“Two things fill the mind with ever new and increasing admiration and awe, the oftener and more steadily we reflect on them,” wrote Immanuel Kant, “the starry heavens above and the moral law within.” These days, the moral law within is being viewed with increasing awe, if not always admiration. The human moral sense turns out to be an organ of considerable complexity, with quirks that reflect its evolutionary history and its neurobiological foundations. These quirks are bound to have implications for the human predicament. Morality is not just any old topic in psychology but close to our conception of the meaning of life. Moral goodness is what gives each of us the sense that we are worthy human beings. We seek it in our friends and mates, nurture it in our children, advance it in our politics and justify it with our religions. A disrespect for morality is blamed for everyday sins and history’s worst atrocities. To carry this weight, the concept of morality would have to be bigger than any of us and outside all of us. So dissecting moral intuitions is no small matter. If morality is a mere trick of the brain, some may fear, our very grounds for being moral could be eroded. Yet as we shall see, the science of the moral sense can instead be seen as a way to strengthen those grounds, by clarifying what morality is and how it should steer our actions.
