Moral philosophy explores how people ought to act. The point of that word ‘ought’ is to acknowledge that in reality people aren’t perfect, that they could and should do better. So, since moral philosophers are mainly interested in what ought to be done, is there much reason for them to pay attention to psychological descriptions of what people actually do? I think there is, and my research explains why.
the causes of moral judgment
Philosophers often treat judgments (or ‘intuitions’) about particular cases as pieces of evidence for or against general moral principles. The best moral principles are those that draw together the greatest number of important intuitions. But where do our moral intuitions come from? What causes them? Psychology can help to answer these questions. And the answers matter. It is important that our moral intuitions express values we can hope to share with other people, rather than arbitrary fluctuations of our own personal psychologies. (Here is a paper on this point.)
the psychology of moral agency
It makes sense to say that Dr. So-and-so ought to have done such-and-such. But it doesn’t really make sense to say that a rock, or even a squirrel, ought to do such-and-such. We reserve moral judgment for the actions of agents – that is, for entities that have some power to reflect on the reasons for their actions, and to make this reflection matter to what they end up doing. By default, we tend to assume that the actions of healthy adult humans are like this — but psychology seems to be showing otherwise. Many of our actions seem to be automatic, in that they happen in ways we are not consciously aware of choosing. Sometimes, like when we acquire and sustain good habits, automatic behavior is valuable. But some of the things we do automatically turn out to be completely disconnected from our reflective awareness. Are we really moral agents when we act in these ways? This is a question for moral philosophy, but it cannot be answered without knowing the psychological details.