In Kant the other is only considered in terms of her autonomy, as sharing something with me. Kant's ethics is perhaps the origin of the idea of an alter-ego - the other me who is the subject of his ethics. Further, perhaps it is the very starting point of a general idea of ego, an ego that can be generalized like in the categorical imperative: don't do to other what I don't want done to me – and not don't do to others what they don't want to be done to them. Hence, it is moral to tell the truth to the murderer and enable him to kill because enabling someone to so something is an empirical consideration alien to moral issues. In other words, it is up to the murderer to be a moral agent. I should threat all the others in the same manner – the other is universal, they are universal mes. They are never other – I don't deal with the murderer as an other, not even as a murderer for that matter, but only as an autonomous moral agent like me.