The total longitudinal form view of human beings is a metaphysical view which aims to locate our moral judgements about human embryos in a broader set of attitudes and characterisations. On this basis it has explanatory power and a real function in that it grounds our ethical discussion of embryos in other discourses. Contra Leavitt, this grounding suggests a broader criterion of relevance for metaphysical discussion than asking 'what comes out of' such a discussion for a particular ethical dilemma.