Recent decades have seen a series of publications focusing on the cosmopolitan dimension in Kant’s philosophy. Lorena Cebolla Sanahuja continues this scholarly enterprise, yet her own approach distinguishes itself from previous interpretations in three respects. First, there is a clear focus on the role of the individual in cosmopolitan theories. As Sanahuja puts it: ‘The purpose was to inquire into the plausibility of a link . . . that could aid [in interpreting] the history of cosmopolitanism as one [with the individual at its basis], understood as an active citizen of the world on the basis of some attributes that make of him the primary subject and actor of law, and that defines cosmopolitan citizenship as the most basic or fundamental form of citizenship; one that compels the creation of a right adequate to the nature of its subjects’ (p. 8). The second distinctive feature of Sanahuja’s approach is the emphasis on the idea of common property. She argues throughout her book that it is the quality of humans as co-owners of the world that requires the construction of a common comprehensive legal framework (cf. p. 12). Finally, the book takes a decidedly Kantian look at the history of cosmopolitanism.

This story is told from its beginnings in Greek and Roman antiquity, with Sanahuja describing forms of ‘proto-cosmopolitanism’ (chapter 2). According to the author, the prehistory of cosmopolitanism in antiquity has many shortcomings (cf. pp. 38 and 51), as a cosmopolitan perspective ‘regarding the notion of citizenship and citizen of the world’ only emerged at the beginning of the fifteenth century with the period of ‘Second Scholasticism’. This is also the focus of the third chapter: ‘The Rise and Fall of Cosmopolitan Law’. The ‘laws of humanity’ were considered a new field of law and no longer seen as ‘an extension of the private law of an Empire and its faith’ (p. 83). Sanahuja does not fail to note the irony that the theologians of the Second Scholastic period questioned or even rejected theological arguments for (Spanish) colonialism and empire. Instead, they started a process of ‘rationalization of law’, redefining natural law as partially independent of divine will. Consequently, the idea of subjective natural rights was reinforced (see p. 87). Sanahuja correctly criticizes the reductionist interpretations of Martti Koskienniemi and China Tom Miéville, who claim that the thought of the Salamanca School amounts to nothing more than a defence of imperialism and free trade. After comprehensive interpretations of Francisco de Vitoria, Domingo de Soto, Francisco Suárez and Fernando Vázquez de Menchaca, the author claims that these representatives of the Second Scholastic period were in fact close to Kant’s approach. ‘All the elements that are part of the later Kantian notion of cosmopolitanism are present in the thought of these authors’, including ‘[c]ommon property, self-ownership and self-determination, the subject as ultimate source of political and legal authority, the right and duty of hospitality understood as a form of acknowledgment of the guest and visitor, membership in a broader legal community’ (p. 112). For Sanahuja, the achievements of the Second Scholastic period also led – ‘paradoxically’ – to the rise of a new legal theory that favoured legal positivism, the state’s interests and capitalist societies. In her narrative, this was the beginning of the ‘fall’ of cosmopolitan law, as exemplified by the writings of the Italian jurist Alberico Gentili (1552–1608).

The fourth chapter (‘On the Sorry Comforters of the Law of Nations. Toward a “Moralizing” of Cosmopolitanism’) fleshes out this decline of cosmopolitan law up to Kant. It is triggered or caused by processes such as the continued trend towards legal positivism, the secularization of the law of nations, the rise of a ‘cosmopolitan ideology of the market’ (p. 129) and by an emphasis on state sovereignty and state interests. As the title indicates, the author sees a crucial shift from a legal understanding of cosmopolitanism to a merely moral conception. The new natural law theorists who founded ‘the law of nations would lose the cosmopolitan perspective that corresponds to the subjective and universal right of self-determination, understood properly as positive law and closely linked to a subjective right to property’ (p. 127). As the will of the individual citizen was also ‘translated’ into the will of the government, cosmopolitan citizenship was ‘doomed’ (p. 128). The titular ‘sorry comforters’ are of course the leidige Tröster of Kant’s essay Zum ewigen Frieden: Hugo Grotius, Samuel Pufendorf, Emer de Vattel and – in parentheses – Christian Wolff.

Chapter 5 (‘From Cosmopolitanism to the Virtuous Market’) is an analysis of the commercial cosmopolitanism of Enlightenment philosophers such as Montesquieu, Hume and Smith. In their theories, commerce became ‘the ultimate cause, goal and solution to relations between peoples’ (p. 157). Commerce became and ‘instrument’ of virtue, and its role in the promotion of morality replaced ‘the system of law’ (p. 158). In Sanahuja’s account in chapter 6, ‘Kantian cosmopolitanism’ is at odds with these approaches as Sanahuja characterizes Kant as the ‘keeper of the history of the rights of the individual’ (p. 14). According to her interpretation, he sided with the authors of the Second Scholastic period and returned to their understanding of the individual as the ultimate source of law, where the individual was considered ‘not only in his faculty as a moral agent but also as a holder of determinate legal rights, and understood as the basis and cause as well as the fundamental actor of all systems of law’ (p. 184). Kant is said to have gone beyond conventional approaches with his theory of property, his concept of ‘ends that are also duties’ and his notion of hospitality (see pp. 186ff.). Kant’s peculiar ‘twist’ in his theory is the acknowledgement of the ‘other’ as a proprietor (pp. 201–3).

Sanahuja’s overall interpretation avoids the complexities of Kant’s legal theory reconstructed by Sharon Byrd and Joachim Hruschka. They distinguish among iustitia tutatrix, which amounts to positive legislation to make rights possible, the iustitia distributiva representing the judiciary, and the iustitia commutativa referring to the public sphere of the market where people exchange external objects ‘in accordance with principles of justice’. According to their interpretation, cosmopolitan law or right offers an ordered commutative justice in the absence of a not yet fully achieved inter-state juridical condition with both iustitia tutatrix and iustitia distributiva. This interpretation challenges the centrality of cosmopolitan law asserted by Sanahuja (Byrd and Hruschka Reference Byrd and Hruschka2010; see also Cavallar Reference Cavallar2015: 51–5).

This book has its shortcomings, however. Some sentences are simply too long and awkward-sounding (see for instance pp. 11, 21, 128, 135). I am also not convinced by the very favourable interpretation of the Second Scholastic period, and the ensuing ‘debunking’ of the subsequent natural law theorists. Sanahuja tends to construct narratives that are in my opinion sometimes overly simplistic (see especially pp. 128–9 and compare Cavallar Reference Cavallar2002, Reference Cavallar2011 and Reference Cavallar2017). Moreover, the generic reference to ‘self-determination’ irrespective of the historical and cultural context is often anachronistic.

In sum, this is a good book and a very useful introduction to anyone interested in the history of cosmopolitanism or Kant’s cosmopolitanism in particular, and valuable in particular for the story of the prehistory of Kant’s cosmopolitanism, which is explored here more fully than in rival publications.