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The Oxford Handbook of the Theory of International Law edited by Orford, Anne; Hoffmann, Florian (2nd June 2016)

Part II Approaches, Ch.14 Natural Law in International Legal Theory: Linear and Dialectical Presentations

Geoff Gordon

From: The Oxford Handbook of the Theory of International Law

Edited By: Anne Orford, Florian Hoffmann

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 23 October 2019

Customary international law — General principles of international law — Relationship of international law & host state law — Sources of international law

(p. 279) Chapter 14  Natural Law in International Legal Theory

Linear and Dialectical Presentations


Natural law has a peculiar way of being everywhere and nowhere in the body of international law today. Often taken to be in some way foundational of positive law,1 and traditionally accepted to declare positive law either void or defective in any given case,2 its applicability in theory has been widened to the point of near-ubiquity by association with both naturalism, on the one hand, and the (p. 280) rhetoric of justice on the other.3 Yet it is hardly to be found in practice,4 and has been described as dead.5 In addressing such a diffuse and conflicted field, choices are necessary and omissions inevitable. Some will be unconventional. I propose here to tell two stories about natural law in international legal theory, both roughly organized around a meeting point of sorts for the associations with naturalism and justice. This will also function as a brisk overview, drawing on three active periods of natural law scholarship bearing on international law, as well as recent developments.

The first story relates in brief the renewed attention to natural law doctrine as part of historiographical and epistemological inquiries in international law and legal theory, with particular attention to the foundational role of natural law doctrine in a hegemonic project.6 The second presents still another means of understanding natural law and its ongoing role in international law, namely as a dialectic by which new conceptions and vocabularies of political organization have arisen under varying historical circumstances.7 The dialectical presentation, however, is not to the exclusion of the linear presentation of consolidating global hegemony, but fits within or alongside it.

This may seem contradictory. But it is emblematic of the unusual role between hegemony and resistance played by international law,8 and reinforces the (p. 281) foundational character of natural law in international legal theory. Umut Özsu writes of dialectical analysis in international law as potentially ‘capable of explaining how international law is hardwired in ways that systemically disempower less resourceful actors while permitting these same actors to wage struggles of emancipation in its name.’9 The ambition here—applied specifically to natural law, and limited to a brief outline with an eye towards further study—is similar: to demonstrate how natural law continues to inform efforts—both hegemonic and counter-hegemonic—to define a foundation and telos for the international system.

In this chapter, I turn first to an overview of three active periods of natural law scholarship bearing on international legal theory. I then trace in brief the role of natural law doctrine as part of a linear consolidation of liberal hegemony internationally from the early modern period forward. Thereafter, I offer the dialectical presentation covering the same timeframe. In closing, I will return to how natural law continues to contribute both to the possibility of new normative programmes internationally, as well as the hegemonic.


Different instantiations of natural law doctrine are closely bound up with two origin stories of modern international law. First, the doctrine of the neo-scholastics of the Salamanca School contributed to one supposed birth of the modern international system, coincident with the Peace of Westphalia.10 Second, an adaptation of natural law—the so-called law of nature—established the foundation of Enlightenment liberalism, and the mindset that ultimately produces the label of international law, attributed to Jeremy Bentham.11 The different doctrinal instantiations reflect different aspirations to the universal, joined to different appreciations of the political. In the following section, I turn first to the period of Vitoria through Grotius, thereafter to a formative period of Enlightenment liberalism,12 (p. 282) and I conclude this section by turning to adaptations of natural law theory made by twentieth-century figures.

2.1  Vitoria through Grotius

Vitoria, working at the University of Salamanca in the early sixteenth century, helped to found what has come to be known as the Salamanca School in a period of disintegrating religious and social cohesion among the peoples of Europe. At the same time, the world was expanding as a function of the exploration and exploitation of the new world, further stretching the viability of norms and bonds that had historically anchored rules of conduct among European peoples. Against these trends, Vitoria operated in an official environment still defined by consolidated political authorities associated with the Holy Roman Empire and the Catholic Church.13 To provide for normative cohesion across peoples in the face of social disintegration, coupled with competition to subjugate an expanding world, Vitoria adapted the natural law doctrine of Thomas Aquinas together with vestiges of the Roman jus gentium.14 Vitoria’s adaptation was significant for the new vision of the political community to which it was joined. His doctrine reflected a normative potential vested in a comprehensive phenomenon of human collectivity, not identified with imperialist authorities, and also distinct from—but inclusive of—new and independent peoples.15

Vitoria characterized comprehensive collectivity in terms of interdependence among the people and peoples of the world.16 The interdependence that he observed flowed from an Aristotelian appreciation of natural social inclinations and a universal capacity to communicate, to the effect that ‘[n]‌ature has established a bond of relationship between all men’.17 The roots in a natural, comprehensive collectivity established an objective foundation for law in the new context of international relations, and reliance on sociability entailed an immanent condition of interconnection by which to comprehend ‘the common good of all.’18 In this way, (p. 283) Vitoria envisioned the human community as a discrete collective entity with interests and ends of its own—not to the exclusion of the particular collective such as the state, but in addition to it.19 The difference was that the subjective authority of the nation-state would yield before the consolidated norms of the world collective within the latter’s proper areas of interests or ends.20 Likewise, the normative order of the natural whole would be objective for flowing from the thing itself, rather than any subjective aspiration to define it.21 That objective foundation served as a counterforce to rising political independence among discrete national collectives, even as it liberated them from the regimes of Emperor and Pope; it supported a consolidated statement of authority intended to sustain norms of conduct—both natural and positive—across increasingly independent peoples, but without subjecting them to imperial control in the form of any singular potentate.22

Following Vitoria, Suárez, also in Salamanca for a time, took further the interdependent underpinning of Vitoria’s social vision. He joined Vitoria’s statement of natural law to an emphasis on underlying political unity: ‘the human race, into howsoever many different peoples and kingdoms it may be divided, always preserves a certain unity’.23 Unity reinforced universality: ‘although a given sovereign state, commonwealth, or the kingdom, may constitute a perfect community in itself, consisting of its own members, nevertheless, each one of these states is also, in a certain sense, and viewed in relation to the human race, a member of that universal society’.24 Suárez observed the universal society, in turn, to give rise to ‘true law’, discernible in norms of conduct evidenced by the ‘whole world’.25

After Suárez, Grotius has also been described as a last member of the Salamanca School,26 though he has, at the same time, been understood as the starting point for what follows in the period of Enlightenment liberalism.27 I focus here on commonalities with the Salamanca School. Grotius, like Vitoria and Suárez, subscribed to an idea of a ‘society of mankind’ or ‘human society’ encompassing humanity as a whole.28 He founded that society in both natural and empirical roots. Grotius’ world society—and the natural law applicable to it—arose naturally out of the universal capacity for and inclination to sociability and communication, together (p. 284) with the fact of interdependence.29 He described the natural wellspring of universal norms as follows: ‘This Sociability … or this Care of maintaining Society in a Manner conformable to the Light of human Understanding, is the Fountain of Right, properly so called’.30 In addition, Grotius’ natural law included a right to intervene, in the name of human society, in particular cases of injustice.31 Thereby the natural law affirmed universal rights of human society capable of trumping any particular right vested in smaller social and political collectives.

Notably, however, the Salamanca School’s doctrine of interdependence and collective unity included endorsements of commerce and private property under law.32 The natural unity founded on social inclinations included a universal right among individuals to trade, which established grounds justifying colonial exploitation and the aggrandizement of particular interests vested in colonial powers.33 The common good was held to include a personal right to private property, comprehended according to tenets associated with commutative, rather than distributive justice.34 As a consequence, the affirmations of trade and private property implicitly privileged individualism, together with competition and acquisition, in the interrelationships making up the universal collective in theory. That allowance for acquisitive individualism, despite the Salamanca School’s driving concern with the possibility of national atomization in a world not defined by emperor or pope, suggests a compromised doctrine, one that aspired to communal objectivity, but was conducive to the competitive subjectivity that ultimately came to define international law established among the colonial powers.

But though elements of the ultimate failure of the Salamanca School’s pretension to a harmonious basis in natural law for international norms were present from the start, the political concept underlying the School’s application of natural law to international legal theory nonetheless bears appreciating in historical context.35 It was a concept that altered the dominant political image of the time, the body politic, understood by analogy to the human body as an organic but differentiated whole. The Salamanca School disassociated the unitary body politic from its human instantiation, otherwise understood to be literally vested in the figure of the sovereign, and reconceived it according to a socially-constituted consciousness.36 The recourse to a socially-constituted consciousness was not new. Dante, for (p. 285) example, in De Monarchia, citing Aristotle and following the work of Ibn Rushd, relied on the idea of a collective mind belonging to humanity as a whole, as a conceptual support for world empire.37 Dante, however, still held the collective mind to affirm the authority of a singular figure, namely the emperor. An innovation of the Salamanca School was to diminish the singular figure representing conscious control over the body,38 as applied to the whole of the human community, allowing thereby a comprehensive consciousness but not a singular head. Herein, again, are roots that will be seen to conduce towards the definitive turning away from Thomist natural law in Enlightenment theory. Nonetheless, the Salamanca School reconceived the nature of the political community to project a markedly different figure of central authority, to allow for new possibilities of political organization and interaction in a changing world, while sustaining its collective coherence.39 The effect may be understood for its rejection of the hegemonic powers of the time, as well as its contribution to a different hegemonic order, as will be returned to below.

2.2  Enlightenment Liberalism and the Law of Nature

I turn now to the Enlightenment, and the move from natural law to a new law of nature. The Enlightenment, it bears noting, does not refer to a perfectly unified intellectual phenomenon, but is a label encompassing a number of competing political ideas and ambitions in Europe.40 Those ambitions were, in part, the product of the forces of disintegration against which the Salamanca School had posed its affirmation of an organic and comprehensive collective phenomenon. Thus the Reformation and Counter-Reformation gave rise to a number of competing objectives, in which competing powers of the time largely aimed at monopolizing local and regional controls, coupled to expanding colonial empires.41 The new political ambitions occurred coincident with the ascendant vocabulary of a new science, as well as a rising sentiment of bourgeois individualism.42 Thomas Hobbes mastered this new vocabulary and sentiment in the service of one particular political program and in the interests of a particular set (p. 286) of what might be called clients (namely, William Cavendish and his royalist cohorts); Samuel Pufendorf, influenced also by Hobbes’ work, did so with another vision, tied to other interests; so too with Immanuel Kant, so too with Emer de Vattel, etc.43 Below, however, I will for the most part treat these disparate programs for those characteristics in common that allow them to be treated as a group, noting differences in the text or notes where appropriate.44

Against a changed and changing social environment, the common link between the new law of nature and the old natural law was the intent to understand the norms appropriate to human persons and peoples as a function of human nature. But a new methodology was employed, represented by the ‘state of nature’ thought experiment, giving rise to a distinct political vocabulary.45 The state of nature, as is well known, posits the situation of humanity under imagined conditions of anarchy. Every member of humanity imagined to be in that situation is understood according to certain uniform attributes, including a primary interest in survival. The only means out of that situation is the social contract, the sum of so many individual, imagined acts of contract. Universal norms were no longer to be founded and understood in terms of the comprehensive collective, and a proper understanding of the body as a whole, but in terms of the individuals comprised by the collective body. Individualism, however, was not identical to diversity. The individual was the individual abstracted. The reflective and analogical method of the Salamanca School thinkers gave way to a deductive method and abstraction. The distinct pretension to universality of Enlightenment liberalism arose from the uniform representation of the individual as a common unit. Individuals were understood as equals, exhibiting a capacity for communication and an inherent self-interest, not necessarily in that order.

I begin with Hobbes. Though he is known as a proponent of or apologist for power and absolutism, and was dismissed for related reasons by Kant,46 he nonetheless was engaged in founding the authority of the monarch in the imagined authority of the people47—and their imagined ability to alienate it. The monarch (p. 287) was no longer the natural expression of authority for an organic or divinely constituted body politic; rather, the queen or king enjoyed sovereignty—however absolute—by virtue of the supposed will of the people.48 Imagined acts of contract, effecting mutual acts of alienation, established public authority.49 Public authority was no longer a natural outgrowth of an organic condition or phenomenon in the world, but an artificial construction, brought into the world by constructive acts of will.50

Though the metaphor of the body remains in Hobbes’ work, in the figure of the Leviathan, it is a figurative rendering, a product of the many acts of will that it comprises.51 If the Salamanca School represented an early move away from the corporeal instantiation of the body politic, Hobbes represented a still more definitive shift. While the Spanish School thinkers had diminished identification of the universal body with any one manifestation in the flesh, they still understood the unity of political community everywhere as an organic body. The body of the Leviathan, by contrast, is an artifice, constructed locally out of individual acts of agency.52 Thereby, Hobbes marked a radical shift in the political terms underpinning the political community: from a unitary entity to so many acts, from the organic body to the negotiated contract.

Hobbes did not initiate the change in political conditions that the Leviathan represented, but he, together with others, consolidated rising sentiment—and channelled its expression going forward, fixing the terms by which change in political community would be understood at that point in time, and establishing the vocabulary by which public authority would be invoked thereafter.53 Kant, among others, subscribed to roughly democratic change as expressed in the turn to contractual reasoning, though he disavowed Hobbes’ absolute monarch, and was at odds with various other imagined products of the social contract.54 In part, however, Kant’s disagreement with Hobbes reflects the degree to which Hobbes captured the expression of political sentiment, insofar as Kant was obliged to communicate appreciably different sentiments according to common terms of reference.

For Kant, unlike for Hobbes, the product of the act of contract represented a necessary step in a world-historical process towards a greater cosmopolitan condition, (p. 288) a comprehensive Kingdom of Ends.55 The instrumental logic that defines Hobbes’ theory is crucial also to Kant’s theory, but is not the whole of it.56 Though the ordered political community under law must in the first instance be achieved by act of contract, the act of contract establishing the sovereign state was not merely a rational choice, the goal of so many acts of self-interest, but a moral obligation as well.57 Further, the product of the act of contract was not merely ideational support for a particular community under a particular sovereign, but also knowledge of an outstanding moral obligation yet to be fulfilled, part of an ongoing project for humankind as a whole.58 In some respects, however, the rational choice had to come first, and the moral knowledge would follow.59 Conflict would drive people into pacific arrangements, which would lead to the realization of a moral imperative to perfect a just normative order.60

The interrelationship of functional and moral motives in Kant’s work underscores the degree to which Enlightenment liberal theory was deployed to support new forms of political organization, on the basis of the peculiar adaptation of natural law into the law of nature. Consider a remarkable point in Kant’s comparison of international and cosmopolitan right. International right is founded in the appreciation of the self-interest of states; cosmopolitan right is founded on an appreciation of the fundamental conditions of humanity. But international right promises world peace where cosmopolitan right cannot:

nature also unites nations which the concept of cosmopolitan right would not have protected from violence and war, and does so by means of their mutual self-interest. . . . Thus, states find themselves compelled to promote the noble cause of peace, though not exactly from motives of morality.61

The vocabulary of self-interest, joined to the rising democratic and bourgeois sensibility realized in terms of the contract, founded and gave definition to the possibility for progressive international politics, when morality was understood not to suffice. Just as the Salamanca School articulated a new political conception in an optimistic effort to capture new historical conditions for a political organization in the world, so too did Kant, together with Hobbes, ‘sorry comforter’ though the latter turned out to be.

Other sorry comforters included Pufendorf and Vattel, and they were formative in their transposition of Hobbes’ contractual premises and method to international legal theory.62 The elevation of contractual premises constrained the (p. 289) binding nature of norms in relations between states, insofar as the absence of a world sovereign indicated the failure to have moved beyond anarchic conditions of original right.63 This consigned states to the state of nature and the law that inheres in that otherwise imagined state, a condition that admits no magistrate.64 Absent a magistrate, the laws of nature were pronounced and interpreted by specialists in the esoteric science of morality comprehended according to the dominant rationality of contract.65

That science revealed a law of nature that bound sovereigns directly, but, absent the construction of a global leviathan, admitted no systemic possibility for disinterested enforcement, nor a unified basis by which to apprehend the communal good. The Salamanca School’s pretension to objective grounds for the authority was boxed into so many subjective commitments. The lack of objective grounds for enforcement likewise entailed for Pufendorf the impossibility of positive international law, allowing instead more or less prudential commitments made among sovereigns in the interests of their respective commonwealths, and backed by the moral sanction of natural law.66 In a similar but slightly less stark fashion, Vattel divided norms among necessary and voluntary law. The law of nature comprised the former, necessary law in all cases valid, but in a direct and personal way, realizable only subjectively.67 The voluntary law, by contrast, represented those rules to which sovereigns voluntarily consented among one another. The effect of the work of Pufendorf and Vattel was to coronate subjective individualism in international relations.

Though their embrace of the law of nature came to define the international system of equal and independent sovereigns, such that they have become known for a retrograde character,68 Pufendorf and Vattel also represented the new possibilities for political organization under the changing historical conditions of political relations at the time.69 Their contribution may be understood again by contrast (p. 290) with the old political imagery of the body. Understanding persons and peoples as parts of a natural body entails understanding the natural delimitations on them that are conjoint with their distinct contributions to that body.70 One part of the body is stronger than another, one suited for speaking, one suited for listening, etc. With different natural capacities comes different rights and responsibilities: suum cuique. By contrast, following the state of nature, the law of nature takes all individuals as equal. The new pretence to equality represented new possibilities for opportunity associated with a rising bourgeois class, the spread of popular and democratic sentiment, and the multiplication of wealth across parts of Europe generated by capitalism and colonialism.71 Thus the celebratory image of the giant and the dwarf as free and equal, adopted by Vattel and others:

Since men are naturally equal, and a perfect equality prevails in their rights and obligations, as equally proceeding from nature—Nations composed of men, and considered as so many free persons living together in a state of nature, are naturally equal, and inherit from nature the same obligations and rights. Power or weakness does not in this respect produce any difference. A dwarf is as much a man as a giant; a small republic is no less a sovereign state than the most powerful kingdom.72

The effect was a sharp move away from conceptual innovations of the Salamanca School, though not necessarily in the direction of retreat. The Salamanca School had reconceived a universal body politic, its guiding consciousness rendered independent of any one, figurative head. The Enlightenment liberals now gave every sovereign a subjective power to channel a guiding consciousness as the empowered head of a self-made body.

2.3  The Contemporary Turn

The end of the nineteenth and the beginning of the twentieth century witnessed a return to the natural law doctrine articulated up through the work of Grotius. Though Grotius had never really fallen out of the mainstream, Vitoria and Suárez, together with others who had not enjoyed the same level of sustained interest, were reclaimed principally by Ernest Nys, Camilo Barcia Trelles, and James Brown Scott, and deployed, in the name of a new international solidarity, against the (p. 291) reigning individualism and voluntarist positivism of the eighteenth into the nineteenth century.73 The reclamation was coordinate with a sense of growing closeness and complexity in the interrelationship among states in the international system.74 The turn back to the Salamanca School was made to address the ‘new’ conditions of international community, and solidarity was, in name, the adopted political ambition. Still, the return to the Spanish School was not greatly marked by meaningfully new doctrinal development.

The initiation of a new development in natural law doctrine arrives with a succeeding wave of twentieth-century scholars, such as Alfred Verdross and Hersch Lauterpacht. Both were students of Hans Kelsen, but, unlike Kelsen, were not content to critique the positivism of international law strictly from within his sophisticated positivist theory.75 Each purported to connect an appreciation of positivism to some grounding in natural law, repairing a split between natural and positive law that widens following the work of Pufendorf and Vattel.76 To a certain extent, this is unremarkable. As Stephen Hall and others point out, the Thomist natural law tradition of the Salamanca School, unlike the school of Enlightenment liberalism, affirms the integrated nature of positive and natural law.77 But Verdross and Lauterpacht, among others, further began to merge the recovered natural law vocabulary with a sophisticated appreciation of then-dominant terms of positivism and liberalism, to articulate a new political conception for changing circumstances of international relations. They initiated a vocabulary in which the appreciation of agency and autonomous will, still joined to contractual language, could be merged (p. 292) with an appreciation of an organic and unified whole, reminiscent of the old body politic, and representative of progressive ends. Lauterpacht wrote:

An initial hypothesis expressed in the terms of voluntas civitatis maximae est servanda would point, as the source of law, to the will of the international society expressing itself in contractual agreements between its constituent members, in their customs, and in the general principles of law which no civilized community can afford to ignore; it would refer to the civitas maxima as meaning that super-State of law which States, through the recognition of the binding force of international law qua law, have already recognized as existing over and above the national sovereignties.78

Iain Scobbie has written that a ‘natural law thesis … is the thread which runs through and unifies Lauterpacht’s work.’79 Early in his career, Lauterpacht staked out ‘the philosophical bases of international law’ in ‘the problem of relation of states to humanity’.80 In his study of Grotius, Lauterpacht referred back to Vitoria and Suárez as laying the ‘foundations of the jurisprudential treatment of the problem of the international community as a whole’.81 In Grotius, however, Lauterpacht found ‘a scientific basis—that of the law of nature and of the social nature of man—for the “volitional” law of nations’.82 Though Lauterpacht operated by reference to Grotius, he was establishing a new position for natural law as a matter of international legal theory. The turn to science underscored that new position, which reflects both classical and Enlightenment natural law theory, but was not identical to either. That new position exhibited empirical rigor, founded in ‘the social and political realities of the international community’, to rival positivism;83 it likewise sustained comprehensive political unity while simultaneously facilitating human autonomy. What Lauterpacht aimed to do, through Grotius, ‘was to endow international law with unprecedented dignity and authority by making it part not only of a general system of jurisprudence but also of a universal moral code’.84 To do so was to elevate international law and international community to the proper ends of the natural human condition.85

(p. 293) Anthony Carty’s exploration of Verdross’ early, interwar work makes clear Verdross’ desire ‘to reactivate the cultural power of a sixteenth-century Spanish catholic intellectual tradition’, a reaction against Enlightenment individualism, but not an outright rejection of its legacy in positive international law.86 Carty describes the product as an organic theory of ‘the integral association of the part to the Totality, which in turn divides itself into parts’.87 In this complex relation of part and whole, autonomous actors recognize one another by virtue of ‘a notion of potentiality, completed in community’.88 Pursuing this idea throughout his career, Verdross dedicated a later article to ‘Two Arguments for an Empirical Foundation of Natural-Law Norms’.89 There, he made clear that a re-examination of natural law was critical to an ongoing project of ‘laying the foundation to legal philosophy’.90 He asked: ‘how can social norms be ascertained from the Is of human nature’? His answer, in short, was that human nature exhibits a constant substance, but its proper expression will be a contingent one, the product of an independent will applied to uniform ends in historical context.91 The product was a complex admixture of telos, autonomy, and historicity, by which Verdross envisioned a unitary community underlying international law, discerned in conjunction with the norms that arise naturally out of the interactions of individuals everywhere at any given point in time.92

Others pursued similar projects. Pieter Kooijmans, later judge of the International Court of Justice (ICJ), turned to what he called ‘modern natural law’ in his treatise on the doctrine of the legal equality of states, which he fashioned as an inquiry into the foundations of international law.93 Kooijmans identified modern natural law with a number of contemporaneous scholars—most notably, perhaps, including JL Brierly and Raoul Padirac, as well as Verdross94—while noting that some of those included ‘themselves denied that they uphold the doctrine of natural law’.95 Nonetheless, Kooijmans identified a school of thought and distinguished it from both the Salamanca School and the Enlightenment naturalists. The new school of natural law, following Kooijmans, adhered to the Salamanca School pretension (p. 294) to an objective foundation for law in unitary community, as against the subjectivity that followed from Enlightenment liberalism, but took the objective foundation to be knowable only as a matter of historically-contingent expression.96 Thus Kooijmans eschewed ‘an eternal, unvariable natural law’ as ‘a misconception of the historical development’.97 Instead, an appreciation of human agency and change in material conditions over time led to ‘a natural law with variable content’.98

Consider as well the work of another former judge of the ICJ, Alejandro Álvarez. Though Álvarez described himself as opposed to natural law,99 his work shows all of the hallmarks of the modern natural law identified by Kooijmans: namely, a set of historically contingent norms arising naturally out of a condition of interdependence, reflecting ineluctable global solidarity in contemporary world relations.100 He did so, in part, as part of a consistent challenge to the individualist orthodoxy of voluntarist positivism, which he sustained from (and against) the bench of the World Court itself.101 In that light, Álvarez is reflective of what Arnulf Becker Lorca has made clear: that the story of the universalist project of international law, though joined to the hegemonic project, includes its exercise by international jurists situated outside of Western centres of expansive powers.102

The various links, above, between agency, historicity, and ends represent one of the primary meeting points between naturalism and justice raised at the outset. Natural law doctrine serves as a proxy statement for a comprehensive political community, a natural unity manifest in historically contingent ways, ostensibly (p. 295) perceived according to the acts and experiences of individuals and collectives in the context of material, social, and cultural conditions at any given point in time. That convergence found its most elaborate—and perhaps still most controversial—exegesis in the work of the New Haven School, which at once hardened the pretension to a scientific vocabulary, while amplifying the apprehension of a natural and unitary social dimension underlying international law.103 The New Haven School avowedly ‘use[d]‌ the expression “world community” … not in a metaphoric or wistfully aspirational sense but as a descriptive term’ (noting as well, in that use, overlap with the International Encyclopedia of Social Sciences).104 The foundation of international norms became a vast, ineluctable social phenomenon: ‘international law is part of larger world social process that comprehends all the interpenetrating and inter-stimulating communities on the planet.’105

The picture that emerged was the unitary, natural law community of the Salamanca School, but raised to a level of wild complexity meant to convey the same scientific grounding to which Lauterpacht aspired. Consider the New Haven School appraisal of the Salamanca School: ‘the early “natural” law approach, though sometimes cognisant of the larger community of humankind, more often adopted partial and unevaluated conceptions of that community and did not develop the notion of interpenetrating community processes embracing all peoples.’106 All of the foregoing suggests a vocabulary by which a collective whole may be comprehended by reference to the diversity of its constituent parts, rather than their abstracted identity, with the image of the unitary whole arising out of the sum total of acts of agency bearing on interconnectedness in the world—but arising naturally out of those acts, not as a willed or artificial construction.

The twentieth-century development has continued to evolve. Process theories, such as transnational legal process,107 and other theories adopting the insights of social constructivism,108 exhibit aspects of the new natural law in their affirmation of norms arising naturally out of ineluctable conditions of interrelationship.109 (p. 296) Norms are understood as functions of dynamic, intersubjective processes of agency and internalization in which subjects and norms are mutually-implicating and mutually-constituted. One contemporary school of thought bears noting for its express adoption and adaptation of a natural law vocabulary, namely the interactional theory of international law developed by Jutta Brunnée and Stephen Toope.110 They incorporate the natural law theory of Lon Fuller—though minimizing it as ‘weak natural law’111—applying it to international law as part of a legitimacy calculus. Fuller provided a test of ‘internal morality’, in the form of eight criteria, by which to measure law’s legitimacy.112 Brunnée and Toope join that set of universal criteria to an external test concerning a demonstration of ‘shared purposes’ across actors, which purposes will be ‘strongly rooted in specific contexts’.113 Thus the interactional theory of law proceeds in the mode of natural law thinking in international legal theory established in the twentieth century, affirming norms by observation of historically contingent purposes manifest in the interactions of interconnected actors in the world, provided those norms meet certain minimum universal standards incumbent upon the idea of law in community. I will return to still more contemporary developments later in the chapter following a brief encapsulation of the linear and dialectical stories discernible in the historical narrative thus far.

Linear and Dialectical Dimensions

As Koskenniemi has lately demonstrated—in conjunction with similar work by Anghie, Miéville, and others—natural law theory is foundational to discontents of international law and the international system.114 This historiographical narrative (p. 297) is by and large a linear one, following a singular facet of natural law doctrine over time for its role in the development of the international system. The narrative demonstrates an identity between contemporary international law and the natural law innovations of Samuel Pufendorf,115 and, working backwards, observes in the Salamanca School the roots of the liberalism that Pufendorf represents.116 In this way, the deep roots of a hegemonic enterprise may be seen to extend back to early-modern natural law doctrine.

An extremely brief and partial canvass—much of it already alluded to, and all of it done by reference to other works, including other chapters in this volume—must suffice here, however inadequate, merely to sketch some of the discontents associated with that enterprise. In the first place, in each of the historical periods observed here, natural law served to support new possibilities for sovereign identity and political community arising in the West, which possibilities worked hand in glove with the colonial enterprise.117 Natural law was fundamental to the notorious standards of civilization, which legitimized the violence of colonial expansion and the maintenance of colonial powers.118 Major publicists like James Lorimer and John Westlake, among others, relied on conflated naturalist and natural law arguments as a prop and apology for colonialism and a system of European privileges under international law.119 Anghie’s chapter in this volume, reflecting his seminal work, makes clear the connection between international law, from the Salamanca School forward, with the subjugation and exploitation of vast regions of the world by Western powers.120 The chapters by Özsu and Ruskola in this volume explore the imperial project sanctioned by international law in the areas of the so-called semi-periphery, including the Ottoman Empire and China.121 Luis Eslava and Sundhya Pahuja, reflecting TWAIL (Third World Approaches to International Law) scholarship and advocacy, though not addressing natural law in particular, have explored the complex and coercive role played by universalist international law in global sites of disempowerment over time.122 Once the historiographical treatment is allowed, once natural law is understood in a contiguous relationship with the development (p. 298) of international law as a whole through the centuries, then it is complicit also in those practices of disempowerment. That disempowerment has facilitated both extreme material inequality in the world today, and ongoing threats to indigenous identities.123 Likewise, a variety of work grouped under the title of feminist theory explores, among other things, the manifold ways that a combination of naturalism and universalism in international law serves to disempower women in a variety of contexts, including the creation and perpetuation of unequal status across the world,124 and the construction and maintenance of gender stereotypes with disparate but consistently damaging effects.125 Finally, mainstream recognition of imperial projects pursued under international law by the US since the 2003 Iraq War have focused on various and blended appeals to rationalism, naturalism, and justice.126 All of the foregoing studies have contributed to an evolving understanding of emergent patterns of global governance, the latest legacy of the linear presentation, tied to familiar, expansive powers.127

Crucial to this linear narrative of natural law underlying a hegemonic enterprise of international law is the development of twin privileges for commutative justice and private property.128 The two together are productive of elements of Enlightenment theory applied to international law, including presumptions in favour of individualism and subjectivity in the international system, and a coordinate suppression of social justice. The logic of self-interest becomes a logic of rationality, giving rise to a functional vocabulary elevated as the sole vocabulary capable of communicating ends in the international environment.129 In brief, roots of dominium in the Salamanca School develop into liberal individualism,130 which serves to promote on universal terms a liberal theory of politics that underlies international law and world relations today.131 The analysis dovetails with depictions of natural law as (p. 299) foundational of the Western colonial project, and, with it, the deep structure of modern international law.132 International law thereby underwrites the power of individual persons over objects and other people, and consolidates that power in select offices by means of vocabularies of universality and instrumentalism.

The linear narrative describes the successful advance of a hegemonic enterprise in international law and relations, founded in and informed by natural law doctrine. Consequently, it describes natural law in a way that is static, revealing a consistent thread though different periods in the elevation of the individual, the affirmation of the subjective, a compromised moral vocabulary, and a compromised pretension to telos. Those factors conduce to a system of law that employs a functional vocabulary, by which particular ends are assimilated into a pretension to universality. Appreciating this historical continuity is crucial to appreciating the consequences of aspects of natural law doctrine operating in combination with a coordinate series of world-historical developments. Despite that continuity, however, natural law has not been one thing at all times. To define natural law as an undifferentiated whole identical with the compromised character of contemporary international law, and according to identical discontents in all periods, would be anachronistic and misleading. Rather, the linear narrative concerns the development of the empire of the liberal international system. The inquiry into natural law is subordinated to a demonstration of the roots of liberal ideology, and an examination of those aspects that have contributed in consistent fashion to an expansive phenomenon that has been developing at least since the early-modern roots of the international system. But it does not represent a comprehensive examination of natural law doctrine per se.

The dialectical story focuses on the aspects of change, and demonstrates how the doctrine has also served to open up new possibilities for political organization, including emancipatory change, in historical and political contexts. The different conceptions of Vitoria and Pufendorf, by this presentation, contribute to nodal points in the dialectic, and we are today at a point of synthesis, which is not identical with either, but reflects elements of both. As noted, each of the first two stages of natural law in international legal theory involved a different conception of the political. The first period fitted within a political theology reliant on analogy to the body,133 though it reconfigured the appreciation of that body and its guiding consciousness. The second period still more radically reconceived the body politic in terms of contract. Friedrich Kratochwil has appraised the shift as (p. 300) ‘one of the most far reaching conceptual revolutions’.134 Each conception, body, and contract, foregrounded different interests and ambitions, opened up new possibilities, and raised new problems.135 The third, current stage, commenced with the reaction against individualism and the positivist orthodoxy of the eighteenth and nineteenth centuries, turning to the Salamanca School for support, but disfavouring the immutable character of its pretension to universality. As noted, twentieth-century figures sought instead to accommodate classical natural law doctrine with a refined doctrine of legal positivism, a distinct pretension to empirical science, and a basic appreciation of liberal autonomy, as well as the fundamental authority accorded to sovereign states. In light of these diverse and not wholly complementary epistemic and ontological mandates, a natural body politic was held to be discernible on the basis of a comprehensive and accurate observation of social and political reality, more satisfying than the different epistemological foundations on which antiquated natural law doctrines and the formal system of interstate relations and international law purported to rest. That natural reality was understood in terms of the lived, historical reality of relations in the world.

In consequence, the return to a conception of a unified body politic, in keeping with classical natural law doctrine, has been carried forward in conjunction with twinned appeals to a social nature and historical context. The organization of an organic body politic, and the norms appropriate to it, are apprehended in terms of specific, historical acts and practices—the sum of particular exercises of universal (and universally-bounded) aptitudes or inclinations, in combination with changing material conditions. A basic unity underlying a contingent vocabulary emerges, one that is consistently expressive of an immanent condition of interconnectedness, which founds aspirations to a telos for the international system across changing manifestations in material contexts. To return for a moment to Kant, the contemporary position approximates his posture with respect to moral theory. To paraphrase: the basic unity—or the moral good—is not hard to appreciate, but its systemic expression will be complex.136

Also in keeping with a Kantian theme, the legacy of natural law today suggests a complex account of both autonomy and ends. That legacy can be discerned in diverse work, some of it relatively far from the familiar natural law vocabularies. Recent theoretical works in international law join visions of its future to appeals to some common, constitutive capacities for communication and choice,137 (p. 301) others to an appreciation of otherwise inchoate global or transnational publics, and emergent global or transnational public goods, reflecting a sense of an ineluctable political phenomenon, as well as some understanding of moral or material ends appropriate to it.138 These current lines of thought—together with the myriad schools associated variously with social constructivism, process theory, and interactional theory, as touched on earlier—suggest new ways of conceptualizing political organization under changing historical circumstances, establishing new but naturally-occurring grounds for political organization, tied to an appreciation of human nature. Each aims to merge the unity of the Spanish School with the autonomy of the Enlightenment liberals, while each, properly conceived, aims to defy controlling forms of organization otherwise definitive of international and world relations. And each takes further the idea of an organic body politic arising naturally out of individual acts of agency globally.

Notably—if for understandable reasons—a figurative head is once again missing from the foregoing presentations of a renewed, organic body. Whereas the Salamanca School entertained the idea of a social consciousness, however, and Dante even posited the collective mind, the contemporary scholars treated here largely eschew such apparently mystical speculations. But for the same reasons, contemporary theorists must contend with the recent critique raised in the context of managerialism and expertise: the system of international law, so the critique goes, suffers from a failure of normativity, an absence of any guiding consciousness or conscience.139 At the same time, it bears noting that this absence works together with the post-modern mandate: to cut off the head of the king.140 In the light of these conflicting pressures, then, I turn at last to an example of recent developments, pointing to possibilities for further inquiry suggestive of ongoing changes in the dialectics of natural law within the international legal theory.

I turn for the purpose to the recent dialogue of sorts between Janne Nijman and Anthony Carty. They each expressly explore a new interpretation of natural law as a counter-hegemonic program. But in doing so, they also confront post-modern theory that has advanced alongside a critique of hegemony. Their confrontations with post-modern theory suggest a still-changing image of mind and body at work in the natural law dialectic. Post-modern theory, as noted, would decapitate the constructed body politic, thereby denying the modern pretension to channel a universal consciousness via the constructed heads of sovereign states represented by (p. 302) governments.141 But there arguably remains, once the construction is beheaded, to provide for ‘a philosophy that would enable man to re-establish a sense of wholeness by determining or finding “meaning”’.142

Rather than behead the king, Nijman and Carty explore a means to redeem the subject. They adopt aspects of post-modern critique, but reject some related conclusions.143 To this end, they propose alternatives to a vocabulary still limited to terms propounded by Hobbes, making clear their projects fall within a distinct natural law idiom.144 Nijman provides that her theory may ‘be placed in a natural law tradition’, though ‘contrary to premodern and modern perspectives it does not conceive of natural law as a set of divine or universalistic dictates’.145 Carty affirms that ‘the inspiration of the ius natural is that we return to recognize the other as similar, as reflections of the self, images of the self to be found in others because we have a common origin’.146

Thus both have turned to natural law to redeem the subject from liberal subjectivity, as well as from the opposed and unsparing critical deconstruction of the subject. For Nijman, this means reconceiving legal personality in such a way as to ground a renewed system of international law oriented towards distributive justice and an affirmation of plurality.147 For Carty, it means not only defying the imposition of a particularistic language on others, in the guise of universality,148 but also an escape for international law from ‘the prison house of language’149 reflecting the synchronic nature of modern international legal structures.150 That synchronic nature corresponds, not coincidentally, with the turn to commutative (as opposed to distributive) justice observed by Koskenniemi—commutative justice reflecting the privileging of an individualism in which the individual is constantly reduced to a counterweight, an abstraction without any personal integrity, a universalized unit existing outside of time and outside of history.151 To redress this, a substantial appreciation of historical context is critical, but not one that lapses into sheer (p. 303) relativism.152 For the purpose, Nijman and Carty each turn to a Hegelian natural law argument, founded in principles of alterity, and adapted by way of Paul Ricoeur’s sense of history and hermeneutics.153 In short, the ‘historical-political community’ arises out of a struggle for recognition, productive of an ethos of mutual recognition, as opposed to a struggle for survival, with its ethos of self-preservation.154 This produces a body that figuratively appears capable of vision.155 And this new body politic is proposed in opposition to the body always engaged in an internecine struggle for survival, which admitted only an ethos of self-preservation and self-interest.

Following the Hobbesian theory of knowledge, founded in contract, the individual is comprehended in terms of interests and alienation, which conduces to the paranoid condition of international relations and consequent perversions of international law.156 Nijman and Carty, by contrast, explore the possibility of a theory of international law founded in a vocabulary of alterity, and a political community unified by a definitional association of self and other. Instead of an order that oscillates between fear and security,157 established according to mutual acts of alienation, they contemplate an order that oscillates between strangeness and respect, established according to mutual acts of recognition. In oscillating between strangeness and respect, of course, there remains the possibility for great mischief. That is a facet of a dialectical presentation: a constant oscillation, each shift triggered by developments associated with the last.158


In closing, two points about why we keep returning to the natural law idiom in international law. First, both the hegemonic and the dialectical presentations (p. 304) suggest the possibility that international law has never entirely left the broad confines of the natural law paradigm. The diminution of natural law in practice had to do with the reconfiguration of natural law according to the premises of Enlightenment liberalism. That reconfiguration, which reduced the natural law to a platform for the subjective expression of will, served to open new space for political organization by means of the same theoretical construction that continues to define the liberal hegemonic project. Today, there are new configurations that have been developing for nearly a century, which exhibit aspects drawn from each of the prior two major periods; there also already exist possibilities for new inquiries which appear capable of going farther still. The new configurations are all bound up with the perceived entropy of old conceptions and constructions of political organization, and perceptions of a changed global political context.

Secondly, Koskenniemi has suggested that natural law is historically attractive in times of transformation or crisis, when ‘basic aspects of the world are questioned’.159 This would be true for any number of legal systems, where recourse to some ready-made but independent set of legal values offers an escape of sorts from intolerable legal relations under positive law or other regimes. But there is an especial appeal for international law. Natural law—not unlike voluntarist positive law, but differently—presupposes or reflects the community to which it applies and the order which it sustains. At the same time, the international community is a historically unstable construction.160 Moreover, an international public realm comprehended as an area of competition among state interests, defined wholly in terms of diplomatic practices, has long seemed insufficient. Philip Allott refers to this condition as a pathological ‘unsociety’.161 And the unsociety of sovereign states has been under increasing pressure, socially and politically, since its apex in the nineteenth century, most recently as a function of so-called globalization, and the multiplication of transnational interactions of all sorts. There exists a perceived need for a more thorough and adequate expression under law of political and social interconnectedness in the world and across international boundaries. In this vein, the vocabulary of natural law suggests one means of giving voice to a basis for common, normative relations that go beyond the tenuous and highly mediated relations for which international law, for the most part, currently provides. On that note, however, it bears restating: natural law offers this potential only on the basis of pre-figured community—or, still more precisely, on the basis of pre-figured commonality and pre-determined community. Natural law opens up a new future by constraining it from the outset. For that reason, it cannot offer a full or satisfactory solution to the problems it addresses. Likewise, for that reason, natural (p. 305) law is rarely invoked any more with great enthusiasm; more often it is minimized, acknowledged but hardly celebrated. In short, what role it may have is limited. As has been seen, the constraints of natural law—to the extent that they are exploited in any given historical context—inevitably become part of the problem under the changing conditions upon which they work, prompting again and again a return to the dialectic.

Thus natural law retains its relevance for international legal theory today, as one framework by which to comprehend or imagine changing possibilities and norms for a political organization in an international and a world community. But it retains its relevance in both of the two senses charted here, dialectical and hegemonic. The former demonstrates the ongoing capacity of natural law doctrine to articulate alternative normative programs, including programs for changing forms of political organization. The latter helps to train a light on persistent hegemonic aspects of international law as they arise within the vocabulary of new normative programs going forward. In sum, natural law remains a carrier for ideas of new political possibility, even as it must confront the hegemonic character of international law as it has developed and may develop, in part, out of iterations of natural law possibilities.


1  See I Hunter, ‘Natural Law as Political Philosophy’ in DM Clarke and C Wilson (eds), The Oxford Handbook of Philosophy in Early Modern Europe (OUP Oxford 2011) 475–99.

2  Cf P Capps, ‘International Legal Positivism and Modern Natural Law’ in J d’Aspremont and J Kammerhofer (eds), International Legal Positivism in a Post-Modern World (CUP Cambridge 2014) 213–40; P Capps, ‘Natural Law and the Law of Nations’ in A Orakhelashvili (ed), Research Handbook on the Theory and History of International Law (Edward Elgar Cheltenham 2011) 61–92.

3  See eg M Shaw, International Law (6th edn CUP Cambridge 2008) at 53–4.

4  A notable exception is the jurisprudence of Judge Cançado Trindade: see eg Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v Russian Federation) (Preliminary Objections) [2011] ICJ Rep 70, at 322 (Judge Cançado Trindade, Dissenting Opinion).

5  M Koskenniemi, ‘Miserable Comforters: International Relations as New Natural Law’ (2009) 15 European Journal of International Relations 395–422, at 403. For the possibility that natural law survived after all, but in a transformed state, see further M Koskenniemi, ‘Transformations of Natural Law: Germany 1648–1815’ in this Handbook.

6  See eg I de la Rasilla del Moral, ‘Francisco de Vitoria’s Unexpected Transformations and Reinterpretations for International Law’ (2013) 32 International Community Law Review 287–318; A Orford, ‘The Past as Law or History? The Relevance of Imperialism for Modern International Law’ (Institute for International Law and Justice, New York University Law School, International Law and Justice Working Paper No 2012/2), subsequently published in M Toufayan, E Tourme-Jouannet, and H Ruiz Fabri (eds), International Law and New Approaches to the Third World (Société de Législation Comparée Paris 2013) 97–118; M Koskenniemi, ‘Empire and International Law: The Real Spanish Contribution’ (2011) 61 University of Toronto Law Journal 1–36; ‘Miserable Comforters’ (n 5); A Anghie, Imperialism, Sovereignty and the Making of International Law (CUP Cambridge 2005); R Lesaffer, ‘The Grotian Tradition Revisited: Change and Continuity in the History of International Law’ (2002) 73 British Year Book of International Law 103–39; W Grewe, The Epochs of International Law (M Byers trans and rev) (de Gruyter Berlin 2000 [1984]); D Kennedy, ‘Primitive Legal Scholarship’ (1986) 27 Harvard Journal of International Law 1–98. For a related inquiry focused on the hegemonic term, rather than the historiographical, see M Koskenniemi, ‘International Law and Hegemony: A Reconfiguration’ (2004) 17 Cambridge Review of International Affairs 197–218.

7  Cf I Hunter, ‘The Recovery of Natural Law: Hochstrasser’s History of Morality’ (2001) 30 Economy and Society 354–67, at 355.

8  Cf M Koskenniemi, ‘Law, Teleology and International Relations: An Essay in Counterdisciplinarity’ (2011) 26 International Relations 3–34; N Krisch, ‘International Law in Times of Hegemony: Unequal Power and the Shaping of the International Legal Order’ (2005) 16 European Journal of International Law 369–408.

9  U Özsu, ‘The Question of Form: Methodological Notes on Dialectics and International Law’ (2010) 23 Leiden Journal of International Law 687–707, at 698.

10  L Gross, ‘The Peace of Westphalia, 1648–1948’ (1948) 42 American Journal of International Law 20–41.

11  M Janis, ‘Jeremy Bentham and the Fashioning of “International Law”’ (1984) 78 American Journal of International Law 405–18.

12  The temporal division—neo-scholastics through Grotius, a new period commencing with Hobbes—approximates the schema employed by Richard Tuck in his seminal work, Natural Rights Theories, but it bears noting that the nature of the inquiry is not the same, and neither are the conclusions drawn. See R Tuck, Natural Rights Theories: Their Origin and Development (CUP Cambridge 1979).

13  Cf A Orford, ‘Jurisdiction without Territory: From the Holy Roman Empire to the Responsibility to Protect’ (2009) 30 Michigan Journal of International Law 981–1015, at 984–9; AH Snow, ‘The Law of Nations’ (1912) 6 American Journal of International Law 890–900, at 890–2.

14  ‘The Grotian Tradition Revisited’ (n 6) 121–5.

15  F de Vitoria, ‘De Indis Noviter Inventis’ (J Pawley Bate trans) in JB Scott, The Spanish Origin of International Law: Francisco de Vitoria and His Law of Nations (Clarendon Press Oxford 1932 [1532]) appendix A, i–xlvi, at xxxviii.

16  F de Vitoria, ‘De Potestate Civili’ (GL Williams trans) in The Spanish Origin of International Law (n 15) appendix C, lxxi–xci, at lxxiv–lxxv.

17  ‘De Indis Noviter Inventis’ (n 15) xxxviii.

18  Ibid.

19  ‘De Indis Noviter Inventis’ (n 15) xxxviii.

20  F de Vitoria, ‘De Jure Belli’ (J Pawley Bate trans) in The Spanish Origin of International Law (n 15) appendix B, xlvii–lxx, at lvi.

21  ‘De Potestate Civili’ (n 16) xc.

22  ‘The Grotian Tradition Revisited’ (n 6) 125–6.

23  F Suárez, A Treatise on Laws and God the Lawgiver in Selections from Three Works of Francisco Suárez, SJ (GL Williams et al., trans) (Clarendon Press Oxford 1944) vol 2, 3–646, at 348.

24  Ibid 348–9.

25  Ibid 459.

26  The Spanish Origin of International Law (n 15) 3.

27  See also MJ van Ittersum, ‘Hugo Grotius (1583–1645): The Making of a Founding Father of International Law’ in this Handbook. For still another influential account, see H Bull, B Kingsbury, and A Roberts (eds), Hugo Grotius and International Relations (OUP Oxford 1992).

28  H Grotius, Mare Liberum (JB Scott ed R van Deman Magoffin trans) (Clarendon Press Oxford 1916 [1609]) chs 1, 5, 12.

29  H Grotius, De Jure Belli ac Pacis Libri Tres (FW Kelsey trans) (Clarendon Press Oxford 1925 [1625]) Prolegomena, at [23]–[24].

30  Ibid [7]‌–[8].

31  Ibid bk II, ch xxv, § viii, para 2.

32  F de Vitoria, ‘On the American Indians’, in A Pagden and J Lawrance (eds), Vitoria, Political Writings (CUP Cambridge 1991) 231–92, at 252–4ff.

33  Imperialism, Sovereignty and the Making of International Law (n 6) 13–31.

34  ‘Empire and International Law: The Real Spanish Contribution’ (n 6) 15ff.

35  P Zapatero, ‘Legal Imagination in Vitoria: The Power of Ideas’ (2009) 11 Journal of the History of International Law 221–71.

36  ‘De Potestate Civili’ (n 16) lxxiv–lxxv.

37  D Alighieri, Monarchy (P Shaw trans) (CUP Cambridge 1996 [c 1312–13]). For further discussion of Dante’s collective mind in a related context, see J Bartelson, Visions of World Community (CUP Cambridge 2009) at 48–60.

38  ‘De Potestate Civili’ (n 16) lxxv–lxxvii.

39  See generally ‘Legal Imagination in Vitoria’ (n 35).

40  Cf ‘Natural Law as Political Philosophy’ (n 1); J Israel, Enlightenment Contested: Philosophy, Modernity and the Emancipation of Man (OUP Oxford 2006).

41  Cf  I Hunter, ‘The Figure of Man and the Territorialisation of Justice in “Enlightenment” Natural Law: Pufendorf and Vattel’ (2013) 23 Intellectual History Review 289–307; Imperialism, Sovereignty and the Making of International Law (n 6).

42  Cf J Israel, Radical Enlightenment: Philosophy and the Making of Modernity 1650–1750 (OUP Oxford 2002).

43  See eg I Hunter, Rival Enlightenments: Civil and Metaphysical Philosophy in Early Modern Germany (CUP Cambridge 2006).

44  The work of the classical figures canvassed here has given rise to many, sometimes conflicting interpretations and schools of thought. I present here a plausible account, but one that can only be very partial and very condensed. Cf W Werner and G Gordon, ‘Kant, Cosmopolitanism, and International Law’ in this Handbook. For still other accounts, see J d’Aspremont, ‘The Foundations of the International Legal Order’ (2007) 18 Finnish Yearbook of International Law 219–56, at 225–6; R Tuck, ‘Hobbes’ Moral Philosophy’ in T Sorrell (ed), The Cambridge Companion to Hobbes (CUP Cambridge 1996) 175–207, at 190–1.

45  Cf A Pagden, ‘Human Rights, Natural Rights, and Europe’s Imperial Legacy’ (2003) 31 Political Theory 171–99, at 180.

46  I Kant, ‘Perpetual Peace: A Philosophical Sketch’ in Kant: Political Writings (H Reiss ed HB Nisbet trans) (2nd edn CUP Cambridge 1991 [1795]) 93–130.

47  R Tuck, ‘Hobbes and Democracy’ in A Brett and J Tully (eds), Rethinking the Foundations of Modern Political Thought (CUP Cambridge 2006) 171–90.

48  T Hobbes, Leviathan (CB Macpherson ed) (Penguin Classics New York 1985 [1651]) at 223–8.

49  Ibid 190ff.

50  Ibid 223–39.

51  Cf Q Skinner, ‘The State’ in T Ball, J Farr, and R Hanson (eds), Political Innovation and Conceptual Change (CUP Cambridge 1989) 90–131.

52  Cf Q Skinner, ‘The Sovereign State: A Genealogy’ in H Kalmo and Q Skinner (eds), Sovereignty in Fragments: The Past, Present and Future of a Contested Concept (CUP Cambridge 1979) 26–46, at 34–8.

53  Cf Q Skinner, ‘The Ideological Context of Hobbes’ Political Thought’ (1966) 9 Historical Journal 286–317.

54  For a salient statement of differences, see ‘Miserable Comforters’ (n 5). On Kant, cosmopolitanism, and international law more generally, see also W Werner and G Gordon, ‘Kant, Cosmopolitanism, and International Law’ in this Handbook.

55  I Kant, ‘Idea for a Universal History with a Cosmopolitan Purpose’ in Kant: Political Writings (n 46) 41–53, at 47–9.

56  Ibid 45–6.

57  ibid 44–5.

58  Ibid 51–3.

59  Ibid 50–1.

60  Ibid.

61  ‘Perpetual Peace’ (n 46) 114.

62  See generally ‘The Figure of Man and the Territorialisation of Justice in “Enlightenment” Natural Law’ (n 41). As Hunter demonstrates, Pufendorf and Vattel had separate agendas, but they were ultimately complementary in elevating the subjective individualism at the core of Hobbes’ theory.

63  Kant simultaneously laments and affirms this in the same passage in which he refers to Hobbes, Pufendorf, and Vattel as sorry comforters, bitterly holding that ‘[t]‌he way in which states seek their rights can only be by war, since there is no external tribunal to put their claims to trial. … [and] peace can neither be inaugurated nor secured without a general agreement between the nations’: ‘Perpetual Peace’ (n 46) 103–4.

64  S Pufendorf, Of the Law of Nature and Nations: Eight Books (B Kennett trans) (S Aris London 1729 [1672]) bk V, ch 13, §2.

65  Ibid bk I. See also ‘Miserable Comforters’ (n 5) 401; S Hall, ‘The Persistent Spectre: Natural Law, International Order and the Limits of Legal Positivism’ (2001) 12 European Journal of International Law 269–307, at 275.

66  ‘The Persistent Spectre’ (n 65) 274.

67  E de Vattel, The Law of Nations, or, Principles of the Law of Nature, Applied to the Conduct and Affairs of Nations and Sovereigns (GG and J Robinson London 1797 [1758]) Preliminaries, § 28.

68  Cf JL Brierly, The Law of Nations: An Introduction to the International Law of Peace (OUP Oxford 1963) at 37.

69  Cf G Cavaller, ‘Vitoria, Grotius, Pufendorf, Wolff, and Vattel: Accomplices of European Colonialism and Exploitation or True Cosmopolitans?’ (2008) 10 Journal of the History of International Law 181–209.

70  See eg ‘De Potestate Civili’ (n 16) lxxiii.

71  Cf ‘Hobbes and Democracy’ (n 47) 171. This equality, it bears emphasizing, was largely limited to the states of Europe by virtue of the notorious ‘standards of civilization’—the standard itself associated with conflated naturalist and natural law speculation—thereby facilitating subjugation of the non-European world. See B Bowden, ‘The Colonial Origins of International Law: European Expansion and the Classical Standard of Civilization’ (2005) 7 Journal of the History of International Law 1–24.

72  The Law of Nations (n 67) Preliminaries, § 18, largely repeated at bk IV, ch 6, § 78.

73  See E Nys, Les origines du droit international (Alfred Castaigne Bruxelles and Thorin & Fils Paris 1894); C Barcia Trelles, ‘Fernando Vazquez de Menchaca (1512–1569): L’école espagnole du Droit international du XVIe siècle’ (1939) 67 Receuil des Cours 430–534; C Barcia Trelles, ‘Francisco Suarez (1548–1617) (Les théologiens espagnols du XVIe siècle et l’école moderne du Droit international)’ (1933) 43 Receuil des Cours 385–553; C Barcia Trelles, ‘Francisco de Vitoria et l’École moderne du Droit international’ (1927) 17 Receuil des Cours 109–342; The Spanish Origin of International Law (n 15).

74  See eg A Snow, ‘International Law and Political Science’ (1913) 7 American Journal of International Law 315–28. That sense has lately been contextualized according to the legacy of competing colonial ambitions in the West. See eg M Koskenniemi, ‘Colonization of the “Indies”: The Origin of International Law?’ in Y Gamarra (ed), La idea de la América en el pensamiento ius internacionalista del siglo XXI (Institución Fernando el Católico Zaragoza 2010) 43–63; cf A Pagden, ‘The Genesis of “Governance” and Enlightenment Conceptions of the Cosmopolitan World Order’ (1998) 50 International Social Science Journal 7–15. A non-exhaustive list of other relevant factors includes advancing industrialization and the advance of capitalism on other fronts, as well as ascendant forms of democratic governance, together with the rise of global revolutionary politics. Cf E Hobsbawm, The Age of Empire: 1875–1914 (Weidenfeld and Nicholson London 1987).

75  H Lauterpacht, ‘Kelsen’s Pure Science of Law (1933)’ in E Lauterpacht (ed), International Law, Being the Collected Papers of Hersch Lauterpacht (CUP Cambridge 1975) vol 2, 404–30.

76  Concerning the roots of that split, see ‘The Figure of Man and the Territorialisation of Justice in “Enlightenment” Natural Law’ (n 41) 296.

77  ‘The Persistent Spectre’ (n 65) 269–73.

78  H Lauterpacht, The Function of Law in the International Community (reissue OUP Oxford 2011 [1933]) at 429–30.

79  I Scobbie, ‘The Theorist as Judge: Hersch Lauterpacht’s Concept of the International Judicial Function’ (1997) 8 European Journal of International Law 264–98, at 266. Josef Kunz also observed the embrace of natural law elements in Lauterpacht’s work: JL Kunz, ‘Natural Law Thinking in the Modern Science of International Law’ (1961) 55 American Journal of International Law 951–8, at 955.

80  H Lauterpacht, ‘Spinoza and International Law’ (1927) 8 British Year Book International Law 89–107, at 91.

81  H Lauterpacht, ‘The Grotian Tradition in International Law’ (1946) 23 British Year Book of International Law 1–53, at 17.

82  Ibid 43.

83  H Lauterpacht, ‘The Absence of an International Legislature and the Compulsory Jurisdiction of International Tribunals’ (1930) 11 British Year Book of International Law 134–57, at 151.

84  ‘The Grotian Tradition’ (n 81) 51.

85  Ibid 24.

86  A Carty, ‘Alfred Verdross and Othmar Spann: German Romantic Nationalism, National Socialism and International Law’ (1995) 6 European Journal of International Law 78–97, at 94.

87  Ibid 87.

88  Ibid 88.

89  A Verdross, ‘Two Arguments for an Empirical Foundation of Natural-Law Norms: An Examination of Johannes Messner’s and Victor Kraft’s Approaches’ (1975) 3 Syracuse Journal of International Law and Commerce 151–8, at 151.

90  Ibid 158.

91  Ibid 153.

92  Ibid 155–6.

93  P Kooijmans, The Doctrine of the Legal Equality of States: An Inquiry into the Foundations of International Law (AW Sythoff Leyden 1964) at 192–3.

94  Others included Wilfried Schaumann, Ernst Sauer, Friedrich Buchholz, Josef Felder, and Friedrich von der Heydte: ibid at 215–38. For a still more comprehensive list of mid-century jurists arguably adopting aspects of natural law jurisprudence, see ‘Natural Law Thinking in the Modern Science of International Law’ (n 79) 951.

95  The Doctrine of the Legal Equality of States (n 93) 215.

96  The Doctrine of the Legal Equality of States (n 93) 192–247.

97  Ibid 215.

98  Ibid. The phrase has also been attributed to Rudolf Stammler, an influential neo-Kantian jurist in Germany at the turn of the twentieth century: see R Stammler, Die Lehre von dem Richtigen Rechte (J Guttentag Berlin 1902).

99  International Status of South-West Africa (Advisory Opinion) [1950] ICJ Rep 128, at 175 (Judge Álvarez, Dissenting Opinion), 479.

100  See eg ibid 177.

101  See G Gordon, ‘Innate Cosmopolitan Dialectics at the ICJ: Changing Perceptions of International Community, the Role of the Court, and the Legacy of Judge Álvarez’ (2014) 27 Leiden Journal of International Law 309–30.

102  A Becker Lorca, ‘Universal International Law: Nineteenth-Century Histories of Imposition and Appropriation’ (2010) 51 Harvard International Law Journal 475–552, at 547. It must be noted, however, that Becker Lorca focuses on jurists adopting positivist doctrines of the nineteenth century. Moreover, Becker Lorca demonstrates that nineteenth-century non-European jurists on the whole tended towards positivist doctrine and away from natural law and naturalism. He offers the following explanation, at 489 (citations omitted):

the natural law remnants that carried on to the mid-nineteenth century were particularly detrimental to the interests of non-European nations. . . . Non-European international lawyers therefore welcomed positivism’s break with the naturalist tradition, for positivism confined law to the rules emanating from sovereign will while displacing detrimental rules deduced from general naturalist principles. . . . For example, only the first attempts to assimilate international law at the beginning of the nineteenth century in China and Japan depended on drawing parallels between international law as natural law and Confucianism. As soon as professional international lawyers took over the legal aspects of the interaction with Western powers, latter generations of Chinese or Japanese intellectuals opted for positivism.

104  M McDougal, WM Reisman, and A Willard, ‘The World Community: A Planetary Social Process’ (1987) 21 UC Davis Law Review 807–972, at 808–9.

105  Ibid 808.

106  Ibid 812.

107  Cf H Koh, ‘Why Do Nations Obey International Law?’ (1997) 106 Yale Law Journal 2599–662.

108  Cf A Wendt, Social Theory of International Politics (CUP Cambridge 1999).

109  Though these theories carry forward the adaptation of natural law peculiar to international law in the twentieth century, they also cut against the most prominent reformulation of natural law in twentieth-century legal philosophy. That reformulation, a primarily Catholic, neo-Thomist account under the banner of so-called ‘new natural law’ by figures such as John Finnis and Germain Grisez, ties natural law to practical reasoning, with the express intent to avoid recourse to assertions of what is to determine what ought to be: see J Finnis, Natural Law and Natural Rights (Clarendon Press Oxford 1980); G Grisez, ‘The First Principle of Practical Reason: A Commentary on the Summa Theologiae, 1–2, Question 94, Article 2’ (1965) 10 Natural Law Forum 168–201. This line of thinking has, by comparison with its own successes in general fields of theoretical inquiry not specifically addressed to international law, found relatively limited purchase in international legal theory. But it has contributed to scholarship questioning the capacity of liberal or pluralist conceptions of international law to operate in a perfectly neutral register. See eg RP George, In Defense of Natural Law (Clarendon Press Oxford 1999) cf ‘The Recovery of Natural Law’ (n 7) 355.

110  J Brunnée and S Toope, Legitimacy and Legality in International Law: An Interactional Account (OUP Oxford 2010).

111  Ibid 29.

112  Ibid 20–55.

113  J Brunnée and S Toope, ‘International Law and Constructivism: Elements of an Interactional Theory of International Law’ (2001) 39 Columbia Journal of Transnational Law 19–74, at 71.

114  ‘Colonization of the “Indies”’ (n 74); ‘Empire and International Law’ (n 6); Imperialism, Sovereignty and the Making of International Law (n 6); C Miéville, Between Equal Rights: A Marxist Theory of International Law (Brill Leiden 2005). See also ‘The Colonial Origins of International Law’ (n 71) 1; B Buchan, ‘The Empire of Political Thought: Civilization, Savagery and Perceptions of Indigenous Government’ (2005) 18(2) History of the Human Sciences 1–22; RA Williams Jr, The American Indian in Western Legal Thought: The Discourses of Conquest (OUP New York 1990).

115  ‘Miserable Comforters’ (n 5).

116  ‘Empire and International Law’ (n 6).

117  ‘Human Rights, Natural Rights, and Europe’s Imperial Legacy’ (n 45) 180.

118  ‘The Colonial Origins of International Law’ (n 71) 1.

119  See eg J Lorimer, The Institutes of Law: A Treatise of the Principles of Jurisprudence as Determined by Nature (2 vols W Blackwood and Sons Edinburgh 1880); J Westlake, ‘The Principles of International Law’ in The Collected Papers of John Westlake on Public International Law (L Oppenheim ed) (CUP Cambridge 1914) 78–85, at 78–82.

120  A Anghie, ‘Imperialism and International Legal Theory’ in this Handbook; Imperialism, Sovereignty and the Making of International Law (n 6); A Anghie, ‘The Evolution of International Law: Colonial and Postcolonial Realities’ (2006) 27 Third World Quarterly 739–53.

122  L Eslava and S Pahuja, ‘Between Resistance and Reform: TWAIL and the Universality of International Law’ (2011) 3 Trade, Law and Development 103–30, at 105.

123  Cf ‘The Empire of Political Thought’ (n 114) 1.

124  See eg H Charlesworth, C Chinkin, and S Wright, ‘Feminist Approaches to International Law’ (1991) 85 American Journal of International Law 613–45. See also D Otto, ‘Feminist Approaches to International Law’ in this Handbook.

125  A Orford, ‘Feminism, Imperialism and the Mission of International Law’ (2002) 71 Nordic Journal of International Law 275–96.

126  See eg ‘International Law in Times of Hegemony’ (n 8) 393; A Paulus, ‘The War against Iraq and the Future of International Law: Hegemony or Pluralism?’ (2004) 25 Michigan Journal of International Law 691–734.

127  See eg A Anghie, ‘Civilization and Commerce: The Concept of Governance in Historical Perspective’ (2000) 45 Villanova Law Review 887–912, at 891; M Koskenniemi, ‘The Fate of Public International Law: Between Technique and Politics’ (2007) 70 Modern Law Review 1–30.

128  ‘Empire and International Law’ (n 6); Imperialism, Sovereignty and the Making of International Law (n 6).

129  ‘Miserable Comforters’ (n 5).

130  ‘Empire and International Law’ (n 6); ‘Colonization of the “Indies”’ (n 74).

131  The liberal theory of politics is a theory ‘which identifies itself on two assumptions. First, it assumes that legal standards emerge from the legal subjects themselves. … Second, it assumes that once created, social order will become binding on these same individuals.’: M Koskenniemi, From Apology to Utopia: The Structure of International Legal Argument (reissue CUP Cambridge 2006) at 21 (emphasis in original). As presented throughout that work, and on the basis of these two fundamental assumptions, the liberal theory of politics simultaneously underwrites and obscures particular exercises of social and political control.

132  Imperialism, Sovereignty and the Making of International Law (n 6).

133  Cf E Kantorowicz, The King’s Two Bodies: A Study in Mediaeval Political Theology (Princeton University Press Princeton 1957).

134  F Kratochwil, ‘Reflections on Theory and Practice’ (2003) (European University Institute Working Paper, SPS No 2003/16) at 4.

135  Ibid.

136  See I Kant, Fundamental Principles of the Metaphysics of Morals (TK Abbott trans) (Prometheus Amherst 1987 [1785]) at 29–31, § 1.

137  See eg N Onuf, ‘The Constitution of International Society’ (1994) 5 European Journal of International Law 1–19, at 4, 10–13, 18–19.

138  See eg N Krisch, ‘The Decay of Consent: International Law in an Age of Global Public Goods’ (2014) 108 American Journal of International Law 1–40. Thomas Franck’s community of rules is also applicable here: TM Franck, The Power of Legitimacy among Nations (OUP Oxford 1990).

139  ‘The Fate of Public International Law’ (n 127); D Kennedy, ‘Challenging Expert Rule: The Politics of Global Governance’ (2005) 27 Sydney Law Review 5–28.

140  M Foucault, ‘Truth and Power’ in Power/Knowledge: Selected Interviews and Other Writings, 1972–1977 (Harvester Press Brighton 1980) 109–33, at 121.

141  JE Nijman, ‘Paul Ricoeur and International Law: Beyond “The End of the Subject”. Towards a Reconceptualization of International Legal Personality’ (2007) 20 Leiden Journal of International Law 25–64, at 36–7.

142  Ibid 38.

143  To borrow the helpful medical analogy used by Florian Hoffmann, they adopt the same diagnosis, but pursue a new remedy: FF Hoffmann, ‘Gentle Civilizer Decayed? Moving (Beyond) International Law’ (2009) 72 Modern Law Review 1016–34.

144  A Carty, ‘New Philosophical Foundations for International Law: From an Order of Fear to One of Respect’ (2006) 19 Cambridge Review of International Affairs 311–30, at 312.

145  ‘Paul Ricoeur and International Law’ (n 141) 33.

146  ‘New Philosophical Foundations’ (n 144) 312.

147  JE Nijman, The Concept of International Legal Personality: An Inquiry into the History and Theory of International Law (TMC Asser Press The Hague 2004).

148  A Carty, ‘International Legal Personality and the End of the Subject: Natural Law and Phenomenological Responses to New Approaches to International Law’ (2005) 6 Melbourne Journal of International Law 534–52, at 545.

149  Ibid 548.

150  Cf D Kennedy, International Legal Structures (Nomos Baden-Baden 1987).

151  ‘International Legal Personality and the End of the Subject’ (n 148) 547ff.

152  ‘International Legal Personality and the End of the Subject’ (n 148) 536.

153  ‘Paul Ricoeur and International Law’ (n 141) 33 and 63.

154  Ibid 61–3; ‘International Legal Personality and the End of the Subject’ (n 148) 552.

155  But Florian Hoffmann offers a tantalizing wrinkle on the vision of Carty’s natural law, and Nijman’s by extension. Relying on Arendt, he proposes to understand mutual recognition as occurring in a radically restricted temporal space: ‘In this space between the us and the (O)ther, human agency is concentrated in the present.’: ‘Gentle Civilizer Decayed?’ (n 143) 1033. The result is ‘a revolutionary moment that unfolds in the short space after one and before another law, when humans are radically thrown back to their own communal responsibility and when they have to found authority, rather than rely on someone else’s’.: at 1034.

156  Cf P Allott, Eunomia: A New Order for a New World (OUP Oxford 1990) at xii.

157  Cf B Buchan, ‘Liberalism and Fear of Violence’ (2001) 4(3) Critical Review of International Social and Political Philosophy 27–48.

158  And in that light, I wish to emphasize that the purpose of this chapter, considering natural law over time, is not to defend any one definition of natural law.

159  ‘Law, Teleology and International Relations’ (n 8) 13.

160  Cf R-J Dupuy, ‘Communauté internationale et disparités de développement’ (1979) 165 Recueil des Cours 9–231.

161  Eunomia (n 156) 243–8.