Often we are commanded directly by threat or didactically through the judgment of others to act humanely. What is threatened? What is being judged? Your essential nature, a secularized soul, that is grounded in the assumed qualities of what forms a human; to act in a way that is inhumane is to risk your status as a human. As you deny the rights guaranteed humans, so you go on to deny your own humanity in the eyes of others.
For example, consider what you have thought and have heard others say about arraigned killers -- all acts become permissible in conversation against the dehumanized "it" that was once a person. Our own behavior reveals a startling irony. We go about requesting the decency of being humane, to subscribe to the core properties that compose a human as a full social being, but how can one request a nature?
A nature is static, permanent and self-sufficient, producing a deterministic teleology. The very request to be humane, to subscribe to a type of humanism, tacitly reveals there is no nature. For how do you request a person to choose his or her nature? There is not a human soul, a human nature, or a true humanism in which to subscribe to. The request uncovers a nothingness in the human. His obsessive concern with being human points to his true composition. He is paradoxically naturally unnatural. The nothingness as if a vacuum hungrily sucking up anything in the outside world to fill it and form it into something more tangible to humanity. Humanism, those that request you be humane to others, it comes from the initial nothingness of the person that desperately seeks out something.
Did I just tell you to go out and slaughter everybody because there is no humanism to build a system of rights and ethical behavior? Unfortunately for the more violent members of our species, no. A denial of human nature and the revelation that humanity's core is a "nothingness seeking outward" allows for a host of new ways for humans to relate. A more truthful analysis and thus a better practice concerning daily human interactions can be achieved if we rid ourselves of the abstractions in the humanism of nature and right. Has it not been so dishonest that we acknowledge a worldly humanism, but at the first opportunity, tear our enemy's children into bloody ribbons and excuse it with the call "war"? Isn't the idea of world love between all nations so insincere it is nauseating? A truer understanding of humanity allows for something like a love to exist in a purer sense. Love can exist without a humanism though that may sound strange. Love is actually strangled and blinded by the false notions of a human nature. To end a sham marriage, two lovers must reveal their true "selves" to each other -- that they are both grasping nothings desperate to be affirmed by each other -- and human touch becomes more real than it has ever been before.