 Not all writers on moral status treat it as both a threshold and range concept. Both features of the concept have been challenged, and the concept itself has been criticized as hierarchical and elitist (Birch 1993). Several philosophers have argued for treating moral status as a matter of degree, so that a being’s moral status varies proportionately with its morally-relevant attributes (Perring 1997; DeGrazia 2008). These proposals avoid uncomfortably sharp dichotomies, but they have a revisionary character. Even if commonsense morality recognizes some gradations in moral status, well-established social practices such as animal research assume discontinuities. Moreover, even if common sense could be reconciled to gradations below the threshold (which would thereby become less of a threshold), it would balk at recognizing gradations above it, thereby abandoning moral status as a range concept.