An eye for an eye. That seems equal, but is it really? I'm sure that if I cut off Phelp's arm, he would still have lost more than I did if my own arm is cut off as punishment, haha. How then can we measure if a response to something is proportionate? Example, if you steal an item, your payment would most likely be fines bigger than the value of what you stole or even imprisonment. What if X country bombs a school and kills 20 people in Y country? Do you think that simply bombing back a school (20 casualties too) in X country would be perceived by people as appropriate and just response? Is being "fair" something we really seek or is our idea of equitable retaliation more based on "you've done bad things to me, therefore I would do bad things to you" (without thought to the gravity)?