There ' s one guy who says I forgot to save , but that ' s alright because I ' m going to win anyway ! when you start a battle with him <| sep |> But the pig might say . Except no pig can say , both because the pig can ' t speak and , more importantly , because the pig can ' t reason . The ability to think , understand , and form judgments by a process of logic is the key difference between us and the animals we kill for food . The ability of the species to reason makes the species immoral to eat . His severely retarded brother , even if he lacked the ability to reason , is still a member of a species which can reason , so killing his brother is different than killing a pig . Likewise , we as a species clearly reason , so it is immoral for the alien to kill us for food , but not for us to kill pigs for food .