The main objection to human embryonic stem cell research is that it involves killing human embryos, which are essentially beings of the same sort that you and I are. This objection presupposes that we once existed as early embryos and that we had the same moral status then that we have now. This essay challenges both those presuppositions, but focuses primarily on the first. I argue first that these presuppositions are incompatible with widely accepted beliefs about both assisted conception and (...) monozygotic twinning. I then argue that we never existed as embryos. If this last claim is right, killing an embryo does not kill someone like you or me but merely prevents one of us from existing. (shrink)

Most philosophical accounts of human rights accept that all persons have human rights. Typically, ‘personhood’ is understood as unitary and binary. It is unitary because there is generally supposed to be a single threshold property required for personhood. It is binary because it is all-or-nothing: you are either a person or you are not. A difficulty with binary views is that there will typically be subjects, like children and those with dementia, who do not meet the threshold, and so who (...) are not persons with human rights, on these accounts. It is consequently unclear how we ought to treat these subjects. This is the problem of marginal cases. I argue that we cannot resolve the problem of marginal cases if we accept a unitary, binary view of personhood. Instead, I develop a new non-binary personhood account of human rights, and defend two main claims. First, there are many, scalar properties, the having of which are conducive to personhood. Second, different subjects have different human rights depending on which of these properties they have, and what threats apply to them. On my view, and contra most existing accounts, most marginal cases have some degree of personhood and are entitled to some human rights. (shrink)