Morality evolved! One can quibble about the precise meaning of those two words, but the sentence remains true regardless. Absent genetically programmed and heritable physical characteristics of the human brain, morality as commonly understood would not exist. It follows that good and evil have no existence other than as subjective impressions in the minds of individuals.
So much is obvious. It will become increasingly obvious as long as researchers remain free to study that incredibly complex biological computer, the brain, and the genetic processes that bring it into existence. So much is, however, also inconvenient. It is our nature to derive a great deal of pleasure from self-righteousness and virtuous indignation. However, if good and evil do not exist as independent objects, the rational bases for self-righteousness and virtuous indignation, or, as Jonathan Haidt put it, the rational tail that wags the emotional dog, disappear. They remain interesting and worthy of study as emotional phenomena. However, the notion that they actually have some genuine rational justification becomes absurd.
Similarly, if there are no good and evil objects, the bases for the claims of hosts of philosophers, theologians, and assorted experts on morality of every stripe that they understand those objects better than the rest of us evaporate as well. As a result, as has so often happened with such inconvenient truths in the past, this one faces and will continue to face bitter opposition from those who, for the reasons alluded to above, prefer an alternate version of reality. Like the Blank Slaters of old who denied human nature because it relegated all their fine utopias to the scrap heap, they can be relied on to resist and obfuscate our efforts to gain understanding of the physical, emotional and genetic bases of morality. They realize perfectly well that such understanding renders them superfluous. Recently, their efforts to stem the tide of increasing knowledge have met with a distinct lack of success, even in academia. One must hope they will remain similarly ineffectual in the future, or at least one must hope so to the extent that one believes that an accurate understanding of ourselves will have some bearing on our future survival.
That belief has not always found ready acceptance, even among very intelligent people. For example, a great number of thinkers who doubted the truths of established religion themselves have objected to passing the word on to the “rabble,” fearing that, lacking a reason to be “good,” they would certainly embrace “evil.” Similarly, in our own day, many shrink from rejecting a transcendent Good-in-itself because they fear it will promote amorality and moral relativism. In fact, accepting the truth about morality will not result in amorality or moral relativism because it is not our nature to be amoral or morally relativistic. We are no more likely to change our moral nature than we are to sprout fins and take to the water, or return to walking on all fours, in response to learning the truth about what that moral nature really is, and how it came into being.
That is not to imply that such self-understanding will be useless. For example, it may occur to us to shape a morality that is simple, in harmony with our nature, and that promotes our happiness and discourages us from harming each other as effectively as possible. It may also occur to us to limit morality to spheres in which it can reasonably be expected to promote useful ends. Given the fact that morality is fundamentally an emotional rather than a rational phenomenon, it is unlikely those spheres to which our frail reason might better be applied, such as national politics, international relations, and other aspects of our current reality that didn’t exist when morality evolved, will be included. This remains true even though attempts to apply reason to such spheres without taking the moral nature, not to mention the other behavioral characteristics of our species into account are bound to fail. For example, the creation of laws that injure the average individual’s sense of justice will likely be useless, regardless of how reasonable they might seem to be on other grounds.
Having accepted the origins of morality, let us not shrink from accepting its reality as well. In particular, we should not pretend that it is invariably our nature to be “nice,” and that all “non-niceness” derives exclusively from culture and environment. Just as it is our nature to belong to and seek acceptance by our ingroup, it is also our nature to hate and despise outgroups. It is not possible to suppress or stifle that aspect of our nature. We will always seek and find an outgroup. Consider the behavior of the very liberals and progressives who occasionally suggest chimerical schemes such as expanding our ingroup to include all mankind. Nothing could exceed the spite and fury of their denunciations of those who disagree with them, such as gun rights advocates, Christian fundamentalists, opponents of gay marriage, etc. The outgroup have ye always with you. Our goal should be to stop ignoring this truth, in spite of the fact that all human history is a testament to it, and in spite of the further fact that it is such an obvious explanation for so much about us that otherwise seems incomprehensible, and seek ways of dealing with it so as to minimize the mayhem it has so frequently caused in the past.