Humanity is defined as:
human race: the human race considered as a whole
qualities of human being: the qualities or characteristics considered as a whole to be characteristic of human beings
kindness: kindness or compassion for others
This would seem to indicate that in order for war or aggression to take place that an intrinsic part of one’s humanity would have to be abandoned. How can one human inject a bullet into the head of another and still feel kindness or compassion towards that person. I suppose if the circumstances were appropriate, such as a mercy killing to end suffering, it might be described by hardened hearts as compassion. In some cases I suppose it could be said that the termination of one individual is a kindness to all others. Sometimes to preserve the greater number, the death of one or even a few, can be logically reasoned as necessary. What then of the humanity of those whose fingers are poised on the trigger? Do they pull the trigger with zest or regret? Do they act with apathy or empathy? Do they act with determination or hesitation? Those who can kill without regret or backlash of conscience seem lacking in some degree their humanity. Is that an apathetic machine like finger on the assassins trigger? Even where survival is concerned, what part of humanities psyche motivates the trigger finger?