I oversimplified my comment . See my comment below as to why Westbrook can ' t get it done on his own . <| sep |> I think we are using the phrase all or nothing in two different ways . I was using it to describe the author ' s approach of attempting to find a single difference between animals and humans which could justify our killing and eating them . My assertion is that there is not a single justification , but rather a twoelement test which could provide a criteria for when it is morally permissible to kill and eat an animal . Obviously , the end result must necessarily be an all or nothing scenario . You cannot partially kill a cow . Unless , of course , it ' s Schrdinger ' s Cow , in which case it ' s both alive and dead at the same time .