Is what we ought to do strongly related to the kind of beings we are? At the level of social roles, it seems reasonable, or at least plausible, to answer ‘yes’. If a person is a firefighter, then they ought to extinguish fires. If a person is a cobbler, then they ought to make or mend shoes. If a person is a university lecturer, then they ought to research and to teach. Yet if these answers are plausible, isn’t it also plausible to think there are norms which flow from our very nature, viz. our nature as human beings? Norms, that is, which transcend and govern us, irrespective of our social role?

We are, after all, not a species of plant, so it would be unaccountable if a human person had as their greatest ambition to feed themselves and to grow to a certain height. That might be good, but it doesn’t seem good enough: humans are ordered to a range of goods that are more complex and, as it were, outstrip the goods of plant life. And the same might be said for the goods that inform any non-human animal life: while these transcend the goods that condition mere vegetative flourishing, they still fall far short of the goods available to human animals. No chimpanzee or even dolphin, for instance, has written a symphony or designed a rocket.

The idea that norms flow from nature has ancient roots. With its beginnings in Plato and Aristotle, it reached further articulation among the Stoics. It then formed the bedrock of mediaeval moral theory, being given definitive shape by Thomas Aquinas. The traditional name for such theory is ‘natural law’, conveying the notion that there are objective laws or norms that are grounded in different species-natures. I’m fascinated by the natural law tradition in ethics, and am convinced that it can afford great wisdom, even if that wisdom needs to be re-elaborated and re-fortified in every age. What challenges does it face in ours?

Perhaps the oldest challenge goes back to David Hume, who maintained that no purely non-evaluative claim (or ‘is’ proposition) entails an evaluative claim (or ‘ought’ proposition). Yet if so, how can being the member of a particular species entail claims about what is good about or good for you? This challenge was subsequently reformulated by G. E. Moore, and is addressed by Jennifer Frey in my Cambridge Companion to Natural Law Ethics. I believe, with her, that this challenge is defeasible, partly because no salient claims about nature are ever purely non-evaluative in the first place.

A further challenge originates with Charles Darwin, who argued that the kind of teleological or end-directed conception of nature on which natural law ethics rests has been disproven by the theory of evolution. According to Darwin’s theory, the finality or purposiveness which natural species display is only ever apparent, and can be explained exhaustively by the random processes of ‘natural selection’. This is a radical and significant challenge, and stands in need of careful unpacking. Edward Feser provides this in his chapter on neo-Aristotelian metaphysics, drawing on the latest research into teleological essentialism.

Whatever challenges it faces, however, natural law ethics itself remains a highly challenging and robust approach to the moral life. Unlike some ethical theories, it does not shy away from human animality or embodiment, and responds to the objective and felt need for a philosophical anthropology. I will be elaborating my own theory of natural law over the coming months and years, and I invite everyone to get involved in the exciting debates which it inspires …