We put down rabid dogs. We kill dangerous bulls. We slaughter diseased sheep before they infect the herd. We destroy deformed births. We even drown babies born too weak or badly formed. This isn't cruelty — it's practical reasoning. We separate what's harmful from what's healthy.
The same goes for punishment. Nothing undermines punishment more than anger. Punishment works better when it comes from calm judgment, not rage. That's why Socrates told his slave, "I would hit you if I weren't angry." He waited until he cooled down to discipline the slave. In that moment, he was disciplining himself instead.
Who can claim to control their emotions when even Socrates didn't trust himself with his anger?
We knock mad dogs on the head, we slaughter fierce and savage bulls, and we doom scabby sheep to the knife, lest they should infect our flocks: we destroy monstrous births, and we also drown our children if they are born weakly or unnaturally formed; to separate what is useless from what is sound is an act, not of anger, but of reason. Nothing becomes one who inflicts punishment less than anger, because the punishment has all the more power to work reformation if the sentence be pronounced with deliberate judgment. This is why Socrates said to the slave, “I would strike you, were I not angry.” He put off the correction of the slave to a calmer season; at the moment, he corrected himself. Who can boast that he has his passions, under control, when Socrates did not dare to trust himself to his anger?