One psychological trait found in combat, and in civil violence as well, is what might be called “otherness,” that is, the emotional process of differentiating between we and they. This is a very old, very common habit of mind that certainly goes back to tribal societies and likely even further into our past. In its simplest military construct, it works this way: Before killing another person, you must first see and define them as an other, somehow essentially different from you and an enemy, a threat—real, potential, or even imagined—to you, your family, your group, your unit, your home, your nation, your homeland (a term that, not incidentally, only came into common use in America in the aftermath of the terrorist attacks on September 11, 2001). Otherness is the foundation of racism, of ethnic hatred and violence, of vendettas, feuds, religious wars, and the atrocities that so often accompany them.
To destroy other people, it also seems psychologically necessary first to define them as inferior or worthless or dangerous: It was long a commonplace among the Japanese to regard the Chinese as subhuman. In America, slavery was justified (and fought for) by those who benefitted from it—economically and socially—largely because African Americans were widely regarded as an inferior race. In all too many places in our world, these attitudes are prelude to ethnic “cleansing.”
As a habit of mind, otherness may well arise from some alligator region of our brains, but it is so common that the pattern of differentiation resides visibly in the very grammar of our language. Think of the whole vocabulary of disparagement on the basis of otherness—from Kraut to gook, from redskin to wop. Hitler understood how to wield the weapon of otherness so well that Nazi Germany’s Holocaust became rationalized and systematized beyond mere Teutonic thoroughness well into the region of madness.
Wars start for many reasons, as military history demonstrates: for territorial expansion, resources, riches, commercial advantages, and political power. Otherness may not be a primary motive for going to war, but it is, historically speaking, nearly always a catalytic factor, an accelerant, rather like flinging gasoline on an already sparky social or political conflict. It does not explain wars, but many wars, past and present, cannot be fully understood without understanding otherness.
—Michael W. Robbins