We now have a better biological and psychological understanding of our moral thinking. The idea that we should do what maximizes happiness sounds very reasonable, but it often conflicts with our gut reactions. Philosophers have spent the last century or so finding examples where our intuition runs counter to this idea and have taken these as signals that something is wrong with this philosophy. But when you look at the psychology behind those examples, they become less compelling. An alternative is that our gut reactions are not always reliable.