Pietraszewski should be complimented for trying to obtain order and system in the chaotic concept of group dynamics.

I think the model has a weakness in the scaling up of the triadic primitives to interactions between groups. The difference between intragroup conflict and intergroup conflict is not just a matter of scale. The whole social organization is often radically different between groups dominated by intragroup conflict and groups dominated by intergroup conflict (Fog, Reference Fog2017).

The article mentions that subgroups opposing each other in a civil war may unite against an external common enemy. But the model does not adequately cover the complexity that can be observed in groups facing external enemies. Research on cultural evolution and evolutionary psychology shows that violent conflicts between human groups can lead to an arms race that drives a development toward increasing complexity. The group that is best at overcoming the collective action problem and motivate its members to risk their lives in a fight for their group is likely to win territory from a less organized enemy group. This requires a strong hierarchy, discipline, and a strong leader who can punish free riders, reward brave warriors, and organize the fighting. History shows that this mechanism can drive a cultural evolution toward ever-growing political units and increasing complexity. The strongest groups need an increasing division of labor with leaders, bureaucrats, police, judges, and of course soldiers, weapon producers, and food producers. They also tend to develop a political organization, culture, religion, and ideology that supports and motivates the collective fighting.

Groups with only internal conflicts and no external enemies tend to develop in a very different direction. Members of such groups will not tolerate a strong hierarchy with a kleptocratic tyrant at the top. Instead, we can observe that groups in peaceful surroundings tend to develop in the direction of egalitarian, tolerant, and democratic cultures (Fog, Reference Fog2017).

If we want to build a theoretical model that describes groups in external conflict then we need to include the complexities of the collective action problem and the mechanisms necessary for making people sacrifice themselves for their group. The theory presented by Pietraszewski can be useful for game-theoretical models of groups with only intragroup conflicts, but it cannot adequately capture the drive toward increasing complexity that we have observed in groups dominated by intergroup conflicts.