War, it seems reasonable to suggest (and Nicholas Fotion does), poses at least two unique problems to the armchair ethicist. The first is related to scale; the second to conduct.

Firstly, since wars are intrinsically violent and invariably lead to large-scale loss of life, even at the best of times, they are ethically undesirable. That is to say, the consequences of needless wars are a greater moral crime than the consequences of most unjustified ethical undertakings. As far as possible, therefore, war should be avoided. Secondly, wars are distinguished from other actions in that they take place over an extended period of time – that is, they have duration. If Smith punches Patel, we may examine the rectitude of his doing so before and after the event, and we have only one act to examine. But if Smith’s country invades and occupies that of Patel, we may examine the rectitude of his doing so before, after, and also during the invasion (and the war that facilitates it). We speak of being in a state of war in a way we do not speak of being in a state of punching (unless we are boxing coaches).

To answer these special needs, philosophers over millennia have developed a number of theories to answer the question of when war should be undertaken and, once begun, how it should be conducted. In the West, the distilled version of these theories has reached modern philosophy as Just War Theory (JWT).

Fotion’s approach to JWT in this brief but cogent book risks reducing JWT to little more than a checklist, so that decisions about whether or not to risk mass death become a kind of box-ticking exercise. This approach has the merit of being logical, mechanical even, but stops Fotion from really sinking his weapons into the ethical conundrums he proposes, so that the book poses more questions than it answers. It is divided into three parts: first, the checklist; second, some practical applications of it to previous wars; and third, an attempt to re-mould JWT for modern wars, which are increasingly waged between states and non-state actors – that is, against terrorism. The six-point checklist consists of just cause, last resort, proportionality, likelihood of success, right intentions, and legitimate authority. These are largely self-explanatory, but, again, they are worth defining, if only to show their potential inadequacy.

A just cause consists of imminent, present, or recent acts of aggression against a country, or humanitarian catastrophe. A just cause of war (jus ad bellum) is to be distinguished from justice during a war (jus in bello). Last resort is, obviously, a delay mechanism. Proportionality is a costs versus benefits analysis. Likelihood of success says don’t fight wars you know you’re going to lose. Right intentions explore whether war is being waged with appropriate outcomes in mind. Legitimate authority – by far the most contentious point, especially in the context of a war on terror – tells warmongers to keep law on their side. See how simple it is? That’s precisely the problem. There is something a little naive about reducing war to these six criteria. Analysing the rectitude of a war according to them will have its merits, but ultimately wars may be fought for reasons that transcend the limits of this checklist.

Fotion provides historical examples to show the efficacy of his method, before updating it in two important ways. He shows that in the wars against Germany, Korea and Iraq (the first time), the case for war was clear because of aggressive provocation in each case. Wars against Serbia (in 1914), Russia, Kosovo and Iraq are harder because the aggressor was not always answerable to the state, or there was no clear humanitarian case for launching war.

Whether or not the case is clear, warmongers can examine whether there might be multiple rather than single reasons for going to war against another country. Iraq (2003) provides a case in point: it may not have launched an attack on the West, but a combination of factors may have made attacking Iraq justified. This was precisely the reasoning of General Sir Mike Jackson, formerly the head of the British Army, on the BBC’s Newsnight recently. Iraq did not pose an existential threat to the West, but it was in defiance of several UN sanctions, it was thought to be affiliated to international Islamist terrorism, Saddam Hussein had conducted a pogrom in his back garden, and may have had weapons of mass destruction. The trouble with this kind of justification for war (as Fotion points out) is that, aside from smacking of desperation, it fails to trump another one of Fotion’s self-imposed obstacles to just war, namely last resort. The inflexibility of the checklist makes multiple reasoning (as opposed to single reasoning) interesting but ultimately obsolete. In the case of Iraq, it still wouldn’t justify the invasion and subsequent occupation – a point Fotion concedes – because the warmongers could always have given inspectors ‘one final chance’.

The second way in which Fotion updates JWT to cope with his historical examples does illuminate some of the ethical complexities of modern warfare. In an essay published in April 1991 in La Rivista dei libri called ‘Reflections on War’, the Italian writer Umberto Eco was one of the first Western intellectuals to grapple with the distinctive feature of modern warfare, namely its creating opposition between states and non-state actors. The rise of terrorism, Eco argued, has created a ‘neoconnectionist’ system of warfare. No longer is war like chess, where one side moves and waits for the other to respond, where strategy is both a single and two dozen moves away.

Fotion copes with this by inventing two subsidiaries of JWT – JWT-R for ‘regular’ wars between states, and JWT-I for irregular wars between states and non-state actors. ‘The overarching difference’, he says, ‘is that parts of JWT-I are asymmetrical’. This asymmetry means that different rules apply for the states on the one hand and the terrorists on the other. Terrorists, who tend to have grievances and consider themselves victims of oppression, usually have highly promiscuous definitions of ‘provocation’. They take small provocation very seriously. They consider the legitimacy of their authority to be concomitant not with the law but with the level of their suffering. They don’t give a hoot for proportionality in response: if anything, inverse proportionality appeals to them. Crucially, they measure success not only by the level of carnage they achieve but by the fear they instil. That is why terrorism, though it can harm and surprise a society, can never define it: only the response to terrorism speaks of that society’s values.

Fotion’s argument experiences an internal battle. Throughout this book, a consequential, utilitarian analysis competes with a deontological one, wherein customs become sacrosanct, duty is exalted, and the suffering or murder of innocents is relegated to secondary relevance behind the need to uphold law. There are times, for example, when breaking the law might be justified, in order to save lives. When the Kosovo War was fought in 1999, this was the reasoning employed by the West. Part of Fotion’s argument suggests this is defensible: after all, a humanitarian disaster can count as a just cause. But another part says this is indefensible: the lack of legitimate authority, by which is meant legal backing, means Kosovo should not have been bombed, regardless of Milosevic’s tyranny.

What, then, are we to do when we cannot get legitimate authority for wars that are compelled by justice?  Are we to abandon them, and disregard the suffering of innocents?  Fotion is far from clear, and one suspects that is because the straitjacket into which his checklist constricts him is impossible to escape. Intellectual rigidity and morality are not comfortable bedfellows. The really interesting questions, then, include these: what makes authority legitimate?  Is it consent, and if so, whose consent?  Do democracies have a better claim to be consensual than autocracies?  The inflexibility of Fotion’s useful but ultimately dissatisfying book prevents a proper analysis of these deeper issues.

There are many wars which could be fought using JWT’s box-ticking exercise, but which ought not to be. Similarly, there are many wars which would not be fought because of JWT’s rigidity, though they ought to be. After all, unforeseen consequences may make a mockery of justice – in which case, justice itself needs to be susceptible to scrutiny, rather than ossified in theoretical tidiness.