<preform>Faith & Reason: Bush and Blunkett could just be right about Guantanamo</preform>

Apply the theory of 'just war' to the detention of terrorist suspects and the results are surprising

When George Bush first announced the "war on terror" there were many who branded it a nonsense concept, for you wage war on people, not on an abstract. It was tempting to dismiss the phrase as the latest example of White House rhetoric - half- biblical in its sonority, and half-advertising slogan in its snappiness - from the school that brought you "the empire of evil" and "one small step for mankind".

When George Bush first announced the "war on terror" there were many who branded it a nonsense concept, for you wage war on people, not on an abstract. It was tempting to dismiss the phrase as the latest example of White House rhetoric - half- biblical in its sonority, and half-advertising slogan in its snappiness - from the school that brought you "the empire of evil" and "one small step for mankind".

But the camp at Guantanamo has shown there was more to it than that. War is a time when normal conventions are suspended. Discussion and diplomacy give way to violence. One definition of war, beyond the obvious one about armed hostilities, is a time in which international law is suspended.

Few would disagree that this is what has happened in Guantanamo. More than 600 individuals have been detained there for more than two years, without charge, without access to lawyers, threatened with trials - if they come - before a military tribunal at which evidence gathered by intelligence services won't be disclosed.

The civil liberties arguments against this seem obvious. As do the theological ones. Injustice is a greater evil than war, said St Augustine, who first formulated the "just war" theory. But as the bombs in Madrid so gruesomely remind us, modern terrorism - with the technology to kill in large numbers - adds complexity, not simply scale, to the old arguments about the balance between democratic values and effective response to violence.

This is not to embrace the Manichaean view that war is of its nature irrational and that therefore "anything goes". The notion of a "just war" insists that war must have its own set of rules and ethical constraints. The question is, how much do circumstances alter that morality?

The Geneva Convention governs how prisoners of war should be treated. Yet it was drafted in a different world where enemies were other nations, combatants were from armies with recognised chains of command, and prisoners could be identified by their dog-tags. Today's enemy is a religio-political ideology, its combatants are united by a shared worldview rather than a command structure, and some of those detained in Guantanamo operate under as many as 12 aliases. So how do the principles of the just war now apply?

Augustine declared that to be licit war must, first, be declared by a competent legal authority and, secondly, there must be a just cause. To this Aquinas added that there must be "right intention" behind the war, that force used must be proportional and that war should prevent more suffering than it causes. Later theologians added three more conditions: that war must be fought by "proper means", that it must always be a "last resort" and that there must be a realistic chance of success.

Apply these to Guantanamo and the result is not clear-cut. Events like the bombs in Madrid give a prima facie justification to arguments that - when it comes to "just cause" and "right intention", to reactions that prevent more suffering than they cause, to "last resort" and "realistic chance of success" - the balance may lie with those who advocate the continued detention of those the US insists are the "hardest of the hard core" of al-Qa'ida terrorist suspects. There are even grounds to argue that the response is "proportional" and employs "proper means".

Ask "has the US lawful authority?" and you come back to the controversial issue of whether the war was lawful. A nation state, in the past, was always considered a sufficiently competent and legal authority; the question of whether the United Nations is a superior authority is unclear thanks to the complexity of international law and the unprincipled politicking which lies behind many Security Council decisions. Nothing clear-cut there.

There are, of course, counter-indicators. Messrs Bush and Blunkett are on dodgy ground in their implicit insistence that only those charged with preserving the public good are competent and legitimate judges of what that public good may be. The danger of self- referential morality is obvious, as is that of locating evil only outside ourselves, in terrorists who refuse to share our codes of honour and rational political interest. Definitions of terrorism are notoriously slippery. We might speak of the random use of indiscriminate lethal violence to achieve political or military objectives through terrorising people. If so, might not the "shock and awe" elements of the war on Iraq fall into such a category? Then there is the argument that considerations of the common good go beyond the protection of the majority and make the rights of the minority a central touchstone of political virtue.

Even so, what all this adds up to is that, when it comes to responding to terrorism, it is by no means clear that the ethical boundaries lie where liberals generally suppose them to.