Jane Addams meets Friedrich Nietzsche
My first thought was to ask how social science fits into Leiter-Nietzsche's contrast between progressive natural science and sophistic moral philosophy. Social science seems to have made little more progress than moral philosophy -- foundational debates between Marxists and neoclassical economics, for example, perisist even if disguised by the disciplinary barrier between economics and sociology. Indeed, social scientists have it worse than moral philosophers in that they can't even agree on what would count as progress in their field (the basic positivist-interpretivist divide). But surely it would be absurd to say that this must be because the facts social scientists are pursuing do not exist, that there is no such thing as "how a society works."
Then Jane Addams comes in. A crucial assumption in Leiter's paper is that the activities of philosophers thus far -- mostly "armchair" conceptual analysis, deductive theorizing, and intuition-probing -- are methods that would lead to discovery of moral truths if such things exist. Their failure is then a telling indictment of the whole project. But the philosophical school of Pragmatism -- represented best in this context by Addams and John Dewey -- would hold that such theorizing is the wrong way to go about advancement in the moral field. The natural sciences, pragmatists would note, were stuck in a rut much like moral philosophy's current one up until the Enlightenment. During that period they worked on the armchair model, deriving theories of physical laws from deductive reasoning and interpretation of ancient authorities. Hence, for example, the pre-Kepler inability to consider that planets might orbit in imperfect ellipses rather than perfect circles. If the theories, moral as well as scientific, were not as diverse as modern moral philosophy, it's only because of the existence of the Church as an institution with a vested interest in maintaining the appearance of unified truth. What allowed the natural sciences to become genuinely progressive was the adoption of the experimental method, developing theories through engagement and experience with the world being studied. Pragmatists propose that moral progress can only come by incorporating the experimental method into moral study****. Indeed, Addams says she learned the importance of the experimental method experimentally, as the first lesson that came out of her experience running the Hull-House charity.
We can talk of a few general advances in moral philosophy. Though the specifics remain hotly contested, it is generally accepted now that any acceptable moral theory must condemn slavery, for example, must reject divine natural law, and must be democratic in some form. These advances were arrived at not by Cartesian cogitation but by the give-and-take of reflection and practice in actual societies that found the contrary doctrines, popular as they once were, to be unworkable responses to the real problems we encounter.
A variety of reasons may be proposed for why the natural sciences could sieze on the experimental method and be carried so far by it whereas moral philosophy has lagged. The most obvious is difficulty. Compared to human activity, physical processes are relatively tractable in scale, controllability, and manipulability. It's easy to put a plant in a box and pour fertilizer on it to see what happens, but it's difficult to change the system of cooperation in a neighborhood to see what happens. Truly applying the experimental method to moral study requires much broader cooperation and much more time and resources (making it ironic that while cutting-edge science is typically practiced in teams numbering in the dozens, philosophy papers are still mostly the product of a single author).
Another important factor is the historical origin of the fields. The era of productive and progressive natural science is closely linked to its marriage with technology. The desire for machines and processes with which to manipulate nature exerted strong pressure on natural science to "get it right" in response to specific practical problems, while suiting the competitive work of individuals or small teams that, as mentioned above, is more feasible in the natural sciences than the moral ones. On the other hand, moral philosophy is a child of theology. While submisison to scripture and deductively asking what a perfect being would require have been found wanting as routes to moral advancement, the image of the authoritative, foundational macro-theory has continued to hang over moral philosophy.
None of this is to say that experimental moral learning hasn't occurred -- talk to any acivist involved in a serious moral struggle. But the learning still happens mostly piecemeal and as a personal or particular-group by-product. It hasn't been institutionalized, systematized, and ratified by the academy the way scientific advances have.
It should be said that the distance between Addams and Nietzsche may not be quite so great as I make it out to be*****. I'm no Nietzsche scholar, nor have I read Leiter's other work that may clarify this, but Leiter does at times refer to Nietzsche's critique as being directed against "morality in the pejorative sense" or a "Platonic" conception of moral truths. This leaves open the question of exactly how much of the normative field Leiter-Nietzsche intend to debunk. The idea of normative statements in the sense of "good for" -- which Leiter insists Nietzsche accepts -- has a pragmatist flavor to it. But Nietzsche is commonly understood, in his concern to free great men to exercise their will to power, to have a far more egoistic interpretation of what kind of normativity is left than the explicitly social and democratic ideals of the pragmatists.
*The link takes you to a draft paper -- I'm responding to the Dec. 10 2008 version. Doubtless elements will change before it's officially published.
**One might say that it's simply that no moral truths are knowable -- though in practice that amounts to the same thing unless one can give a clear specification of the conditions under which the epistemic barrier might someday be surmounted.
***Though if this is true, it seems unlikely that Leiter's paper would make much headway, seeing as it merely states an argument rather than changes the social context.
****I would point out here that the pragmatist experimental method -- of trying out the implications of various moral theories and seeing what they amount to in practice -- is different from the field of "experimental philosophy," which attempts to disprove certain armchair philosophical claims by showing that their presuppositions are not in fact shared by ordinary people.
*****I was interested to note recently that Pierre Bourdieu -- who has a basically pragmatist orientation despite rarely having the term applied to him -- makes frequent, approving references to Nietzsche.