Functions, Validity and the Strong Natural Law Thesis

[Extract] It has long been generally accepted that law is a kind of human artefact. However, only recently have legal theorists systematically applied philosophical work on the metaphysics of artefacts to explore the nature of law. When I first started researching this area around 2011, there was very little jurisprudential work on the topic.1
1 A notable exception is Kenneth M Ehrenberg, ‘Defending the Possibility of a Neutral Functional Theory of Law’ (2009) 29 Oxford Journal of Legal Studies 91.
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However, the metaphysics of legal artefacts has since been considered in detail by authors including Ken Ehrenberg, Luka Burazin, Corrado Roversi and myself.2
2 See, for example, Kenneth M Ehrenberg, ‘Functions in Jurisprudential Methodology’ (2013) 8 Philosophy Compass 447; Jonathan Crowe, ‘Law as an Artifact Kind’ (2014) 40 Monash University Law Review 737; Kenneth M Ehrenberg, ‘Law as Plan and Artefact’ (2016) 7 Jurisprudence 325; Luka Burazin, ‘Can There Be an Artifact Theory of Law?’ (2016) 29 Ratio Juris 385; Corrado Roversi, ‘Legal Metaphoric Artifacts’ in J Stelmach, B Brozek, and Ł Kurek (eds), The Emergence of Normative Orders (Copernicus Center Press 2016).
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Ehrenberg has now published a book-length exploration of the issue.3
3 Kenneth M Ehrenberg, The Functions of Law (Oxford University Press 2016). Page references to this book appear in parentheses in the text.
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Ehrenberg’s book focuses particularly on the role of functions in artefact theories of law. A recurring theme in the book is the need for caution in drawing jurisprudential conclusions from accounts of law’s function. In particular, Ehrenberg cautions repeatedly against what he sees as a common mistake in this area: namely, failing to allow for the conceptual possibility that law can fail in its function (45, 60, 68–69, 87, 102, 125, 180). This, he suggests, is the fatal flaw in theories that defend what Mark Murphy calls the ‘strong reading of the natural law thesis’:4
4 Mark C Murphy, Natural Law in Jurisprudence and Politics (Cambridge University Press 2006) 10–11.
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the claim that a law that is not backed by decisive reasons for action is no law at all (70, 102). I will henceforth refer to this claim as the strong natural law thesis.