The "is" of science and the "ought" of morality

"So, I come to this field both as a philosopher and as a scientist, and so, my real, core interest is in this relationship between the "is" of moral psychology, the "is" of science, and the "ought" of morality. What I'd like to do is present an alternative metaphor [to the one that Haidt offered], an alternative analogy, to the big picture of moral psychology. " Joshua Greene.