For several years now, students in my Introduction to Ethics class have been unwitting participants in a moral experiment. After some six years the results are in. But I do not know how to interpret the results.
We think our beliefs extend back to the facts. This is what makes them rational. But if contemporary social psychology has revealed anything, it's that very many of our beliefs (let alone our desires) have very different origins. And this makes a difference in what you ought to believe.