Aristotelian AI Ethics, Part V: AI Ethics and Common Good Constitutionalism

Risks of a Metaphysical Revival in an AI-Driven Society

In the essays in this series, I have explored the possibility of recovering aspects of Aristotelian moral philosophy for the age of AI, especially those features that emphasize practical wisdom, human flourishing, and the cultivation of virtues in techno-moral life. But any such recovery must proceed with great care. For Aristotelian metaphysics is not a free-floating set of intuitions; it is a comprehensive picture of reality, grounded in concepts that contemporary science has, for the most part, decisively rejected. An operative assumption here is that it makes little sense to ground moral reasoning in a metaphysics that is at odds with contemporary science, particularly in a field of applied ethics like AI Ethics. This view puts pressure on Aristotelian AI Ethics to demonstrate that it is consistent with the physics that underwrites the sciences that make artificial intelligence possible. And, if Aristotelian ethics and politics are to survive the obsolescence of classical teleological metaphysics, then an Aristotelian legal theory must also confront its metaphysical debts.

This essay examines a recent attempt to revive a full-throated Aristotelianism in constitutional law: Adrian Vermeule’s Common Good Constitutionalism (Cambridge: Polity, 2022). Vermeule argues that American constitutional interpretation should be grounded in classical natural law, a tradition rooted in Aristotle, Aquinas, and the Roman jurists. On this view, law is an ordinance of reason ordered to the common good, and political authority is justified not by procedural legitimacy but by its role in directing the polity toward its telos. This is a counter-revolutionary vision, explicitly rejecting the modern liberal legal order and calling instead for a jurisprudence animated by the objective moral order of nature. But does this vision survive contact with modern science? Can a legal theory rest on metaphysical foundations that contemporary physics and biology have largely abandoned?

The risks multiply when we ask whether CGC can serve as the foundation for a constitutional vision of a society increasingly shaped by artificial intelligence. If CGC is grounded in an anti-scientific metaphysics, then using it to steer the development of AI governance may result in policies and legal structures that misalign with the very material and informational structures they seek to regulate. In such a future, the normative force of the law could be undermined not by relativism but by its metaphysical disconnection from the realities of the systems it governs.

In what follows, I argue that Common Good Constitutionalism (CGC) suffers from a fundamental incompatibility with the scientific worldview. If the Aristotelian metaphysics that underpin natural law theory are scientifically untenable, then CGC’s normative claims lack the ontological grounding they purport to possess. As a result, CGC risks becoming a species of moral idealism untethered from empirical reality, and dangerously inadequate as a framework for governing the socio-technical transformations AI is unleashing.

I. Teleology After Shannon and Darwin

Vermeule’s theory depends on the idea that human beings, like all natural entities, have a clear nature (ergon) and an intrinsic end or purpose (telos). The task of law is to guide individuals and communities toward the realization of this end, which is identified with the common good. This is not simply a theory of governance but a metaphysical anthropology: it posits a fixed human nature, discoverable by reason, which defines the objective conditions of flourishing.^[2]

Yet contemporary science offers no support for such teleological assumptions. As was explained in Part I of this series, developments in mathematics, logic, and physics in the early twentieth century called into doubt the viability of the Aristotelian metaphysics. Neither form nor substance is fixed, and therefore, a metaphysics of form and substance (hylomorphic) came to be seen as naïve realism. This fundamental shift toward relational realism was given support by the development of information science, which has transformed basic sciences. An Aristotelian moral anthropology seems impossible to reconcile with contemporary biology, which explains the structure and function of organisms through informational descriptions of natural selection acting on heritable variation. The eye does not exist because it fulfills a natural end of sight; it exists because its precursors conferred a reproductive advantage in certain environments. As Ernst Mayr argued, biology has replaced final causes with functional analysis (and more recently, these functional analyses are described in terms of binary information. Functionality is understood in terms of information, not fulfillment.^[2]

In physics, the situation is more acute. Contemporary physics no longer describes the universe not as a hierarchy of substances with fixed essences. It is a complex system of relations, fields, and symmetries. The metaphysical categories of Aristotelianism simply do not appear in the ontological furniture of quantum field theory and the General Theory of Relativity. As James Ladyman and Don Ross emphasize, any metaphysics worth its salt must be informed by our best empirical science, not by a priori intuitions inherited from pre-modern thought.^[3]

CGC, by contrast, assumes that the universe has a moral structure, accessible to reason, and that this structure includes normative ends embedded in the nature of things. This assumption is not merely unscientific; it is anti-scientific, in that it posits explanatory entities that science has systematically excluded.

II. Natural Law Without Nature?

For Vermeule, law does not derive its authority from popular sovereignty or procedural legitimacy but from its alignment with the natural law. This natural law is a rational ordering of creation, reflecting the ends proper to human beings. It binds all positive law, including constitutions, which must be interpreted in light of their contribution to the common good.^[4] But if nature, as understood by science, contains no teleology, then what does natural law refer to? It becomes, at best, a moral tradition, not an objective law of nature in any scientifically credible sense. From the standpoint of scientific naturalism, the moral order posited by natural law theory is not discovered but projected. It expresses human value judgments, shaped by history and culture, but it does not derive from the structure of the universe.

This critique does not deny the legitimacy of moral reasoning. It merely insists that such reasoning must not disguise itself as physics. The risk, as Ladyman and Ross put it, is that metaphysics becomes "folk metaphysics": a reconstruction of pre-scientific intuitions in the language of law or theology.^[5] CGC, in its insistence on a fixed human nature and a universal moral order, is vulnerable to precisely this charge.

III. Metaphysical Anachronism and Legal Theory

In Everything Must Go, Ladyman and Ross mount a sustained critique of traditional metaphysics, particularly those forms that rely on conceptual analysis and intuition rather than scientific evidence. They argue that many central concepts in analytic philosophy—such as substance, causation, and modality—lack empirical content and should be replaced by metaphysical frameworks grounded in physics and information theory.⁵

From this perspective, Vermeule’s call to return to a jurisprudence rooted in Aristotelian metaphysics is not just outdated; it is methodologically irresponsible. It treats as foundational concepts that science has either redefined or discarded. In the legal context, this critique extends to theories like CGC that depend on those very concepts to justify authority, interpret texts, and adjudicate rights. Legal theorists are not required to be physicists. But when they invoke nature to ground normative claims, they incur an epistemic debt: they must show that their account of nature is not in conflict with our best scientific understanding. CGC does not pay this debt. Instead, it trades on an image of nature that is theological rather than empirical.

IV. Tasioulas and the Liberal Interlocutor

To be fair, not all critics of CGC approach it from a scientific standpoint. John Tasioulas, for example, offers a powerful critique from within the tradition of humanistic jurisprudence. In his review essay "Law as the Art of Justice," Tasioulas acknowledges Vermeule’s important intervention but questions his rejection of liberalism and legal positivism.⁶ Tasioulas defends a version of natural law theory that is compatible with some liberal commitments, particularly the idea of individual dignity and the value of procedural fairness. He also resists Vermeule’s strong anti-positivism, suggesting that legal validity and moral correctness can diverge without collapsing into nihilism. Most importantly, he argues that CGC risks reducing legal reasoning to moral fiat, thereby undermining the autonomy of law. While Tasioulas does not invoke the language of scientific naturalism, his critique converges with mine in a crucial respect: both reject the reification of metaphysical constructs as legal foundations. For Tasioulas, the problem is a moral overreach; for me, ad for Ladyman and Ross, it is a metaphysical one. But both critiques call for a jurisprudence that acknowledges the pluralism and contingency of modernity.

V. Ordo Amoris and the Relational Turn

In a previous essay, I proposed that a resource for thinking about a relational ethics could be rooted in ordo amoris. Augustine’s idea that love is the organizing principle of moral life offers a way of speaking about the good without presupposing a fixed metaphysical order.

This approach aligns more closely with the complex systems perspective emerging in contemporary science. Here, meaning and value are not given once and for all but arise through dynamic interaction, emergence, and self-organization. Such a framework does not require us to believe in essences or natural kinds; it invites us to understand law and ethics as evolving practices embedded in social and informational ecologies.

Rather than ask law to conform to an outdated ontology, we might instead seek a legal theory that is responsive to relational complexity, moral pluralism, and epistemic humility. This does not mean abandoning the search for justice. It means rethinking what it means to pursue the common good in a world that no longer believes in fixed ends. Ironically, this seems to be an idea that Vermuele once nearly reached, in his earlier works, Law and the Limits of Reason (2008) and The System of the Constitution (2011).

VI. Conclusion: The Future of Legal Metaphysics

To summarize, I have argued that Common Good Constitutionalism seeks to reassert a moral foundation for law, one that transcends liberal proceduralism and grounds legal authority in the pursuit of human flourishing. But its reliance on Aristotelian teleology places it at odds with the scientific image of the world. If we take that image seriously, as Ladyman and Ross urge, then CGC's metaphysical foundations are no longer credible.

This does not mean we must embrace legal nihilism. But it does mean that any serious theory of law must align with modern science for its understanding of nature, personhood, and normativity. We may still speak of the common good, but only if we are willing to reconceive it as an emergent, relational, and pluralistic aspiration, rather than a fixed end embedded in the order of things.

Footnotes

1. Adrian Vermeule, Common Good Constitutionalism (Cambridge: Polity Press, 2022); see also Conor Casey, "Classical Natural Law, Common Good Constitutionalism, and Constitutional Change," SSRN (2024), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4939257.

2. Ernst Mayr, Toward a New Philosophy of Biology (Cambridge, MA: Harvard University Press, 1988), 38–64.

3. James Ladyman and Don Ross, with David Spurrett and John Collier, Every Thing Must Go: Metaphysics Naturalized (Oxford: Oxford University Press, 2007), 28–64.

4. Vermeule, Common Good Constitutionalism, 30.

5. Ibid., 125–189.

6. John Tasioulas, "Law as the Art of Justice," SSRN (2023), https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4328575