If your morality is just about social cohesion then you can justify actions that only hurt those outside your social group, such as imperialism and slavery.
Also, the OP was semi-joking (but I do find the idea interesting)
Also, the OP was semi-joking (but I do find the idea interesting)
My point was that a society stratified between free people and slaves, or that invades other countries for resources, can be internally peaceful. Does that make it just?
As in, the social group would be maintained perfectly well. Just in an unjust form.