All sentient species are biologically programmed to attack alien enemies. Some species are programmed to attack their own members as alien enemies. Rats, for example, will attack, kill, or even cannibalize one another under conditions of overcrowding and deprivation. But human beings are more unique still. Only human beings are capable of self-destruction, of suicide, of acts that have their own self-obliteration as a conscious purpose.

Human beings must view themselves as alien enemies to be able to do this. They must believe that if they allow this alien enemy to exist, it will destroy them. And so to avoid destroying themselves they destroy themselves.

We can see why this might be so. We do not know ourselves very well. Often we feel assaulted by unacceptable thoughts and impulses, and move to suppress them; or shamed by unacceptable physical features, and work to remove them; or threatened by others’ unacceptable behavior or appearance, and to attack or reject them. We view these things as alien enemies, not as the familiar ingrained parts of ourselves they are. And so we are constantly moved to destroy and reconstitute ourselves in conformity with our truncated and distorted self-image.

In all these case, and others like them, we fail to recognize that we are destroying ourselves. And so our centrally motivating urge to self-destruction itself goes unrecognized. Perhaps we wouldn’t recognize this particular facet of ourselves if it stared us in the face.