We don’t know what other people see

Following my previous post I realised that it implies we all see the world differently and unless we are very open to talk with other people we cannot know how they see it except by analysing their behaviour,perhaps
So if people kill others who seem harmless to us clearly their world view is different.
It is possible and it has happened that some political leaders managed to persuade their countrymen and women that some other human beings were not really human and so could be killed.
I believe the Nazis did this vis- a-vis the Jews describing them as rats or cockroaches.And denying lavatories to people in Concentration Camps so  they soiled themselves made it  easier for the guards to kill them as their dirtiness reduced their status and made them seem less human.It’s not logical because anyone would soil themselves in such conditions but when has reason ever been used much in politics or ordinary life?
That is a rhetorical question.