Let's assume that humans have an in-built instinct to care for other humans, and that this helped us to survive in a harsh and dangerous environment, hence it was selected for. Small bands of homo sapiens among whom this instinct was relatively stronger, tended to survive and reproduce compared to others among whom it was weaker. Let's further assume that this instinct is the motivation for behaviour we would describe as moral, such as helping an old lady cross the street or diving into a river to rescue a drowning person.
If this were true, then it would mean that morality is ontologically prior to society and culture in that it has a genetic substrate, but like most human behaviours also requires a cultural context in which it is taught and fostered.
This would mean that in broad terms we could expect human moral behaviour to have a lot of commonality across societies in time and space, but differences in specifics, just as human languages have similar structures such as verbs and nouns, subjects and predicates, while having a great deal of culturally specific variety in the ways those linguistic structures are implemented.
It would also seem to mean that social norms can be evaluated somewhat objectively between cultures, if we consider how well they foster and incentivise this instinct. Generally, cultures can do various things with human tendencies: they can incentivise or discourage them, they can also seek to constrain them to specific contexts or channel them towards social goals, as happens with sex, or they can disparage and punish them, as self-preserving behaviour usually is if it happens at the expense of group survival in an existential crisis.
Society A might have a sense that all humans deserve to flourish, even in other societies, so it might highly value traits such as compassion and empathy.
Society B might believe that different cultures or societies exist in a state of competition, a kind of Social Darwinisnm. On that basis they might regard compassion with suspicion: good when it motivates you to rescue a comrade on the battlefield but a dangerous weakness when it makes you feel sorry for foreigners and try to help them.
It's natural to expect that Society A would cultivate the human moral instinct in an unqualified fashion, but Society B would seek to constrain and limit it while still turning it towards social goals.
If we consider that the moral instinct is part of what makes us human, then societies which expend more effort in fostering this instinct, and develop it more effectively in more sophisticated and wide-reaching ways, are objectively doing a better job of raising humans, all else being equal, and we could say this about Society A in comparison to Society B.
This could provide a somewhat objective yardstick for evaluating our own social progress and comparing social norms across different contexts.
Is this a position that could be made philosophically rigorous against cultural relativism?
