In-group

There is a natural tendency for humans to define themselves in terms of in-groups and outsiders.

This makes sense from an evolutionary perspective, but in a globally connected society it can lead to chaos. There are so many overlapping in-groups that cross all national and cultural borders that attempting to define them in any way creates tons of exceptions.

The only morally defensible in-group is all humans, and outside the realm of survival that should be expanded to also include all living things. Any hierarchical subdivision is inherently unjust.