Peter Turchin explains why national honour trumps rationality — because it works:
Imagine a livestock herder – a traditional Kazakh nomad or an American cattleman on the Western frontier – who lives in a stateless, anarchic society. His wealth is movable and therefore vulnerable to theft. Since there are no police and no courts, he must rely on his own efforts to protect himself, just as states must rely on themselves to ensure continued survival. In such a situation, one strategy is to maintain a reputation for extreme toughness: ‘If you mess with me, you’ll regret it.’ Potential rustlers are deterred because they know that the owner will go all-out to punish them for any transgression.
Now, on a realist view such as Mearsheimer’s, such retribution would seem irrational. It yields no immediate gain and entails significant costs. If one does it oneself, there is the risk of injury or death. If one outsources the work, a bounty must be paid. But in spite of these liabilities, the punishment strategy turns out to be the one that wins in the long run. Herdsmen who do not cultivate a tough reputation become ‘men without honour’. Eventually they lose all their herds and become extinct (indeed, that possibility is what makes this genuinely an evolutionary process, although the relevant adaptation is probably more cultural than genetic). ‘Honour’ means that your commitment to punish a thief is credible. You cannot be dissuaded by danger and you cannot be bought off. If you succumb to either temptation, you lose your credibility, and with it, the capacity to deter robbers.
The problem is that rustlers are also under pressure to cultivate tough reputations: they have to intimidate the herders and deter punishment. So we end up in a coevolutionary arms race in which everybody becomes increasingly tough. The end result is a spiral of violence in which all parties run a high risk of extermination. An apparently sensible strategy leads, in short order, to suicidal madness. This is hard to understand within the rationalist framework of offensive realism. From an evolutionary point of view, on the other hand, it seems inevitable.