 A fifth and final form of essentialism is even more clearly Aristotelian. Here, an explicitly normative status is conferred on the set of properties to the development of which human organisms tend. For normative essentialism, “the human essence” or “human nature” is a normative standard for the evaluation of organisms belonging to the species. Where the first, third and fourth uses of the expression have tended to be made with critical intent (for defensive exceptions, see Charles 2000: 348ff.; Walsh 2006; Devitt 2008; Boulter 2012), this fifth use is more often a self-ascription (e.g., Nussbaum 1992). It is intended to emphasise metaethical claims of a specific type. According to such claims, an organism’s belonging to the human species entails or in some way involves the applicability to the organism of moral norms that ground in the value of the fully developed human form. According to one version of this thought, humans ought be, or ought to be enabled to be, rational because rationality is a key feature of the fully developed human form. Such normative-teleological accounts of human nature will be the focus of  section 5.2.