Any work which sets out not only to defend the just war tradition, but to argue for the justice of particular historical conflicts is bound to court controversy. When the particular conflicts defended include ‘the British prosecution of the First World War in 1914–18’ and ‘the American-led Coalition's invasion of Iraq in 2003’ (p. 331) then the task would for many critics of just war seem somewhat ludicrous. So it is to the credit of Professor Nigel Biggar that he not only provides robust arguments for his position, but in doing so provides a lesson in moral theological engagement with concrete cases. Biggar argues that the moral theologian should not rest in the realm of abstract principles, but should be engaged in helping decision-makers reach concrete conclusion (p. 333). The book can thus be understood as appealing not only to specialist theologians, but to all who have an interest in war (which is arguably all of us). His own interest is not hidden, and in the introduction he admits his life-long fascination with war, a passion which he puts to work in using the wide and varied sources from which he draws across several disciples.

The book is not a manual setting out classical just war theory and seeking to defend it in a number of theses. Rather, it assumes some familiarity with the main tenets of just war theory. Neither is it a work which sets out systematically to explore just war theory; which is not to say that important conclusions are not developed in the course of Biggar's defence. Some of the materials used in the book come from previous publications, so we should not expect the unity of a systematic work, nevertheless Biggar has arranged the materials in an order which brings a progression through the two halves of the book.

The first half is concerned with defending just war against critics within the Christian tradition. Here Biggar faces the challenge of explaining how war can be the expression of christian love. In response to this he lays out his own position as an expression of Augustinian Christian Realism, arguing that it is wishful thinking to imagine that war will somehow go away if our response to injustice is pacifism. He engages with some of the leading proponents of christian pacifism, taking on their readings of scripture and questioning their understanding of justice, love and forgiveness. Next he looks at some of the key principles of just war tradition, the principles of double effect and proportion, concluding this first half of the book with a concrete examination of how to apply the principle of proportion to the First World War.

The second half of the work begins at chapter five and Biggar's defence of just war against the arguments developed by David Rodin. Here Biggar moves from engagement with criticism from within the christian tradition to criticism from a modern liberal thinker in the analytical tradition. This shift enables Biggar to engage with the themes of legality and morality, and the relationship between them. Here he defends natural law against legal positivism, arguing that nations have prior moral responsibilities which entail they can under certain circumstances justly engage in armed conflict without the backing of international law. Concrete application is given in this case by an analysis of the morality and legality of NATO's intervention in 1999 in Kosovo. Here again Biggar combines careful analysis of a particular conflict with his wider theory of the relationship between morality and law, set in the context of his Augustinian Realist theology.

The final chapter is potentially the most controversial, defending the justice of the 2003 Iraq war. Biggar is aware of this and as such uses it to show how the various elements developed throughout the book can be brought together to provide a robust defence of war. Thus he seeks to produce a defence against the strongest case his opponents might throw at him, in order to counter the accusation that his work avoids discussing hard cases, and thus cannot be taken seriously as a defence of just war.

From the above outline it is clear that Biggar had engaged upon an ambitious project, which threatens to win him few friends, but many detractors. As a project some may view it as somewhat over ambitious, but I am inclined to agree with his assessment of the responsibilities of the moral theologian to engage with concrete cases, even if this risks overstepping competencies. When engaging with such a range of fields (history, legal theory, military strategy etc.) there is always the danger that the real experts will dismiss the claims of the theologian. But there is also room for dialogue and mutual enrichment, which is of immense value when academics leave the class room and come face to face with realities which cannot be neatly divided into a modern curriculum.

The work contains some specific weaknesses, such as Biggar's analysis of intention and double effect. Here the influence of New Natural Law theory leads Biggar to argue that intending to take life is always wrong (directly acting against one of the basic goods), and thus those who are on the side of justice and kill in war cannot be intending to do so. Since most killings in war are not accidental Biggar has to find a way to explain how non-accidental killings are not intentional. This entails performing gymnastics with the notion of intention, to argue that a soldier who deliberately kills an enemy does not intent to do so if the soldier does not want to kill the enemy (e.g. if another means of removing the enemy from the battle were possible). A more general question the book raises is in regard to its underlying theological commitments. We have noted that Biggar engages an Augustinian Realist perspective, but what form of Augustinian does he support? His Protestantism (p. 241) makes him suspicious of claims to the establishment (past, present or future) of international human consensus and harmony. Yet the just war theory which he seeks to defend is itself the product of international consensus, and it is difficult to see how it could have gained much ground without the promotion of international organisations (both ecclesial and secular). Yet despite these question marks, Biggar has written a very good defence of just war, and shown other theologians how to engage with difficult moral questions in concrete cases.