists' side, identifying what it is about the moral objectivists' norms that cannot, in the naturalists' view, pass “scientific muster.” This involves explaining what “scientific muster” is supposed to be and why a theory is commonly thought to be disreputable unless it passes it.

Surprisingly, however, this is a difficult project. In this chapter, I will review a variety of ways that naturalists have tried to show the unscientific nature of objective moral norms, none of which I shall argue is successful. It is remarkable that objectivist moral theorists have been so much on the defensive in recent years, given that the naturalists' arguments against their theories have been incomplete, or imprecise, or have, in various ways, begged the question at issue.

I will then spend the next two chapters developing a more successful argument on behalf of the naturalists. Once we are clear about the unnatural component within objectivist moral theories, we will be in a position to look for it in the theories of the naturalists in Part II.

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.

Thesis of this book: Naturalist moral skepticism, based on a naturalist theory of reasons, fails. Naturalizing the reasons that the naturalist requires for his own conception of practical reason and scientific methodology fails. The same nonnatural “authority” of moral reasons attends the naturalist's instrumental reasons; the same reflection on the nature of human good that is required in order to live a moral life is also required to live an instrumentally rational life. The naturalist-friendly conception of instrumental reasoning as consequentialist turns out to be inadequate. And if instrumental reasoning must be construed along nonconsequentialist lines in order to understand what we do, the claims by moral theorists that moral reasoning is nonconsequentialist become yet more plausible.

What do we do now? The death of one conception of reasons clears the way for the birth of another. The naturalist conception seemed simple, elegant, and commonsensical, but since it turned out to be none of these things, how do we construct a theory of reasons that is more successful? What are the criteria that we should use? What vestiges of the naturalist program, if any, should we remain wedded to?

There is, in my view, considerable virtue in the naturalist insistence on developing a theory that resists nonsense and flights of metaphysical fancy.

Israel Scheffler once told me that every time he wrote a book, he would swear it would be his last. Any author knows the feeling – books take too long to write, the arguments and the prose never seem good enough, and when one is all done, the enormity of all that is still wrong with the final product hits home. Still, authors are ever hopeful that their contributions will be of some use, and I am no exception. I have aimed to write a book that does not so much attempt to persuade, as to dissuade – I wish to shake readers loose from the grip of a conception of the world that threatens our ability to act both rationally and reasonably.

In the process of constructing a work that attempts to rattle those who read it, I have been the recipient of much help, often from people who are quite opposed to this project. I am very grateful for their generous support and probing criticisms. In particular, I would like to thank Julia Annas, John Broome, Tom Christiano, David Copp, Ron Milo, Ken O'Day, John Pollock, Joseph Raz, John Roemer, Robert Sugden, and Bruno Verbeek. I also owe much to the graduate students attending my seminars at the University of California at Davis and the University of Arizona, in which portions of this book were presented.