Haidt’s work has shown that the liberal morality is built mostly on the foundation of care. Humans are mammals, and as such we spend a great deal of our lives rearing and caring for our young. We have an innate predisposition to care for others and to prevent one another from coming to harm. To a lesser extent, but still important to liberal morality, is the foundation of fairness/cheating. It is the idea, basically, of reciprocal altruism, and it is on this foundation, along with the other liberal foundations, which are built liberal notions of fairness. A third component of the liberal morality, new to Haidt’s research, is that of liberty/oppression. Humans are hierarchical by nature, but we tend to “gang up” and defend ourselves when we think we are being bullied by those above us on the hierarchy.
From the liberal moral foundations follows an understanding of morality as “preventing harmful or unfair consequences to other people.
In Haidt’s article “Morality,” (1) he says
“This way of thinking (morality = not harming or cheating others) has become a kind of academic common sense, an assumption shared widely by educated secular people. For example, in Letter to a Christian Nation, Sam Harris (2006,) gives us this definition of morality: “Questions of morality are questions about happiness and suffering . . . To the degree that our actions can affect the experience of other creatures positively or negatively, questions of morality apply.”
(1) Haidt, J., & Kesebir, S. (2010). Morality. In S. Fiske, & D. Gilbert (Eds.) Handbook of Social Psychology, 5th Edition.. Available on the Publications page of Haidt’s web site.