Anxieties about the creation and destruction of human embryos for the purpose of scientific research on embryonic stem cells have given a new urgency to the question of whether embryos have moral rights. This article uses a thought experiment involving two possible worlds, somewhat removed from our own in the space of possibilities, to shed light on whether early embryos have such rights as a right not to be destroyed or discarded . It is argued that early embryos do not (...) have meaningful interests or any moral rights. Accordingly, claims about the moral rights of embryos do not justify restrictions on stem cell research. (shrink)