Link back to commentThank you Peter for your response. You raise very important and relevant issues in your objection, I will firstly answer your point on equal moral worth.
Thank you for pointing out your understanding and approach to universal humanism as the focus being on their equal possession on certain rights/moral obligations on the basis of their humanity. I feel a certain clarification is needed by me since I did not mention this point in my article, and that is when I observe moral claims such as 'he is my brother', I am not saying that my brother is 'worth' more than other human beings in the sense of 'matters more in the greater scheme of things', but in the sense of that he matters more 'to me'. So, I do not assume an intrinsic elevated value on the basis of group membership, but a more relativistic value.
This brings me to your objections concerning cultural relativism. I can only agree with all those points, as I too am not a cultural relativist for similar reasons as you laid out. But if we add context to moral assertions based on group membership, we can see quite clearly where they are morally relevant and when they are not. If I were to cover up my brother's involvement in killing spree, merely asserting that he is my brother would not be enough, whereas justifying buying him a Christmas present instead of a stranger in the street, would be enough of a reason. So, I think we can consistently hold value on group membership in some cases but not in others, it need not be a zero-sum game.
Regarding utiltarianism, the impartial observer thought experiment is actually Singer's. He uses it as a defence of expanding our moral considerations on utilitarian grounds. That said, I appreciate his flavour of utilitarianism is only one of many, so yours might be quite different. So I was assuming the IO since it was used on the basis of rejecting group membership on utilitarian grounds.
I'm not however entirely sure that appealing to proximity and practicality saves the utilitarian. Appealing to Singer again, his famous 'child in the pond' thought experiment demonstrates that in today's world, we can save a child's life with pretty much our credit card number and a click of a button. So me buying my son a Christmas present instead of using that money to go to charity, I have basically allowed a child to die in a pond so I don't wreck my new shoes.
Also, there are cases where practicality is separate from the issue. Williams mentions this when he observes that we do nothing to stop other animals from harming one another, Utilitarians will retort the practicality argument that this is too hard to do. Williams replies to this by saying "they are ignoring the more immediate reaction we have to such suggestions, that there is something crazy about the idea!"
I have rushed this reply out so sorry if I missed some points, feel free to reply/object/clarify again,
Thanks again,
Andrew.