Throughout this discussion, we have worked our way down a metaethics decision tree. I have made a case for a relativist cognitivist sentimentalist sensibility theory. Admittedly, each of my arguments is only a first pass, and much more could be said for and against these positions. Many of the empirical findings that I have described are preliminary. My main goal here is not to make a decisive case for any position in metaethics. Rather, I am pleading for the relevance of empirical methods in doing this traditionally philosophical work. Moral philosophy is undergoing a process of naturalization. This has been felt most strongly in normative theory (e.g., the debate about the status of character in virtue ethics) and moral psychology (e.g., questions about how deontological and consequentialist judgments are made). I hope to have shown that the empirical work also bears directly on metaethical questions—questions about what, if anything, is the source of moral truth.
Empirical work cannot replace philosophical toil. We need philosophy to pose questions and identify possible theories. Experimental design is itself a kind of philosophical reasoning, and it takes considerable argumentation to move from data to theory. Naturalization is supplementation, not usurpation. But it is not just supplementation. The empirical arsenal may just be our best hope for adjudicating philosophical debates. Reflection can delineate the logical space, but we need observation to locate ourselves therein. Philosophers have always relied on observation, in some sense, but scientific methods allow us to observe processes that are unconscious, inchoate, or distant in space and time. Empirical studies can test the content, prevalence, and malleability of intuitions, and they can also tell us where our intuitions come from—a question of central metaethical concern. We should embrace any tools that help us resolve the questions that we are employed to answer. A century ago, there was a linguistic turn, and philosophers began to treat traditional philosophical problems as amenable to semantic analysis. Around the same time, the boundary between philosophy and psychology was still blurred, and journals such as Mind published articles that we might now classify as psychological. Such crossovers fell out of fashion, however, and it has taken a century to get back to this incipient moment. With the linguistic turn, Anglophone philosophers became convinced that we should all learn logic because it would help us make progress. Logic did help, and it did not undermine philosophy. Now, we can encourage all philosophers to learn about methods and results used in the relevant social and physical sciences. The payoff of this naturalistic turn may be vastly greater than the linguistic turn. Science, not formal logic, is positioned to tell us whether morality is a human construction.
Acknowledgments
This discussion has benefited immeasurably from the feedback of anonymous referees and from Ying-Tung Lin, Jessica McCormack, Thomas Metzinger, and Jennifer Windt. I am grateful for their close reading and helpful suggestions.