Every civilization has historically applied different rules to insiders versus outsiders

Evidence

Third, identity at any level—personal, tribal, racial, civilizational—can only be defined in relation to an “other,” a different person, tribe, race, or civilization. Historically relations between states or other entities of the same civilization have differed from relations between states or entities of different civilizations. Separate codes governed behavior toward those who are “like us” and the “barbarians” who are not. The rules of the nations of Christendom for dealing with each other were different from those for dealing with the Turks and other “heathens.” Muslims acted differently toward those of Dar al-Islam and those of Dar al-harb. The Chinese treated Chinese foreigners and non-Chinese foreigners in separate ways. The civilizational “us” and the extracivilizational “them” is a constant in human history. — Samuel P. Huntington, The Clash of Civilizations and the…, 346

Categorization

• XREF: The us/them rule-splitting parallels the in-group/out-group moral psychology discussed in other readings on tribalism and moral foundations.
• SEED: Angle for an article: how dual moral codes toward insiders and ‘barbarians’ persist in modern international law and humanitarian exemptions.