"Imagine that one day you just suddenly could no longer see your husband, or some of your friends, or half of your co-workers. Well that's what happens in the story Sword of Polarity by Michael Klein. In the story entire groups of people literally just disappear from your visual field. The narrator is offered a pair of glasses to fix this problem but ends up refusing them, saying that it's just easier to go about life as they have been, to continue to see the people that they can see and be blind to those that they're blind to. So what would philosophers say about this? Well I think really this is an issue of communitarianism versus cosmopolitanism at its heart. Communitarianism argues that our identity and our moral vocabulary and our ethics are deeply tied to our community background. In other words people are really thoroughly embedded in their own social context. It also makes you think politically of something like nationalism, where basically your priority..."