Reason

Humans have one faculty above all other animals in the kingdom - reason. Socrates attributes a great deal to our ability to reason and be able to avoid fits of anger. He also recognizes that anger only arises in cases where reason can exist. By that logic, it seems humans are the only ones able to both be capable of anger, along with defeating it by the same tool. It’s only by reason that we should inflict punishment, and the only way to inflict punishment justly is to correct potential future actions of society. Punishment is never just when it is plagued with emotional rage in the heat of the moment.