Funnily enough, I just wrote an essay on the related meta-ethics topic, Singer’s Whiggish ‘expanding circle’ thesis: http://www.gwern.net/Notes#the-narrowing-circle
Funnily enough, I just wrote an essay on the related meta-ethics topic, Singer’s Whiggish ‘expanding circle’ thesis: http://www.gwern.net/Notes#the-narrowing-circle