After Virtue by Alistair McIntyre

After Virtue by Alistair McIntyre is apparently the biggest deal in moral philosophy in like the last 100 years or something. It's about this idea of emotivism, where everything ultimately amounts to "I think this is right because I feel like it is right" And his view is that modern ethical discourse is chaotic because there is no longer a strong community consensus on the nature of the proper ends of human existence. If morality is a function of the social conventions of the community and yet the community lacks consensus on those social conventions, or those social conventions are hotly contested, ethical chaos is the result.