Most Greeks, in those days, identified with their individual city-state or with being Greek as a group. Now the individual could be part of two communities, the one in which they were born and the community of mankind in general.
Pluralism recognizes and promotes diversity within a nation or state. This permits the peaceful acceptance of different lifestyles, ideas, and beliefs.
The relation between the cosmopolitan ethics and pluralism is that that both go beyond local prejudices and cultural patterns to embrace the fact that the world is large and so many people can’t all have the same way of looking at things.
Both cosmopolitan ethics and pluralism foster the idea that not only can we live in peace with one another, through acceptance and tolerance, but also benefit by contributing knowledge and understanding to each other’s lives.