Revenge might be part of our biology that encourages pair-bonding and defense of the groups we belong to. Unfortunately, we also can use our rationality to justify cruelty and violence which goes beyond what is necessary for defense.
One can become "defenseless" by taking some distance from what one feels the need to defend to ask if the defense is really in everyone's best interest. Some of the things we defend that are not worth defending as strongly as we might feel the need are our opinions or our "honor", whatever that is.



