Revenge is bad

Rihatsu: Revenge is bad.
Interlocutor: Why? Other than because it's acting on emotion rather than reason.
Rihatsu: Because when one seeks revenge, one is putting one's creativity into harming someone, and thus forcing them to put theirs into fending off that harm. So one ends up creating nothing, and using two people's creativity. You could both have spent that effort producing something valuable.
Interlocutor: If you have a policy of revenge, though, it should put people off harming you in future, which would mean as long as people know you have the policy and avoid harming you, you won't actually need to get revenge.
Rihatsu: That's bad firstly because it's coercion—so if someone does something they think is good but they're mistaken, or if you have bad ideas, then you will end up seeking revenge mistakenly. For example, if someone hated criticism, and sought revenge every time they were criticized. It is as bad as enacting any coercive force on people. Secondly, because if you had that policy and then met someone new, it might take a long time for them to realize that that was your policy, so a lot of hurting would occur before they submitted to your coercive attitude. Note that "submitting" ought not to be the aim of interaction for any civilized group of people.
Interlocutor: You could make it clear that that's your policy and only do it to people who actually do something harmful to you (so that even if it is a mistake, they still had a chance to work out how you'd react). For a big example of the former, we have the state, which punishes people who break it's laws to stop them harming it (and lots of other stuff).
Rihatsu: We are not discussing populations here, but interpersonal relations. One can use reason much more creatively, as the choice here is not between Rule of Man or Rule of Law. Additionally, you're presuming there to understand what "actually harmful" means; but that is not infallibly obvious, and two people may have different ideas of what constitutes harm depending on how mistaken they are. So I believe that proposition was meaningless. Surely it would be better to have a policy amongst your friends of not hurting each other, so if someone is hurt then it was almost certainly accidental and therefore easy to solve.
Interlocutor: That might not discourage strangers, who think they'll be unlikely to gain anything from participating in a not-hurting system, or very irrational people.
Rihatsu: Rational strangers would recognize the value of not hurting people. Why would you want to be friends with irrational people? Unless you had a specific reason that mitigated the irrationality, in which case... it would be worth it anyway, or else it wouldn't quite be worth it, so you wouldn't know them. Two wrongs don't make a right; one right makes a right.
Interlocutor: You might be forced into associating with them, like if they work or study at the same place as you or if you run a state and need to account for all your citizens.
Rihatsu: I don't see why it wouldn't be better to find ways of not being affected oneself by their irrationality, rather than finding ways of lowering yourself to their level.
Interlocutor: Their irrationality might be very hard to avoid, like if, say, a co-worker makes the whole workplace less efficient by being distracting and bad at the job.
Rihatsu: Then why would more people being irrational make things more efficient?
Interlocutor: if you do something for revenge (like not car-pool for them) they'd have incentive to be more productive.
Rihatsu: That never happens. People do not like to be humiliated, and would just seek more counter revenge. And besides, if the problem is that they are irrational, and as a result unproductive and inefficient, then that won't change properly until they are persuaded. And force does not contain knowledge.
Interlocutor: I see. I agree.
Rihatsu: Not to mention, hurting people is unpleasant. I dislike situations in which people get hurt. I wouldn't want to create one, or prolong one.