"He likens the mind’s subterranean moral machinery to an elephant, and conscious moral reasoning to a small rider on the elephant’s back."

How morality may have evolved:

In... "The Happiness Hypothesis," Jonathan Haidt, a moral psychologist at the University of Virginia, has been constructing a broad evolutionary view of morality.... driven by two separate mental systems, one ancient and one modern, though the mind is scarcely aware of the difference. The ancient system, which he calls moral intuition, is based on the emotion-laden moral behaviors that evolved before the development of language. The modern system — he calls it moral judgment — came after language, when people became able to articulate why something was right or wrong.

The emotional responses of moral intuition occur instantaneously — they are primitive gut reactions that evolved to generate split-second decisions and enhance survival in a dangerous world. Moral judgment, on the other hand, comes later, as the conscious mind develops a plausible rationalization for the decision already arrived at through moral intuition.

Read the whole thing. And take the tests. I did. The tests compare your answers to the answers of political conservatives and liberals, and, for me, supported my belief that I am in the middle. (I'm not sure whether my test results were classified as conservative or liberal. You're asked several questions in the beginning, about social issues, economics, and national security. Since I go left, middle, and right, respectively, on those questions, I don't know where my answers counted.)