My article, "Differing Vulnerabilities: The Moral Significance of Lockean Personhood", has now appeared in the American Journal of Bioethics (AJOB - Neuroscience), as one of several responses to a major new article on neuroscience and personhood that appears in this issue of AJOB. My article is a (slightly qualified) defence of Locke's concept of personhood and its deployment in much contemporary work in practical ethics - as in the writings of Peter Singer, for example. By "Lockean personhood", I mean a cluster of related psychological properties that includes rationality, self-consciousness, and awareness of oneself in time (as a being with a past and a future).
I argue that what makes this cluster of properties so important is its relationship to certain kinds of vulnerability that we respond to sympathetically. Creatures that are sentient, but are not persons, cannot be vulnerable in these particular ways - e.g. they cannot experience having their hopes for the future shattered by misfortune, because they are unable to form such hopes. (Entities that are not even sentient most definitely cannot be vulnerable in such ways.)