Well, what about knowledge apart from science? Can reasoning about morality be reduced to a form of science? Can mathematics? Or the multiple discourses of everyday life, from cooking to religion, that might be nonscientific but no less legitimate on their own terms? Even many naturalists leave these alone, resisting what they view as scientism or reductionism—particularly naturalist philosophers of a neopragmatic bent, such as Kai Nielsen. Pragmatists still shun metaphysics, but then, what if metaphysics is also a perfectly legitimate discourse on its own terms?
Let me start with mathematics, as it is a perennial temptation to metaphysics of a very straightforwardly Platonic sort. Indeed, many mathematicians think of their own work in Platonic terms, so this a view to be taken seriously. Now, as it happens, I find views such as that expressed by Reuben Hersh, that mathematics is a social construction, to be much closer to being on the right track. The reason is that such a naturalistic approach gives us a much better prospect of understanding the process of doing mathematics. The problem with mathematical Platonism (to my mind, a likely unsolvable problem) is that it has to resort to an equivalent of magic or revelation to account for how the timeless truths about abstract objects such as numbers impress themselves on our brains.
Naturalists, in contrast, should get further in explaining what mathematicians actually do. If mathematicians deal with abstract patterns, well, so they do. This is something material brains can handle without a need for an underlying Platonic Reality. And if many of these patterns are not physically realized, so be it. This is no more problematic than scenarios for future events being represented by material brains, scenarios that may or may not come to pass. Abstraction also seems akin to the way we can recognize multiple realizations of a pattern. Indeed, it seems very plausible that abstraction draws on such mundane capabilities of our brains. And then, we can follow Hersh and try to bring the social context into the picture as well. It’s a complicated task, but it seems doable and partly done.
In other words, we can do metaphysical rehabilitation here as well. Platonism always involves claims about how knowledge is acquired. We can bring such claims down to earth, and have them compete against naturalistic approaches that draw on cognitive science and notions such as social constructions. There should be little doubt that, given our present understanding of how the world works, naturalistic accounts of abstract reasoning are more promising.
Now on to morality. The naturalistic move is similar: we ask how moral knowledge is acquired, and see if we can account for this within the natural world. I think we can. The options I’m partial to incorporate something from error theories, claiming that our normal perception that prescriptive, objective, transcendent moral truths exist and can be intuited is mistaken. They also draw on the cognitive neuroscience of moral perception, social science about negotiating competing interests, evolutionary biology to see what stable interests we have, and so on. Though far from complete, we still can see the outline of a complex, broadly scientific description of our moral ecology. It is superior, I think, to competing metaethics.
All the explanations of our moral lives will not give us any palpable “oughtness.” They will not determine our choices when we face any real moral dilemma. Nonetheless, I don’t know if there is anything more for naturalism to achieve here. Understanding our moral lives in terms of interests and agreements within nature and nothing beyond does not change the fact that we, when personally in a situation where we make choices, have to make the choice. That shift to a personal perspective—you have to be there, in person—is unavoidable, but it is also innocuous.
Indeed, I think that the ability to fruitfully investigate and account for multiple forms of discourse within nature, including natural science itself, is one of the strongest recommendations for an unapologetically scientific naturalism. Naturalistic explanations for our ability to do mathematics, ethics, religion and so on can be contrasted to rehabilitated metaphysical explanations for these abilities, which will usually propose some kind of power of illumination or supernatural intuition. As usual, I think that naturalistic explanations are superior.
Let me put this another way. I envision scientific, nonmetaphysical naturalism as providing us with the best explanation of what we are doing when engaging in various discourses. But this naturalistic understanding does not substitute for these discourses. It does not, in particular, require us to assimilate mathematics, ethics and so forth into a generalized scientific enterprise. It does not, for much the same reason that engineering is not a mere extension of science, while not working with anything supernatural. For one thing, there is no such thing as The Scientific Method. More important, we have multiple aims in life, and we cannot expect all our aims to be served by an enterprise devoted to explaining how the world works.
I really need to figure out how to wrap all this up.