The Un-man

To say in blunt words what an un-man is not particularly hard: it is a man who does not correspond to the concept man, as the inhuman is something human which is not conformed to the concept of the human. Logic calls this a "self-contradictory judgment." Would it be permissible for one to pronounce this judgment, that one can be a man without being a man, if he did not admit the hypothesis that the concept of man can be separated from the existence, the essence from the appearance? They say, he appears indeed as a man, but is not a man.