Natural concepts have fuzzy edges, whether it’s “person” or “human.” I don’t decide the boundaries of those concepts. I’m just analyzing the concepts that seem relevant to determining how morality arises from nature without the benefit of any supernatural cause.

So if some folks have some but not all the properties of personhood or humanity, they may have only some of the corresponding rights and responsibilities, depending on the importance of those properties that are missing. A continuum of rights would go with a continuum of the relevant properties of the subjects that are supposed to be regulated by moral standards.

Society decides what to do with marginal individuals. Liberal societies err on the side of caution and tolerance, whereas authoritarian ones would eliminate many of those marginal cases, based on conformity to a rigid set of ideals. For various reasons, I support liberal, humanistic societies.