What is the best way to understand the true nature of the objects of our conceptions (including ethics, truth, counterfactuals, etc.)? One option, which I think underlies much analytic philosophy, is to reify the conceived object - ascribing to it an independent existence - and then to inquire after the actual properties of this object. This treats the object ahistorically and on its own terms, focusing on what it is, not where it came from or how we learnt of it.
The latter alternative is suggestive of a naturalized philosophical methodology, informed especially by cognitive science. The focus is on the mental conception, rather than the thing conceived. (Compare the distinction between the mental state of belief, and the content or 'thing believed'.) Down this path, we might ask how the conceptions arise and what role they play in our broader cognition. Only later - if at all - would we step outside ourselves to draw metaphysical conclusions about external reality.
An even more extreme approach to 'naturalizing philosophy' would look to the evolutionary origins of our conceptual framework. (We now appear to be two steps removed from the original object of inquiry.) That is to ground humanistic philosophy upon evolutionary psychology.
So: which of these three paths is best? Or might they yield complementary insights?
Despite the enthusiasm of many evolutionary theorists, I'm not convinced that a scientific understanding of our origins is the be all and end all. In some cases, it rather seems to obstruct a fuller understanding of our experiences. Steven Pinker once described music as "auditory cheesecake" - a combination of stimuli which just happens to press all the right buttons to activate our neural pleasure centres. But this neglects so much of importance about our aesthetic experiences. Listening to Beethoven's Pastoral symphony, there is an undeniable beauty in it which simply cannot be captured by any account of our aesthetic experience that ignores the actual music! Or so it seems to me, at least.
There are interesting philosophical questions about the nature of beauty, and whether it is properly a quality of the object itself, or how we experience it, or some combination of the two; but these sorts of questions don't seem open to a purely scientific account. (Hence their being philosophical, rather than scientific, questions!)
Evolutionary (meta-)ethics is another example. An hypothesis about how moral behaviour evolved just doesn't seem to tell us that much about the real nature of morality itself. Perhaps it recommends a sort of skeptical anti-realism about ethics (and normativity more generally). But it seems to be leaving out something important, so I'm doubtful that such scientism can really provide the sort of deeper understanding that we're looking for here.
This might relate to my old post on the two conceptions of objectivity. Scientific objectivity proceeds by cutting things out of the picture. But if we want a fuller understanding (whatever that involves), we might do better to instead pursue the 'Hegelian' ideal of expanding our perspective. This would be undermined by the scientistic assumptions underlying the extreme forms of 'naturalized philosophy'.
What about the more mild approach? There's a lot of work being done now in the field of "moral psychology", for example. I don't really know anything about it though, so I've no idea how helpful or illuminating that may be to ethics. Two underexplored areas that I'd like to learn more about would be mathematical and modal cognition. How does the mind apprehend and manipulate mathematical objects? If we knew all the internal/psychological facts about our mathematical cognition, would that provide a full explanation of mathematical truths? Or would we still require something further, e.g. a platonic realm of mathematical objects, and facts about the same?
And what of modal cognition? How do people think about counterfactuals, or judge what is or isn't possible? And how does this cognitive processing relate to external facts? Could our beliefs have abstract truthmakers (e.g. numbers, or possible worlds) that are causally inaccessible to us? I'm not sure how that would work. But then what determines whether our beliefs on those topics are true? My hope here is that psychological research might provide us with the resources to find constructed truthmakers - a way to build truthmakers out of idealized mental processes, and thus avoid extravagant (Platonic) ontological commitments. This sort of constructivism seems very much more in line with the 'Hegelian' ideals pointed to above. So perhaps 'naturalized' philosophical methodologies aren't all bad?