This chapter explores the potential of the diverse field of just war theory for military education. Contemporary just war thinking takes place before the horizon of a polarised field of study (Clark, 2017, p. 331). On the one hand, one finds what has been referred to as the “traditional” or “conventional” approach that is commonly associated with Michael Walzer.Footnote 1 This approach argues for a collectivist, state-based understanding of just war. The Walzerian just war builds on the framework of international law and seeks to provide moral arguments that are of practical relevance to political and military decision-makers. On the other hand, so-called “revisionist” just war philosophers reject the collectivist starting point and advocate an individualist perspective instead. Commonly, revisionists draw their arguments from far-fetched hypothetical cases that bear little to no resemblance with real-world scenarios. Relatedly, they are mainly interested in what they call the deep morality of war, a highly idealised account of morality that takes no interest in the type of pragmatic compromises that underpin international law and the Walzerian just war. As a result of varied and fundamental disagreements, the exchange between the two just war camps has been limited.Footnote 2 Moreover, whilst both traditional and revisionist just war theory are based on deontological reasoning, with consequentialist elements predominantly present in the former,Footnote 3 there is also the distinct field of military virtue ethics. Rather than rights and obligations, it deals with the character traits that are presumed to be important for members of the armed forces. Although military virtue ethics is part of just war theory broadly conceived, deontological and virtue ethical reasoning are rarely combined in the literature.

Instead of discussing the substantive norms governing war, we focus in this chapter on these different theoretical approaches within the broad field of just war theory. More specifically, we critically evaluate revisionist just war theory for the purpose of educating future military leaders. Traditional just war theory and military virtue ethics have an important place in most military curricula. Walzer’s Just and Unjust Wars (1977/2015) remains a standard text on just war theory at many military academies.Footnote 4 Whilst jus ad bellum is primarily relevant to statesmen and political leaders, it is assumed that future military leaders nonetheless require an understanding of the ethical principles underlying their task, the reasons for deployment, and the arguments used in the public debate.Footnote 5 Jus in bello specifically addresses military leaders and relates to the ethics of the profession of arms. Military virtue ethics is also widely taught at military academies as the theoretical basis for building character, including cultivating the virtues that help military professionals perform well in the extreme circumstances of war. But how about revisionist just war theory? To date, the revisionist approach has struggled to gain traction in the curricula of military academies. Traditionalists question the practical relevance of revisionist just war thinking, relegating much of it to the academic ivory tower. This seems unsurprising, as within the field of military ethics it is assumed that when something is not “helpful in providing real-world guidance for policy-makers, military commanders and leaders, or operational decision-making,” there might be a place for such theorising in the discipline of philosophy, but unless it “can be brought to bear on the professional activity of military personnel in some meaningful way, they are academic exercises of interest primarily to other academics within the same field” (Cook & Syse, 2010, p. 120).

The question is: should we dismiss revisionism for the purpose of military education or can it provide valuable new insights that escape the other approaches? Whilst in our work we generally see more merit in traditional just war theory, we think that the role of revisionism deserves more attention than it has received so far.Footnote 6 In order to assess that role, we seek to connect just war thinking to the German and Dutch leadership concepts: Innere Führung and the ideal of “thinking soldier.” In the following two sections, we will discuss traditional and revisionist just war theory. Subsequently, we will provide an overview of the German and Dutch leadership concepts. We side with critics who argue that the practical applicability of revisionist just war thinking is limited. However, we will argue that whilst the space for reflective moral decision-making is very limited on the battlefield, revisionist just war thinking may play an indirect role at military academies. The benefit of revisionism, we will argue, ties into the ideal of Innere Führung and the “thinking soldier.” At the same time, however, its shortcomings do not only underline the benefits of traditional just war theory, they also bring us back to the importance of virtue ethics and character building in military education. Knowledge of rules and principles and the ability to critically reflect on that normative framework only takes us so far. Doing “the right thing” in the extreme circumstances of war requires not only knowing what to do, but also requires the motivation to do it. In other words, the ethical competence of military leaders must reflect a cognitive and motivational dimension. Strengthening such competence benefits from a comprehensive theoretical basis; one that combines the various theoretical approaches.

Walzer’s Just War

Walzer has always been sceptical that philosophical reflection alone can address the moral questions arising in war. His is a “practical morality,” which does not directly engage with “the most profound questions of moral philosophy” (Walzer, 2015, p. xxii). Relatedly, Walzer advocates a case-based approach to just war. For him, it is the reality of war, as expressed in the experience soldiers gain on the battlefield, that provides the material to argue about the morality of war. An important underlying assumption of conventional just war theory is that war is an exceptional moral domain which is distinct—although not separate—from normal morality. There are several reasons to defend such “exceptionalism:” the magnitude and scale of war as a violent conflict; the fundamental political interests at stake; the uncertainty and fog of war; and the general non-compliance with fundamental moral norms such as the obligation to respect the right to life (Shue, 2008, p. 88; Walzer, 2015, pp. 335–345).

Taking the “legalist paradigm” as his starting point allows Walzer to follow the laws of war closely.Footnote 7 His is therefore a legalistic theory, and some (see, e.g. Lazar, 2017, p. 38) have argued that his main objective is to provide the laws of war with a moral foundation.Footnote 8 Nonetheless, Walzer considers positive international law to be “radically incomplete” (2015, p. xxvi). Moreover, the “war convention” is comprehensive; it consists not only of legal regulations, but also moral norms, customs, professional guidelines, religious/philosophical principles and reciprocal understandings that shape our judgements about military action (Walzer, 2015, p. 44). It is, in other words, the agreed upon set of norms and values on which the international moral and legal order is based. Given the importance of political sovereignty and territorial integrity in that international order, it is states that are taken to be the most important actors.Footnote 9 However, Walzer states that the war convention is “necessarily imperfect […] because it is adapted to the practice of modern war. It sets the terms of a moral condition that comes into existence only when armies of victims meet” (Walzer, 2015, p. 45). With his account of just war, Walzer created a normative common language that enables concrete judgements in the political reality. It is a practical moral theory, in line with international law, congruent with common sense morality, and providing specific guidelines regarding military behaviour in the extreme situation of war.

Those specific guidelines can be broken down into three branches: jus ad bellum entails norms on the justification of war, jus in bello norms on proper behaviour in war and jus post bellum norms on how to realise a just peace.Footnote 10 Central in Walzer’s just war theory and in international law is the “independence thesis:” jus ad bellum and jus in bello are separate branches. Jus ad bellum is asymmetrical, whilst the subsequent warfare is governed by moral rules that are the same for just and unjust combatants alike. Unlike jus ad bellum, jus in bello is symmetrical; combatants have equal rights and obligations in war. That means that whilst non-combatants are immune and cannot be intentionally targeted, combatants are equally liable to be killed and equally permitted to kill their adversaries. This central idea is reflected in international humanitarian law, which determines that its norms apply to all those concerned and imposes the same obligations on them. Whilst Walzer starts his argument stating that he does not consider the legalist paradigm as sacrosanct (Walzer, 2015, p. xxvi), he nonetheless employs the legalist paradigm as a “frame” (Johnson, 2014, p. 5). This then, lets him accept positions that earlier just war thinkers would have rejected as morally indefensible, such as his argument for a moral equality of combatants that abandons the requirement to discriminate between those who fight a just war and those who fight an unjust war.

The Revisionist Critique

Revisionism is an umbrella term for a critical current within just war theory.Footnote 11 Although there are many different revisionists, they generally set out to revise the norms of traditional just war theory. Moreover, they are like-minded when it comes to the theoretical underpinnings on which their theory is based. The starting point of these theorists is not the legalist paradigm, or the reality of warfare, or historical just war theory. They take Walzer’s theory as the “conventional” ruling theory that must be checked for logical incoherence with the goal of constructing a better theory. In order to do that, they rely on Rawls’s method of reflective equilibrium (Rawls, 1971/1999, pp. 18–43).Footnote 12 The main objective of revisionists is to write novel philosophy on war-related issues such as the ethics of harming, the duty to save, or political authority. It seems fair to state that most revisionists do not share Walzer’s ambition to provide a practical morality that can easily be taken to inform political and military decision-making. The foremost expression of their limited interest in the experiences men and women undergo on the battlefield is their use of far-fetched, oftentimes other-wordly, thought experiments.Footnote 13 Consider, for example, the following thought experiment Helen Frowe provides in the context of self-defence:

Ray Gun

Falling Person has been blown by the wind down a well, at the bottom of which you are trapped. Falling Person will crush you to death unless you vaporise her with your ray gun. If you do not vaporise her, your body will cushion Falling Person’s landing, saving her life.Footnote 14

This methodology, i.e. the use of such thought experiments as building blocks in the reflective equilibrium, fits well into the abstract process of conceptual analysis that characterises analytical philosophy. Unsurprisingly, however, non-revisionists question the practical relevance of such hypotheticals.

Revisionists furthermore object to the important position of the state in Walzer’s theory. They reject what they see as a collectivist approach to war and hold that the responsibility for killing resides in the individual. In contrast, they advocate an approach they refer to as “reductive individualism.” That approach is reductive because it assumes that the rules that regulate killing in war can be reduced to those regulating interpersonal killing outside of war (Frowe, 2014, p. 13). At the heart of reductivism is the conviction that there is only one set of moral principles which applies all the time; there is nothing inherently special about war. Consequently, the idea that there are different moral domains such as war and peace is a non-starter for revisionists. At the same time, most revisionists are individualists, as they argue that moral theory must concentrate on individuals rather than collectives.

As a result of these fundamentally different underpinnings, revisionists object to key elements of Walzer’s theory. Aside from aiming to revise jus ad bellum, many revisionists have targeted the rules of jus in bello, including the independence thesis, and consequently the moral equality of combatants and the immunity of non-combatants.Footnote 15 Following reductive individualism, war is simply an aggregate of just or unjust acts of individual self- and other defence on a large scale.Footnote 16 This means that, like jus ad bellum, jus in bello is asymmetrical: unjust combatants are responsible for posing an unjust threat and are therefore liable to attack. Consequently, just combatants are permitted to kill unjust combatants, but not vice versa, since just combatants have done nothing to make themselves liable to be killed. Put differently, in order to be subjected to force, the unjust threat must have forfeited its right not to be harmed, which revisionists tie to the just cause of self and other defence. McMahan argues that: “the principles of jus ad bellum apply not only to governments but also to individual soldiers (agents), who in general ought not to fight in wars that are unjust. It denies that jus in bello can be independent of jus ad bellum and concludes that in general it is not possible to fight in a way that is objectively permissible in an unjust war” (McMahan, 2012). There is no moral equality of combatants; unjust combatants cannot do anything right, except lay down their weapons (Lazar, 2017, p. 38). This approach, then, also challenges the principle of non-combatant immunity. When civilians contribute to an unjust threat, or when they are morally responsible for such a threat, they make themselves liable to be killed. According to the revisionist approach, some non-combatants can be legitimate targets.

In summary, the objective of revisionists is to formulate norms that are derived from abstract moral principles. Through this abstraction and the use of hypothetical examples, an ostensibly greater understanding is gained. As Frowe (2014, p. 5) puts it succinctly: “Stripping away the detail can enable us to identify general principles that can be obscured by the intricacies of historical cases.” Complex reality can mask things, it is assumed, and norms can be more easily identified without the fog that surrounds historical events (Frowe, 2016, p. 1). The practical objective, however, hardly comes into focus as a result. Revisionists generally show little interest in the war conditions in which moral decisions are made. As a result, whilst their arguments may be philosophically coherent, they are also difficult to apply. Do combatants have enough knowledge of political dynamics to judge whether their war is just? Is that knowledge available to the general public at all? Are they able to determine which individuals amongst the combatants and civilians are liable to attack, and who are not? And in the extreme conditions of war—characterised by stress, agony, time pressure, limited opportunities for rational decision-making—can combatants make such judgements? The time for reflective moral decision-making on the battlefield is very limited indeed. In war, therefore, the guidance provided by revisionist theory can hardly be followed.

Therefore, unsurprisingly perhaps, revisionist just war thinking has not featured in any prominent way on the curricula of military academies. The reasons seem obvious: military academies educate and train future military practitioners. The focus is on providing action-guidance, not on creating philosophers. In addition, as will be discussed in the next section, the revisionist challenge to Walzer’s theory comes with the danger of undermining the laws of war. Relatedly, the individualist understanding of revisionists is in tension with the collectivist and hierarchical understanding that undergirds the organisation of the military profession.Footnote 17 These weighty reasons notwithstanding, we will argue in the following that there is a limited place for revisionist just war thinking in military academies.Footnote 18 As we will demonstrate, that place cannot be where soldiers are being prepared for practical moral decision-making on the battlefield. Rather, revisionist just war thinking could play a role in the endeavour to produce the type of military leaders imagined by the German and Dutch leadership philosophies.

Military Leadership Philosophies

What is the relevance of revisionist just war theory for the purpose of military education? Before we can properly explore the educational aspect of just war thinking, and the role of revisionist just war theory within it, we need to turn to the German concept of Innere Führung (leadership development and civic education) and the Dutch concept of the “thinking soldier.”Footnote 19 Once we have established the relevance of these conceptualisations, we will be in the position to determine the limited place for revisionist just war thinking in military education. The German and Dutch leadership philosophies are related; we identify interesting parallels between the German Innere Führung and the Dutch conceptualisation. Both share the objective of educating self-reflective and politically sensitive soldiers who act responsibly and take responsibility for their actions. Seeing the ideal military leader as a critical thinker—an individual who is academically trained, aware of his/her own moral norms and values, and sensitive to his/her place in the social and political context—can help us locate a modest slot for revisionist just war thinking.

Seeking to learn from Germany’s militaristic past, the Bundeswehr is supposed to be anchored at “the centre of society” (Bundesministerium der Verteidigung, 2008, § 101). Its soldiers are considered to discharge their responsibilities when they “out of inner conviction, actively stand up for human rights, freedom, peace, justice, equality, solidarity and democracy as the guiding values of our state” (Bundesministerium der Verteidigung, 2008, § 106). Command, obedience and ethics are the key principles of this concept and reflect the “remarkable trinity of political purpose, constitutional essentials, and soldierly command and discipline in the blast of fighting, anger, and hatred native to war and political violence in its variety” (Abenheim & Halladay, 2016, p. 3). One element of this understanding is the requirement that soldiers “think for themselves, rather than obey blindly” (Bundeswehr, 2021). Some (e.g. Hartmann, 2016, p. 23) argue that it is in this “primacy of conscience” where the German leadership philosophy differs from that of some of its allies. In a nutshell, the idea is to foster an environment where Innere Führung is internalised; the thinking soldier, who actively grapples with the difficult decisions he/she may be required to take, becomes the ideal soldier: “Innere Führung forms the spiritual and moral basis of the armed forces” and “it enables acting upon insight (emphasis added)” (Bundesministerium der Verteidigung, 2008, § 107). That said, as Peter Olsthoorn (2016, p. 35) notes, it is important to point out that Innere Führung is not meant to resemble simply “an internal moral compass” in which societal values play no role: “One of the ideas behind Innere Führung is that soldiers should disobey orders that are manifestly unethical; they are expected to think for themselves. But that does not mean that anything goes; the values that should guide that independent thinking are clearly societal.”

As the previous citation invokes the concept of a thinking soldier, it acts as a bridge to the Dutch leadership philosophy. Central in the education of the Netherlands armed forces is the ideal of the thinking soldier.Footnote 20 It assumes that the intellectual and pragmatic challenges of today’s complex security environment make it essential for “officers to keep a broad focus and an open mind and, most importantly, to take responsibility for their actions, as these do not only affect their own lives, but the lives and livelihoods of others as well” (Oonincx, 2019, p. xi). The complexity of the military profession, in other words, requires a combination of academic education and a more practical preparation for the military profession (Oonincx, 2019, p. vi). Officers need both academic skills and the ability to act effectively in practice. The concept of the thinking soldier builds on Donald Schön’s idea of a “reflective practitioner;” an academic practitioner who continuously questions, reflects and reforms assumptions, and in this way, is aware of his/her (implicit) knowledge and learns from experience (Schön, 1992). Such a practitioner comes up with creative practical solutions on the basis of academic reflection and analysis, in complex situations where a simple application of rules or academic knowledge will not do the trick. The concept of the “thinking soldier” reflects the idea that military leaders must be scholars and soldiers; they combine both the “habitus of the scholar,” i.e. critical thinking, analysis, systematic doubt and the “habitus of the officer,” i.e. authority, agility and the ability to command (including swift decision making, analysis with limited information, pragmatism) (Jansen et al., 2019, pp. 340–341). In that way, “a reflective practitioner is a craftsman thinking about his job by asking questions” (Bijlsma, 2019, p. 117). Ger van Doorn (2019, pp. 162–163) subsequently draws specific attention to ethical reflection. He sees a reflective practitioner as someone who constantly reflects on the norms and values that ground our behaviour, and who is able to transform that into (self-) insightful action in daily practice. It is the combination of ethical reflection and operational action that creates thinking soldiers (Van Doorn, 2019, p. 178).Footnote 21

Critical Thinking and Revisionism

Having laid out two specific contemporary military leadership philosophies, does that indicate a place for revisionist just war thinking? As stated in the introduction, given the practical orientation of military education, traditional just war theory has been taught predominantly at military academies. Nonetheless, we believe that the revisionist just war can play a helpful role in educating military decision-makers, as it connects to the rationale behind Innere Führung and the thinking soldier. Returning to the disagreement between Walzerians and revisionists regarding the moral equality of combatants and relatedly the relationship between the morality and laws of war, we have seen that revisionists, much more empathically than Walzerians, demand that combatants engage with the jus ad bellum decision, not just with jus in bello decisions. In fairness to Walzer, he does not entirely disconnect jus ad bellum and jus in bello decisions. Discussing the Second World War on the German side, which for Walzer was the prototypical unjust war, he argues (2015, p. 345) that the best moral option would have been for Wehrmacht soldiers not to participate in it: “…soldiers have a right to refuse to fight in a war they believe to be unjust; … But it is an act of heroism, and it can’t be morally required; unheroic conduct isn’t criminal conduct.” In a sense, one might add, Walzer is again suggesting a pragmatic compromise here. Many soldiers do not have the information or the education to judge the justifiability of the war they are called to fight. However, Walzer clearly accepts exceptions to what might be called a presumption to participate.

Revisionists, of course, go much further than Walzer regarding the responsibility they allocate to the individual and the decision to participate in war. This might just be what Innere Führung and the thinking soldier require. As Bernhard Koch (2019, p. 7) notes, in the eyes of revisionists, soldiers “must therefore ensure they are aware of the ethical reasons for their deployment, and cannot simply shrug off their moral responsibility as a question of command and obedience.” Whilst the jus ad bellum decision remains a political decision, we think that having future military leaders engage with the moral arguments of revisionists, some of which challenge the “traditional” account of just war and the established laws of war, can create more conscientious practitioners. It allows a deeper understanding of the normative framework and fosters the political and social sensitivity that is central in these leadership philosophies. In that sense, revisionist just war thinking can help strengthen ethical competence.

To see how this could work, let us take a closer look at what ethical competence entails. Gerhard Kruip (2019) makes a helpful distinction between two levels of ethical competence.Footnote 22 Firstly, there is a cognitive, argumentative dimension. That enables officers to test the moral purchase of norms and to judge the morality of specific situations. However, the cognitive, argumentative dimension marks only a partial competence and needs to be combined with the emotional and motivational dimension. The latter aspect relies on internalisation based on examples, encouragement and recognition: “That is, if we wish to derive individual conclusions for action from moral norms, we have to apply those norms to specific situations and also analyse these situations as best we can” (Kruip, 2019, pp. 12–13). Revisionist just war thinking could be employed to analyse the moral purchase of Walzer’s traditional just war. Pointing to the chasm between the ideal-type morality revisionists call the deep morality of war and the established laws of war that form the bedrock of Walzer’s theory, would enable military decision-makers to better understand the uneasy compromises that have resulted in today’s laws of war—and why they need to be upheld.Footnote 23 Whilst discussion may lead to the conclusion that revisionists are right that just and unjust combatants do not face each other as moral equals, it would also point to the weighty moral reasons for granting equal rights to combatants on both sides. In other words, revisionists reveal both weakness and strength of the Walzerian theory. Whilst Walzerians might be wrong in the ideal, granting equal rights to combatants on both sides is a pragmatic compromise that is instrumental for the constraint of war. Therefore, equipping military leaders with a grasp of where this compromise originates, and why it matters, will help them put it in action. In particular, awareness would be raised that an asymmetric application of the laws of war would potentially have dramatic consequences vis-à-vis how wars should be conducted.Footnote 24

As David Rodin and Henry Shue (2008, p. 7) note, “it is likely that most combatants would, rightly or wrongly, view themselves as fighting for the just side and would therefore attribute to themselves any asymmetric war rights reserved for the just side. In this way, the overall destructiveness of war would go up with no strategic advantage being reaped by the genuinely just side.” Engaging with the revisionist critique could point to the conceptualisation of the laws of war as a non-ideal compromise that has been accepted internationally and, therefore, functions as an important mechanism of restraint in war. It could thus inform soldiers about the need for a pragmatic objection against aligning the “deep morality of war” with the laws of war, which even McMahan himself accepts.Footnote 25

It goes without saying that the approach of scrutinising and consequently re-affirming the established laws of war is intellectually demanding of military leaders. It is also an undertaking that needs to be facilitated carefully in order not to risk the fragile construct of the laws of war. Jeremy Waldron, for example, cautions moral philosophers to “take special care” when evaluating and challenging the laws of war: “These laws are not robust, they are not particularly resilient, they are difficult to enforce, and they depend largely on the voluntary self-application of problematic and constable norms to the conduct of groups of men who find themselves in circumstances of mortal danger” (Waldron, 2018, p. 81). The fear, that is, is that whilst revisionist just war thinkers may be able to undermine the established laws of war, they are unable to put in place laws that align with the morality of war more closely.

We share Waldron’s concern about the potential negative repercussions of revisionist just war thinking for the conduct of war. An ostensibly easy solution would be to simply ignore it in military education: “These are the laws of war and you must not question them.” In contrast, we think that we can do better. In line with the concepts of Innere Führung and the thinking soldier as we understand it, we propose to engage and reflect on those laws with future military leaders. Rather than presenting the established laws of war as a robust and resilient body of law that has no moral alternative, we propose to discuss it openly as the perhaps uneasy but necessary moral compromise that it is. With the help of the revisionist argument, officers would be able to better understand its moral foundations and its shortcomings, but also internalise why it must not be undermined. In that way, we believe, “thinking soldiers” would uphold the laws of war by acting upon insight, rather than simply obeying what they are told. As a result, the revisionist challenge to Walzer’s traditional just war, and the laws of war on which it is built, can make a valuable contribution to our military academies.

A Comprehensive View on Just War Theory

Whilst we have argued for a modest role for revisionist just war thinking, it should come as no surprise that we consider it to have limited value for other crucial elements of military education, especially with regards to preparing soldiers for the moral and legal questions that await them on the battlefield. Revisionist methodology, especially the individualist underpinnings and the use of other-worldly thought experiments, removes them from the reality of war. It seems questionable that this can helpfully inform military decision-making. In that sense, we are sympathetic to Walzer’s engagement with the experiences men and women gain on the battlefield as a tool to derive norms but also test moral judgements. Like Walzer’s conceptualisation of just war, ours seeks to be a realistic one that is capable of providing action-guidance. Such an account departs from the collectivist nature of warfare, the institutional context and the social practices related to it. Our concern is that, because of not translating the proposed norms to the context of war, revisionist just war theory loses the “close linkage of decision-making and concrete action” (Reichberg, 2018a, p. 65) that was a central aspect to earlier modes of just war thinking and that remains of crucial importance for practitioners today.

Moreover, and returning to Kruip’s distinction of two levels of ethical competence, revisionists do not aim to capture the emotional and motivational level. It is here where we think that training in the military virtues is especially important, complementing knowledge of the laws of war and traditional just war theory: it strengthens the emotional and motivational dimension of moral competence that escapes revisionists.Footnote 26 Especially given the complex security environment, military leaders will be confronted with moral dilemmas, a lack of clear legal answers, or inclinations not to do the “right thing.” David Perry (2016, p. 5) rightly notes that “ethical decision-making cannot be reduced to a short checklist or model”; it requires a wide range of moral emotions. No checklist, model, or set of norms can provide answers in every situation. In the same vein, Désirée Verweij and Tine Molendijk show that such a check-list view, separating the various just war criteria and cutting loose the justification of the use of force from the justification of warfare, risks losing sight of the context in which force is used and specifically the purpose of the endeavour itself, i.e. correcting the wrong that was the cause for war (Verweij and Molendijk, 2019).Footnote 27 Therefore, we think that a thorough understanding of the laws of war and their moral foundations as explicated in just war theory, in addition to a strong moral compass and cultivated virtues, best supports the decision-making process in challenging situations.Footnote 28 As stated in the introduction, however, the various theoretical approaches within the broad field of just war theory are rarely combined.

Interestingly, as an engagement with the just war tradition demonstrates, thinkers as early as Thomas Aquinas in the thirteenth century, who himself drew on the thinking of Aristotle, emphasised the importance of virtue for the military profession.Footnote 29 Aquinas was well aware of the fact that soldiers need virtues in order to deal with the emotions and passions that inevitably arise in mortal combat. Aquinas’s just war, as he let it unfold within an account of the virtues, recognises that there is no time for imaginative modelling in the heat of battle there: “Aquinas’s virtue approach has, by contrast, the advantage that it is designed specifically for such settings; thus instead of first separating reflection from practice and then facing the challenge of reuniting the former with the latter, Aquinas attempts a unified account that joins the two from the beginning.”Footnote 30 Fast forwarding to the contemporary era, it is interesting to note that the revival of just war theory that Walzer triggered with his Just and Unjust Wars coincided with a resurgence of virtue scholarship. However, as Michael Skerker notes (2019, p. xxv), the two revivals did not immediately lead to a “profusion of texts about military virtue.”

Neither are these two approaches, just war theory and military virtues, often merged together. There are exceptions, though, and we think that such comprehensive accounts of just war theory are especially valuable. Allen Buchanan, for example, assumes that the goal of just war theory is not limited to listing theoretical justifications (such a “checklist” of criteria), but also includes providing “directly action-guiding rules,” guidance for the evaluation of institutional processes, criteria for the evaluation of the laws of war, the decisions of leaders, and social practices, plus an account of the virtues of leaders.Footnote 31 Another exception is A. J. Coates (2016, pp. 1–19), whose secular account draws on the classical idea of bellum justum. He argues that the key determinants of justice in war are the moral dispositions of combatants. It is not only about rules and principles, but also virtues and vices. Since virtues and vices are expressions of combatants’ moral character, they therefore incline or disincline towards moral or immoral conduct. Coates (2016, p. 15) also emphasises that moral agency is both cognitive and volitional. Consequently, even if someone knows the correct action to take, that does not necessarily mean that this person will act accordingly. Therefore, the moral agent needs correctly-ordered virtues in order to “will” the right action.

Concluding Thoughts

We have argued that there is a modest place for revisionist just war thinking in the education of military decision-makers. Engaging with the revisionist challenge to traditional just war theory facilitates a deep understanding of the laws of war and an awareness of the necessity to uphold them, which is based on insight, not just on obedience. Nonetheless, we have also pointed out a number of drawbacks of revisionist just war theory: the risk of undermining the laws of war, the inability to provide action-guidance (since rules are derived from abstract moral principles and hypothetical thought experiments), and the neglect of the internal motivation crucial on the battlefield. There is some, albeit limited, value in integrating revisionism in military curricula.

For the purpose of military education, we especially see merit in a comprehensive approach (traditional just war theory with reference to the revisionist critique) that joins together reflection and practice. Such an approach is likely to be most effective at preparing military practitioners to bear what Martin Cook (2006, p. 27) refers to as the officer’s “weight of responsibility,” namely, to “thoroughly incorporate thought about the jus in bello side of just war into standard operating procedure.” And whilst perhaps less obvious, the ability to reflect on political jus ad bellum issues further strengthens the ethical competence of military decision-makers, as it deepens insight into the nature of their task and enables them to position themselves in the wider society.Footnote 32 As Jansen and Verweij (2019, pp. 61–62) put it, the challenges of today’s security environment require “a certain level of self-realisation and individual development in dialogue with the wider (globalised) world.” Such reflection on the legal and moral rules strengthens the internal motivation to act on them, and as such, helps to increase compliance with the laws of war. Importantly then, this must be complemented by a virtue ethics approach, which is essential for further strengthening the second dimension of moral competence and helps to internalise the moral and legal rules. Given the extreme circumstances and the confrontation with violence, military leaders need the strength of character to do the right thing in complex situations, despite risks, and given the multiple demands and values at stake. When it comes to the value of just war theory for military education, we think that a practically-oriented and unified approach, one that draws on reflection and virtue, is most helpful in achieving the ideals of Innere Führung and the “thinking soldier.”