The moral sense, then, may be rooted in the design of the normal human brain.

The most effective way to seem generous and fair, under harsh scrutiny, is to be generous and fair.

The qualitative difference between red and green, the tastiness of fruit and foulness of carrion, the scariness of heights and prettiness of flowers are design features of our common nervous system, and if our species had evolved in a different ecosystem or if we were missing a few genes, our reactions could go the other way. Now, if the distinction between right and wrong is also a product of brain wiring, why should we believe it is any more real than the distinction between red and green? And if it is just a collective hallucination, how could we argue that evils like genocide and slavery are wrong for everyone, rather than just distasteful to us?

This throws us back to wondering where those reasons could come from, if they are more than just figments of our brains. They certainly aren’t in the physical world like wavelength or mass. The only other option is that moral truths exist in some abstract Platonic realm, there for us to discover, perhaps in the same way that mathematical truths (according to most mathematicians) are there for us to discover.

Perhaps we are born with a rudimentary moral sense, and as soon as we build on it with moral reasoning, the nature of moral reality forces us to some conclusions but not others.

Moral realism, as this idea is called, is too rich for many philosophers’ blood. Yet a diluted version of the idea — if not a list of cosmically inscribed Thou-Shalts, then at least a few If-Thens — is not crazy. Two features of reality point any rational, self-preserving social agent in a moral direction. And they could provide a benchmark for determining when the judgments of our moral sense are aligned with morality itself.

The other external support for morality is a feature of rationality itself: that it cannot depend on the egocentric vantage point of the reasoner. If I appeal to you to do anything that affects me — to get off my foot, or tell me the time or not run me over with your car — then I can’t do it in a way that privileges my interests over yours (say, retaining my right to run you over with my car) if I want you to take me seriously. Not coincidentally, the core of this idea — the interchangeability of perspectives — keeps reappearing in history’s best-thought-through moral philosophies, including the Golden Rule (itself discovered many times); Spinoza’s Viewpoint of Eternity; the Social Contract of Hobbes, Rousseau and Locke; Kant’s Categorical Imperative; and Rawls’s Veil of Ignorance. Morality, then, is still something larger than our inherited moral sense, and the new science of the moral sense does not make moral reasoning and conviction obsolete. At the same time, its implications for our moral universe are profound.

The science of the moral sense also alerts us to ways in which our psychological makeup can get in the way of our arriving at the most defensible moral conclusions. The moral sense, we are learning, is as vulnerable to illusions as the other senses. It is apt to confuse morality per se with purity, status and conformity.

In the worst cases, the thoughtlessness of our brute intuitions can be celebrated as a virtue. In his influential essay “The Wisdom of Repugnance,” Leon Kass, former chair of the President’s Council on Bioethics, argued that we should disregard reason when it comes to cloning and other biomedical technologies and go with our gut: “We are repelled by the prospect of cloning human beings . . . because we intuit and feel, immediately and without argument, the violation of things that we rightfully hold dear. . . . In this age in which everything is held to be permissible so long as it is freely done . . . repugnance may be the only voice left that speaks up to defend the central core of our humanity. Shallow are the souls that have forgotten how to shudder.”There are, of course, good reasons to regulate human cloning, but the shudder test is not one of them.

The threat of human-induced climate change has become the occasion for a moralistic revival meeting. In many discussions, the cause of climate change is overindulgence (too many S.U.V.’s) and defilement (sullying the atmosphere), and the solution is temperance (conservation) and expiation (buying carbon offset coupons). Yet the experts agree that these numbers don’t add up: even if every last American became conscientious about his or her carbon emissions, the effects on climate change would be trifling, if for no other reason than that two billion Indians and Chinese are unlikely to copy our born-again abstemiousness. Though voluntary conservation may be one wedge in an effective carbon-reduction pie, the other wedges will have to be morally boring, like a carbon tax and new energy technologies, or even taboo, like nuclear power and deliberate manipulation of the ocean and atmosphere. Our habit of moralizing problems, merging them with intuitions of purity and contamination, and resting content when we feel the right feelings, can get in the way of doing the right thing.

Far from debunking morality, then, the science of the moral sense can advance it, by allowing us to see through the illusions that evolution and culture have saddled us with and to focus on goals we can share and defend. As Anton Chekhov wrote, “Man will become better when you show him what he is like.”

you wrote:
"So the morality of the situation, in the actual minds of humans, is decided up front based on an instinct and then back-rationalized."

you wrote:
Because this is how people actually judge things, and how they decide what to do and how to act.

Far from debunking morality, then, the science of the moral sense can advance it, by allowing us to see through the illusions that evolution and culture have saddled us with and to focus on goals we can share and defend.

gforce677 wrote:
I think the author and you shoud read nietzsche's On Truth and Lies in a Nonmoral sense. (and N in general)

This cannot be done, however, by one side gaining the victory.