So what makes a war just? Based on the idea that individuals have a right of self-defence, the theory was developed in response to Christianity’s problems with always turning the other cheek. It proposes one set of conditions that apply to going to war (ius ad bellum); and another to the conduct of war (ius in bello) ...I am really rusty on the topic, but I have never seen the idea that the sole criterion for a just war was self-defence. This could be associated with libertarian and individualist thought, with its emphasis on negative liberty and non-coercion, but not the just war tradition. Brecher is right to say the the doctrine originated as a way of defining the circumstances in which Christians could partake in war. And, more generally, it has developed as a critique of absolute pacifism, arguing that in some circumstances the undoubted evils of war are outweighed by the benefits it can bring. However, surely it is about advancing justice rather than simply defending against aggression, even if the two are sometimes contiguous.
...the only war that can be just is a purely defensive one fought against the combatants of an aggressor and using minimal force.
When doubts are raised like this I always find it useful to look at the core texts, so I turned to the writings of Thomas Aquinas, one of the major sources of classical Just War Theory. In the Summa Theologica he wrote the following (and if you want to skip reading it, it says that a just war boils down to three things; right authority, right cause and right intent).
In order for a war to be just, three things are necessary. First, the authority of the sovereign by whose command the war is to be waged. For it is not the business of a private individual to declare war, because he can seek for redress of his rights from the tribunal of his superior. Moreover it is not the business of a private individual to summon together the people, which has to be done in wartime. And as the care of the common weal is committed to those who are in authority, it is their business to watch over the common weal of the city, kingdom or province subject to them. And just as it is lawful for them to have recourse to the sword in defending that common weal against internal disturbances, when they punish evil-doers, according to the words of the Apostle (Rm. 13:4): "He beareth not the sword in vain: for he is God's minister, an avenger to execute wrath upon him that doth evil"; so too, it is their business to have recourse to the sword of war in defending the common weal against external enemies. Hence it is said to those who are in authority (Ps. 81:4): "Rescue the poor: and deliver the needy out of the hand of the sinner"; and for this reason Augustine says (Contra Faust. xxii, 75): "The natural order conducive to peace among mortals demands that the power to declare and counsel war should be in the hands of those who hold the supreme authority."So, according to the classical theory, a just cause for war is not simply self-defence but "one that avenges wrongs, when a nation or state has to be punished, for refusing to make amends for the wrongs inflicted by its subjects, or to restore what it has seized unjustly". In other words, aggressive war can be waged to rectify wrongs. A just war is a conflict between justice and injustice, between good and evil.
Secondly, a just cause is required, namely that those who are attacked, should be attacked because they deserve it on account of some fault. Wherefore Augustine says (Questions. in Hept., qu. x, super Jos.): "A just war is wont to be described as one that avenges wrongs, when a nation or state has to be punished, for refusing to make amends for the wrongs inflicted by its subjects, or to restore what it has seized unjustly."Thirdly, it is necessary that the belligerents should have a rightful intention, so that they intend the advancement of good, or the avoidance of evil. Hence Augustine says (De Verb. Dom. [*The words quoted are to be found not in St. Augustine's works, but Can. Apud. Caus. xxiii, qu. 1]): "True religion looks upon as peaceful those wars that are waged not for motives of aggrandizement, or cruelty, but with the object of securing peace, of punishing evil-doers, and of uplifting the good." For it may happen that the war is declared by the legitimate authority, and for a just cause, and yet be rendered unlawful through a wicked intention. Hence Augustine says (Contra Faust. xxii, 74): "The passion for inflicting harm, the cruel thirst for vengeance, an unpacific and relentless spirit, the fever of revolt, the lust of power, and such like things, all these are rightly condemned in war."
By restricting the notion of a just war to one waged as self-defence, regardless of what is being defended and who is attacking, the concept becomes divorced from the very thing it is supposed to uphold, justice. As a result, Brecher creates a number of problems for himself. Some are surely errors. He views Israel's 1967 war as the only just war it has fought as it was a defensive war (it was a pre-emptive strike by Israel) whereas he implies that the war of 1973 (which he describes as an attack on Israel's Arab enemies) was unjust despite the fact that the war was launched as a surprise attack on Israel by Egypt and Syria. Others arise from contentious interpretations. However, the strangest is this:
...it follows from the central characteristic of a just war -- that it can be only defensive – that there can be no such thing as a just war. World War II, for instance, the least controversial of any war with a claim to being just, was not a just war. Only the war fought by the Allies was just; the war fought by the Nazis and their allies was clearly unjust. For only “the Allies’ war” was a defensive one; “the Nazis’ war” was aggressive. To the extent that any and every war is at once aggressive and defensive, “the war itself”, so to speak, cannot be just.Eh? Surely a just war is one where one of the protagonists is confronting injustice, not one that has justice on both sides, an obvious absurdity. It is a theory that identifies whether one side to a conflict can be supported against the other, so this hair splitting misses the point. It renders the concept meaningless. So why is he arguing the case? Well, it seems that he has some polemical intent.
Even allowing that just war theory allows intervention on behalf of innocent others, and not just in literal self-defence, there is no post-1945 equivalent of “the Allied World War II”. Every war fought by “the West” has been aggressive; none has been a purely defensive response to attack. Even if one regards the 2001 attack on the World Trade Centre and the Pentagon as an act of war – itself a highly controversial claim, cynically insisted upon by the United States government precisely in order to be able to claim (however unwarrantedly) that its so-called war on terror was a just war – the West’s response cannot be justified by just war theory. For retaliation is one thing, defence another ...Ah. "Cynically", "controversial", "unwarrantedly", "so-called"; a neat collection of value laden terms that take us into familiar territory, the de-legitimation of all Western action since the Second World War. Rather than using theory to inform the debate about the specific virtues or iniquities of each individual case, the article uses it to make a blanket condemnation of all of them. And Just War Theory was developed as a tool to help us make difficult judgements about conflicts, not to avoid them.