My friend and I were discussing the nature of justice and we couldn't define it in a way that differentiates it from revenge. Both involve the idea of causing pain/suffering to the perpetrator of a crime since he/she has caused a certain amount of pain/suffering to a person or society. Is the only difference that justice is supposedly 'objective' in the sense that non-involved persons determine the amount of suffering the perpetrator should receive as opposed to the 'subjective' nature of revenge when the victim decides?
This led us to wonder what is the opposite of justice/revenge and we thought it might be mercy, when you do not inflict suffering on the perpetrator. My friend pointed out that each Muslim prayer begins with "In the name of Allah, the most just and most merciful". Is it possible to be both just and merciful at the same time? Isn't there a contradiction there?