We tried to identify the full range of phenomena across cultures that would need to be explained by any adequate theory of human morality. We identified five sets of concerns, each linked to an adaptive challenge and to one or more moral emotions, as the best candidates for the psychological foundations of human morality. The five foundations we identified are harm/care, fairness/reciprocity, in-group/ loyalty, authority/respect, and purity/sanctity.

Haidt J, Joseph C (2007) The moral mind

This seems an interesting theory not much because it tries to answer, but because it provides a model to review our own ethics and compare with other people.

From the same paper:

• Harm / Care — is associated to compassion. It’s meant to protect and care for young, vulnerable, or injured kin. It’s elicited by suffering, distress, or threats to one’s kin.
• Fairness / Reciprocity — is associated to anger, gratitude, and guilt. It’s meant to reap benefits of one-to-one cooperation with non-kin. It’s elicited by cheating, cooperation, deception.
• In-group / Loyalty — is associated to pride, and belonging. It’s meant to reap benefits of group cooperation. It’s elicited by group threats and challenges.
• Authority / Respect — is associated to respect and fear. It’s meant to negotiate hierarchy. It’s elicited by signs of dominance and submission.
• Purity / Sanctity — is associated with disgust. It’s meant to avoid microbes and parasites. It’s elicited by waste products, diseased people, and taboo ideas.

I found this model useful because it provides a way to approximate ethics between people in a more universal way, without getting in the specific language and formulation of the (sub)culture they relate to.

In difficult conversations it can be useful to go back and clarify where there’s agreement on the points above, as it could provide some foundation to find common ground.