In Kant’s Political Legacy, Luigi Caranti carries out three distinct projects. First, he sets out to show that Kant’s legal and political philosophy contains the resources for constructing a novel and compelling account of the normative foundations of human rights. Second, he argues that Kant’s lessons about how to structure domestic, international and cosmopolitan political institutions in pursuit of peace have been misunderstood, and that we would benefit today from a hermeneutically more faithful understanding of them. Third, he aims to dispel misunderstandings regarding Kant’s views about historical progress and political agency, revealing them to be much less speculative and much more realistic than has generally been believed. The cumulative force of these distinct but related projects, Caranti hopes, is to vindicate the place of Kant’s political thought as an enduring and authoritative source of guidance as we navigate the increasingly complex political reality that has emerged since the end of the Cold War. In this review, I summarize his main arguments, and raise some critical questions about them.

The first part of the book is devoted to human rights. As Allen Buchanan has argued, the more entrenched human rights become, and the more serious the sanctions attached to their violation become, the more pressing is the need for defenders of human rights to offer an account of their foundational justification (Buchanan Reference Buchanan2010: 41). Such an account would tell us why human rights matter, why they are worthy of protection. Caranti devotes his efforts in this part of the book to developing and motivating the sketch of a Kant-inspired account that, he argues, can outperform all others on offer in the contemporary philosophical literature (Caranti Reference Caranti2017: 43, 57).

Following a typology originally proposed by John Tasioulas, Caranti distinguishes between ‘instrumental’, ‘non-instrumental’ and ‘practice-based’ justifications of human rights (Caranti Reference Caranti2017: 43). Canvassing the views of representatives of each of these justificatory strategies, he mounts a number of arguments against instrumental and practice-based justifications. His complaint against his favoured strategy – the non-instrumental – is that it does not go far enough. Representatives of this strategy hold that human dignity lies at the foundation of human rights, but because they regard the ascription of dignity to human beings as foundational, they are left with nothing to say when asked why human beings have this status (Caranti Reference Caranti2017: 6). This, Caranti thinks, has a mysterious air to it that encourages, or at the very least does little to address, practical scepticism about human rights. The best version of a non-instrumental strategy would be one that offered the sceptic a rational basis for accepting the normative force of such rights (Caranti Reference Caranti2017: 80).

Here, Caranti maintains, Kant’s doctrine that human beings have an innate right to external freedom ‘by virtue of [their] humanity’ (Metaphysics of Morals (MM), 6: 237) can be enlisted to deepen a non-instrumental justification (Caranti Reference Caranti2017: 19, 58). Taking sides in a long-standing debate among Kant scholars, he argues that the innate right to freedom must have its foundation in our status as moral agents. On Caranti’s interpretation, what grounds our dignity and makes us worthy of the respect human rights express is not our capacity for practical freedom – that is, our capacity to decide which among competing natural inclinations we will make the basis of our actions. Rather, what lies at the foundation of our dignity is our capacity for autonomy, which Caranti glosses as the capacity to act on the basis of moral constraints, free from the influence of all inclinations (Caranti Reference Caranti2017: 24–8). Whereas the value of practical freedom is conditional – its exercise, he notes, is consistent with monstrously immoral behaviour – the value of autonomy is not; rather, its exercise, on his view, has ‘intrinsic’ value (Caranti Reference Caranti2017: 61).

It is widely accepted in the literature on human rights that their justification ought to hold across diverse cultural and religious traditions. To meet this desideratum while building upon the Kantian account of human dignity, Caranti abandons Kant’s distinctive conception of autonomy. He argues that autonomous action is possible even when agents do not act in accordance with the categorical imperative. All that is required is that they act on the basis of a moral principle, which Caranti characterizes, very roughly, by means of features such as impartiality and fairness (Caranti Reference Caranti2017: 63–5). Further divorcing his account from Kant’s, Caranti also argues that autonomy is not a capacity unique to human beings. It is a capacity other animals possess, but which human beings realize to the highest degree in nature (Caranti Reference Caranti2017: 68–70).

While thought-provoking, Caranti’s attempt to strike out in a new direction will, I suspect, encounter much resistance. It is unclear, for instance, how much better positioned we are to address the sceptic about human rights with Caranti’s account than we were with non-instrumental accounts that bottom out in the ascription of dignity to human beings. Admittedly, his account gives us something further to say to the sceptic. But it is unclear that what we can now say has become any less mysterious. That may not be Caranti’s failing, however. Thomas Nagel may just have been right to warn that any attempt to explain a fundamental normative notion like dignity will involve ‘looking at the same thing in a different way’ (Nagel Reference Nagel1995: 92, cited in Caranti Reference Caranti2017: 6, 48).

There will be worries too, I think, about Caranti’s attempt to naturalize Kantian autonomy. Caranti slides between the claim that non-human animals are capable of action in accordance with some ideal that is not motivated by selfish inclinations (Caranti Reference Caranti2017: 69, 70), and the claim that they are capable of autonomous action, or action in accordance with moral principles that is motivated independently of all inclination (Caranti Reference Caranti2017: 57, 63). Furthermore, even if we can make sense of what it is to have the latter capacity to some degree, Caranti will have to do more work to spell out the implications a broadly shared animal capacity for autonomy would have for our practice of carving out a distinct set of rights that protect human beings qua human.

The second part of the book deals with Kant’s project for perpetual peace, a topic Caranti has addressed in previous work (cf. Caranti Reference Caranti2006). In a series of writings beginning with ‘Idea for a Universal History with a Cosmopolitan Aim’ (1784), Kant proposed domestic, international and cosmopolitan arrangements that, he claimed, would together promote the goal of a stable and lasting global peace. Which institutional reforms he was proposing, and on what grounds he was proposing them, have long been debated questions in Kant scholarship. Caranti’s primary contribution in this part of the book is to bring his position in this debate within Kant scholarship to bear on an assessment of Democratic Peace Theory (DPT), a successful research programme in the social sciences. Readers unfamiliar with either of these literatures will here find accessible (if understandably general) introductions to both.

Democratic Peace Theory is aimed at explaining a widely accepted datum: that democracies do not (or rarely) go to war with each other. The modern version of the theory had its inception in two essays by Michael Doyle (Reference Doyle1983a, Reference Doyle1983b). In them, Doyle drew substantially from Kant’s Toward Perpetual Peace (TPP) in order to construct an explanation of the fact of inter-democratic peace. Doyle’s essay inaugurated a successful research programme in the study of international relations that, Caranti suggests, has at times been quite influential among foreign policy elites and heads of state (Caranti Reference Caranti2017: 169, 206).

But here, where the legacy of Kant’s political thought has a rather strong claim to practical relevance, Caranti identifies a cause for concern. DPT, he argues, has distorted the lessons Kant meant to impart (Caranti Reference Caranti2017: 108). Caranti invites the reader to conclude that this has led to the pursuit of policies that run counter to the long-term end they are meant to serve (see, for instance, Caranti Reference Caranti2017: 206). A confrontation between DPT and Kant’s original project, Caranti suggests, can help us rethink the normative implications of the contemporary theory (Caranti Reference Caranti2017: 206) and even address some of the empirical challenges it has faced (Caranti Reference Caranti2017: 8–9).

Caranti expends the most effort defending his claim that DPT has distorted Kant’s original ‘model’ or ‘theory of peace’ (Caranti Reference Caranti2017: 107). He devotes the most extensive chapter in this part of the book to introducing and defending an interpretation of Kant’s project for perpetual peace, focusing on aspects of that project that contrast with its reception within Democratic Peace Theory. In the subsequent chapter he turns to an exposition of the basic claims, and the historical development, of the DPT research programme. In a final, brief chapter, he catalogues and discusses the main differences between the presuppositions and policy recommendations of Kant’s project, on the one hand, and those of DPT, on the other.

In the historical and political writings in which Kant developed his project for perpetual peace, he seems ambivalent about whether peace demands the establishment of a (federal) world republic, or merely of a voluntary league of nations. The most compelling interpretations of his project in the scholarly literature have attempted to resolve this ambivalence in one of two ways. Those we might call ‘sovereigntists’ read passages in which Kant discusses the ideal of popular sovereignty as evidence that he rules out, on normative grounds (and not merely on grounds of infeasibility), any form of compulsory governance above the level of the state. Instead, they maintain that the goal of establishing perpetual peace demands no more ambitious an international structure than a voluntary league of nations (see Maus Reference Maus2006). Those we might call ‘transitionalists’ have argued that popular sovereignty represents merely a constraint on how a federal world republic is to be achieved. States may not be forced to join such a federation, but the ideal of perpetual peace demands that they eventually do so. On this view, Kant proposes a league of nations as a transitional phase intended to secure the conditions for the stable and non-coerced emergence of a federal world republic in the long term (see Kleingeld Reference Kleingeld2004, Reference Kleingeld2012).

Caranti falls squarely within the sovereigntist camp (see Caranti Reference Caranti2017: 149–50, 224), but his defence of that position on textual grounds leaves something to be desired. For instance, he maintains that Kant thought that there was a conceptual incompatibility between the idea of a state of states and the sovereign status of a domestic republic (Caranti Reference Caranti2017: 150). But, in her defence of transitionalism, Pauline Kleingeld has argued persuasively that the relevant passage in Toward Perpetual Peace (at 8:354, lines 3–15) does not support this claim. Instead, what Kant is pointing out is that there is a conceptual incompatibility between the idea of the right of nations and the institutional model of a unitary world state – one into which all states would merge. Without a plurality of states, the right of nations would be an empty concept (see Kleingeld Reference Kleingeld2004: 311–3). But this has no bearing on the institutional model of what, in Religion within the Boundaries of Reason Alone, Kant calls a ‘federation of nations united in a world-republic’ (6: 35). Though Caranti discusses Kleingeld’s work, he does not address this particular argument of hers, and I was left wondering why he is not persuaded by it.

While Caranti’s sovereigntist interpretation of Kant’s project for perpetual peace awaits a more thorough defence, his efforts to bring Kant’s original position into productive conversation with contemporary DPT do not stand or fall entirely with that interpretation. For instance, transitionalists can find common cause with Caranti when he insists that Democratic Peace Theorists have been too quick to assimilate the concept of a Kantian republic to the concept of a liberal democracy (Caranti Reference Caranti2017: 139–40). Similarly, transitionalists can accept Caranti’s insistence that a Kantian league of nations, whether merely transitional or final, ought to be inclusive not only of liberal-democratic states, but also of non-liberal states (Caranti Reference Caranti2017: 146–8), and that Kant’s conception of cosmopolitan right extends to more than commercial relations among states (Caranti Reference Caranti2017: 154–6).

In the third and final part of the book, Caranti offers a (by his own admission) cursory interpretation of Kant’s views of historical progress and political agency, as well as the role these play in the justification of his political proposals. Though this part is considerably shorter than the other two, taking up roughly one-fifth of the whole, it contains some of the most valuable and exciting ideas in the book. In the remainder of this review, I will focus on the issue of historical progress, though Caranti’s attempt in the final chapter to extract a theory of political agency from Kant’s discussion of the ‘moral politician’ and the ‘political moralist’ is also worthy of engagement (TPP, 8: 372).

Kant’s progressive view of history has long been a stumbling block to the acceptance of his project for perpetual peace. Kant appears sometimes to want to convince us, on the basis of a teleological view of nature, that the human race is progressing inexorably towards perpetual peace (see e.g. TPP, 8: 360–2). But that view of nature has long been eclipsed by later developments in the natural sciences, notably by the Darwinian revolution in biology (Caranti Reference Caranti2017: 212–13). Furthermore, belief in a progressive view of history seems to some today, in the wake of the horrors of the twentieth century, as a piece of Enlightenment dogma (Caranti Reference Caranti2017: 218). Yet, even if Kant’s view is interpreted more weakly, as meant only to reassure us of the feasibility of his political project, there are other grounds for scepticism. Kant suggests at times that we must accept the feasibility of the project on the grounds that perpetual peace is a command of reason, but like many, Caranti finds this unacceptable. It is wishful thinking to believe in the feasibility of a project merely on grounds of its moral desirability (see Caranti Reference Caranti2017: 223). Our obligation to work towards perpetual peace must rest on epistemic reasons for believing that Kant’s proposals are feasible (Caranti Reference Caranti2017: 10–11).

In two separate chapters, Caranti begins to develop an interpretation of Kant’s progressive view of history that can adequately help justify his political project without succumbing to these worries. Caranti’s strategy is to show that Kant’s conclusions about progress are separable from the teleological premises he endorses in his earliest sustained treatment of the topic in ‘Idea for a Universal History’. What emerges from Caranti’s reading is a view of Kant as engaged in social theorizing about the likely developmental tendencies of human societies, indistinguishable in kind from the sort of theorizing we find among contemporary social and economic theorists (Caranti Reference Caranti2017: 233–4). Caranti argues that we ought to understand Kant as holding that, given certain stable tendencies in human nature and certain stable features of the world human beings inhabit, progress towards perpetual peace is more likely than the alternatives (Caranti Reference Caranti2017: 221–2).

Further work is needed to show that Caranti’s interpretation enjoys substantial textual support in Kant’s writings, a task that would benefit from closer attention to Kant’s last sustained treatment of the subject of historical progress in The Conflict of the Faculties. Further engagement with the content of Kant’s view, so interpreted, is also called for, if the ultimate aim is to motivate Kant’s political project. An important point of reference here might be Habermas’s effort to engage with Kant’s philosophy of history in precisely the social-theoretic terms Caranti is urging (Habermas Reference Habermas2002). But Caranti has, in my view, identified a compelling but often neglected strand of Kant’s thinking about history and its role in grounding our judgments about the feasibility of working towards perpetual peace. His interpretation in these chapters presents a formidable, if yet to be fully developed, challenge to those who would consign this part of Kant’s thought to irrelevance.