the unselfconscious irony of bioweapons-creating pots gassing about decapitating kettles...,

guardian |  Considered as a broad moral category, what Margalit defines as radical evil is not uncommon. The colonial genocide of the Herero people in German South-West Africa (now Namibia) at the start of the 20th century was implemented against a background of ersatz-scientific racist ideology that denied the humanity of Africans. (The genocide included the use of Hereros as subjects of medical experiments, conducted by doctors some of whom returned to Germany to teach physicians later implicated in experiments on prisoners in Nazi camps.) The institution of slavery in antebellum America and South African apartheid rested on a similar denial. A refusal of moral standing to some of those they rule is a feature of societies of widely different varieties in many times and places. In one form or another, denying the shared humanity of others seems to be a universal human trait.

Describing Isis’s behaviour as “psychopathic”, as David Cameron has done, represents the group as being more humanly aberrant than the record allows. Aside from the fact that it publicises them on the internet, Isis’s atrocities are not greatly different from those that have been committed in many other situations of acute conflict. To cite only a few of the more recent examples, murder of hostages, mass killings and systematic rape have been used as methods of warfare in the former Yugoslavia, Chechnya, Rwanda, and the Congo.

A campaign of mass murder is never simply an expression of psychopathic aggression. In the case of Isis, the ideology of Wahhabism has played an important role. Ever since the 1920s, the rulers of the Saudi kingdom have promoted this 18th-century brand of highly repressive and exclusionary Sunni Islam as part of the project of legitimating the Saudi state. More recently, Saudi sponsorship of Wahhabi ideology has been a response to the threat posed by the rise of Shia Iran. If the ungoverned space in which Isis operates has been created by the west’s exercises in regime change, the group’s advances are also a byproduct of the struggle for hegemony between Iran and the Saudis. In such conditions of intense geopolitical rivalry there can be no effective government in Iraq, no end to the Syrian civil war and no meaningful regional coalition against the self-styled caliphate.

But the rise of Isis is also part of a war of religion. Nothing is more commonplace than the assertion that religion is a tool of power, which ruling elites use to control the people. No doubt that’s often true. But a contrary view is also true: politics may be a continuation of religion by other means. In Europe religion was a primary force in politics for many centuries. When religion seemed to be in retreat, it renewed itself in political creeds – Jacobinism, nationalism and varieties of totalitarianism – that were partly religious in nature. Something similar is happening in the Middle East. Fuelled by movements that combine radical fundamentalism with elements borrowed from secular ideologies such as Leninism and fascism, conflict between Shia and Sunni communities looks set to continue for generations to come. Even if Isis is defeated, it will not be the last movement of its kind. Along with war, religion is not declining, but continuously mutating into hybrid forms.

Western intervention in the Middle East has been guided by a view of the world that itself has some of the functions of religion. There is no factual basis for thinking that something like the democratic nation-state provides a model on which the region could be remade. States of this kind emerged in modern Europe, after much bloodshed, but their future is far from assured and they are not the goal or end-point of modern political development. From an empirical viewpoint, any endpoint can only be an act of faith. All that can be observed is a succession of political experiments whose outcomes are highly contingent. Launched in circumstances in which states constructed under the aegis of western colonialism have broken down under the impact of more recent western intervention, the gruesome tyranny established by Isis will go down in history as one of these experiments.

The weakness of faith-based liberalism is that it contains nothing that helps in the choices that must be made between different kinds and degrees of evil. Given the west’s role in bringing about the anarchy in which the Yazidis, the Kurds and other communities face a deadly threat, non-intervention is a morally compromised option. If sufficient resources are available – something that cannot be taken for granted – military action may be justified. But it is hard to see how there can be lasting peace in territories where there is no functioning state. Our leaders have helped create a situation that their view of the world claims cannot exist: an intractable conflict in which there are no good outcomes.