I am arguing that the “moral emotions” you list (empathy, guilt, righteous indignation, etc.) are not really in-built at all, but products of the society in question, though they do rely on certain fundamental instincts. (Of those you list, perhaps empathy is the only one that is really fundamental.) This view implies that cultural moral systems do not rely on the arbitrariness of evolution, but on the slightly less arbitrary factor of intelligence, which is the main shaper, other than our fundamental instincts, of culture.

I agree that there is no “should” in science, and that one cannot go directly from an is to an ought. I admitted as much in the conclusion of the essay. But one can have rather too strong an allergic reaction to good advice based on observations of the world. It is not arrogant, nor is it misplaced, for an economist to tell a president that he should not print any more money lest the country undergo heavy inflation and ultimately collapse. The advice itself is not objective truth, but the arguments that show how A leads to Z are.

To start, your first premise is false.

Our deepest instincts are rooted in the survival of our personal DNA and the DNA we share with close relatives. Whether those instincts increase the chances of the survival of our species is irrelevant. These survival instincts include greed, desire to dominate others by violence, and other nasty instincts that have nothing to do with morality.

In the field of evolutionary morality, it is uncontroversial that our DNA based biology that produces our moral emotions like empathy, guilt, and righteous indignation exists as only ONE set of strategies to increase our inclusive reproductive fitness (survival of our DNA). Further, these emotions accomplish this feat by motivating behaviors that increase the reproductive fitness benefits of cooperation in groups.

It is also appears that virtually all past and present cultural moral standards (that advocate unselfish behaviors) are heuristics for increasing the benefits of cooperation in groups. However, the benefits of cooperation advocated by cultural moral standards can include emotional and material goods rewards, not just reproductive fitness benefits.

There is no ‘should’ in science. Science only tells us what ‘is’ and science appears to tell us that cultural moral standards and biologically based moral emotions are cultural and biological heuristics for exploiting the benefits of cooperation in groups. If people decide they ‘should’ use that information for their benefit, that is up to them.

I suggest the biggest help you will ever get in understand morality is to understand winning game theory strategies in environments where synergistic benefits of cooperation are available. These environments necessarily include virtually all environments inhabited by intelligent beings, human or otherwise. Intelligence is not the enemy of morality, it is what makes morality possible.