 Other accounts of species-specific flourishing have been considerably more abstract. According to Hursthouse, plants flourish when their parts and operations are well suited to the ends of individual survival and continuance of the species. In social animals, flourishing also tends to involve characteristic pleasure and freedom from pain, and a contribution to appropriate functioning of relevant social groups (Hursthouse 1999: 197ff.). The good of human character traits conducive to pursuit of these four ends is transformed, Hursthouse claims, by the addition of “rationality”. As a result, humans flourish when they do what they correctly take themselves to have reason to do—under the constraint that they do not thereby cease to foster the four ends set for other social animals (Hursthouse 1999: 222ff.). Impersonal benevolence is, for example, because of this constraint, unlikely to be a virtue. In such an ethical outlook, what particular agents have reason to do is the primary standard; it just seems to be applied under particular constraints. A key question is thus whether the content of this primary standard is really determined by the notion of species-specific flourishing.