If a man has been taught that fighting is for people who can’t use their heads to solve problems, who is to say he’s wrong? This shall be "y".
Culture x wages war against culture y. A man from culture x is captured as a prisoner, but they do not beat him, and gradually, he learns to love them and their unwillingness to cause pain on others. He gives up fighting forever. Back at base in culture x, he is deemed a blood traitor and is eventually assassinated for giving up his glory, honour and dignity.
Which culture is right? Is there really an answer to that? Where are the limits? If it becomes acceptable in culture "z" to rip someone’s teeth out because you want to, is that wrong? Well the good people of culture z don’t think it is. x and y might, but to z, that’s life for you. Where are the lines? How do we know what is really considered "right" in terms of moral and culture?
I don’t know.