It is clear that this is a very fundamental idea underlying a lot of halacha, hashkofa and psychology. "Judge others favorably", Don't judge others until you are in their place. Be kind to the stranger. Love others as yourself, Don't torment others, woman is the other, Satan is the other, Amalek is the other, Why was Acher named Acher?, cherem and kares make a person into the other, t etc etc
WHAT IS THE CONCEPT OF THE OTHER? Is it simply whatever lies outside of yourself?' In other words is it "not you".
I have come across one book [which is out of print] that deals with this האחר -בין אדם לעצמו ולזולתו עורים חיים דויטש מנחם בן ששון