I meant to link earlier to this piece from the NYT Opinionator blog by philosopher Jeff McMahan. He poses the following question:
Suppose that we could arrange the gradual extinction of carnivorous species, replacing them with new herbivorous ones. Or suppose that we could intervene genetically, so that currently carnivorous species would gradually evolve into herbivorous ones, thereby fulfilling Isaiah’s prophecy. If we could bring about the end of predation by one or the other of these means at little cost to ourselves, ought we to do it?
McMahan concedes that we lack both the knowledge and wisdom to carry this out, but he speculates that we may have it one day and that decisions about which animal species to save and which to allow to become extinct may be forced on us by our ever-increasing environmental footprint. He argues that it makes sense to see carnivorous predation as a “flaw” in nature, one that we would–other things being equal–be better off without.