In recent discussions over humanism(s) and philosophical anthropology, I figure I should address my own feelings on these subjects in a more direct way (aka less critical). There have been several attempts to advance a non-anthropocentric anthropology of recent. Bernard Stiegler's first volume of Technics and Time (hey, OOP people, what are your thoughts on Stiegler?) is a move in this direction. Judith Butler has said in interviews that her most recent work is also a move in this direction. Kvond has a fairly long post on Virno's recent attempt at such a trajectory, in Virno's essay “Natural-Historical Diagrams: The New Global Movement and the Biological Invarient” (both are worth reading, EDIT though I have reservations to Virno's conclusions, which I hope to get to later). I continue to remain skeptical of the success of all these projects, even if I have benefited philosophically from all of them. My own view has been that such a philosophical anthropology remains unnecessary and potentially harmful. I tried to advance something of this argument before in my post on Species Trouble.
I certainly do not deny differences between human animals and other animals. What I deny is The Difference. The Difference is the borderline drawn that will finally demarcate The Human, that will finally let us know what it means to be human as opposed to, well, everything else in existence or ever in existence. We will finally The Difference that will hold in common every being we determine to be human while managing to hold every other being as different from this human common.
So we have differences, probably a countless and irreducible number of them. Just as there is a difference between me and you, there exists differences between us and my cat in the other room. And sometimes my cat and I can be different from anyone reading this blog. Multiple differences refuses any determinate nature. To say someone is a human or a cat is ultimately a convenience, not a philosophical fact (either ontologically or ethically). I remain fundamentally confused why I need anything more.