As the Second World War was sputtering to a close, Jean-Paul Sartre recalled an encounter with a well-meaning American who believed that war "could be abolished for ever" if only international relations "were in the hands of well-balanced and reasonable men". Sartre, probably shaking his head in weary resignation as he scrawled his words on paper, concluded with a terse statement on the difference between him and his American interlocutor: "I believe in the existence of evil and he does not."
Less than 50 years later, Sartre's observation seemed either mistaken or anachronistic. By the 1980s, Ronald Reagan was peppering his speeches with references to the "evil empire" of the Soviet Union; a 1988 Gallup poll found that 66 per cent of Americans professed belief in the devil, compared with barely 30 per cent in France and other western European countries; and now President George W Bush has announced his determination to fight an "axis of evil". As Barbara Gunnell wrote in the New Statesman of 11 February, "evil is back", and the Americans, with self-righteous indignation, are apparently those leading the charge.
Yet the word "evil" has still to find favour among sceptical members of the intellectual left, who responded to Bush's State of the Union address with outrage and ridicule. The E-word is viewed as the recourse of fearful, Manichaean and altogether unsophisticated minds. Gunnell suggested as much, pointing out how, "in our Godless age", evil is a slippery, vague and antiquated concept: "It is our privilege to live in a scientific age," she wrote, "and - New Age fads notwithstanding - we generally believe in cause and effect, rather than mysterious universal forces."
David Talbot, writing in the online pages of Salon, concurs, lambasting "Bush's black-and-white rhetoric" for failing "to grasp the complexity of the world". Bush's disingenuous misuse of the E-word, with all its hypocrisy and name-calling, constitutes only part of the indictment against him: his critics have also attacked the very use of the E-word itself. The right delights in moral certainties; the left prefers the language of misfortune and tragedy. Intellectual scepticism cautions against adopting a term fraught with such metaphysical connotations. The word "evil" insinuates vulgar bombast and hyperbole; it demands quotation marks before it can pass for tasteful in progressive company, a cloak of irony lest it expose itself for the earnest, unforgiving condemnation that it is.
Is this position of curious detachment the right one? The past 60 years have seen some of the worst atrocities in human history: the extermination camps of Chelmno and Treblinka; the massacres of Vietnam; the killing fields of Cambodia; the frenzied slaughter of the Rwandan genocide; the mass graves in Bosnia and Kosovo; and, last year, the wilful decision to hijack four commercial airliners full of passengers, steering them towards populated landmarks with the intention of annihilating as many civilians as possible with as much spectacle as possible. While these events have suggested a seemingly boundless capacity to inflict harm, evil - both as a concept and as a word - has been slipping into a self-conscious parody of itself.
Intellectual scepticism notwithstanding, American political discourse has always contained allusions or references to the diabolical - from Puritan fears of demonic possession to Joseph McCarthy's anti-communist zealotry and the entry of the "evil empire" into the hawkish lexicon of the cold war. Americans, despite their claims to enlightened innocence, have always been amenable to uncomplicated demagoguery of the fire-and- brimstone kind. Bush's frequent use of the word "evil" simply exploits an American inclination that was born of the country's idealistic beginnings and reinforced by its youth and its isolation. Evil explained all the bad stuff that happened; it was something that existed out there or offshore, in the hostile stranger or the hopeless criminal. The United States is one of the few liberal democracies where capital punishment thrives, reflecting an ethos that holds evil as an aberration, the product of "evildoers" only, and impossible for the ordinary, incorruptible, American soul.
These sanctimonious platitudes have provoked understandable suspicion, especially when the word "evil" is used by social conservatives and religious moralists against quite mundane things. And the right can always be criticised for its refusal to apply the same unforgiving standards of judgement to social issues such as poverty and income inequality. Barely two centuries ago, even the Anglo-American left did not hesitate to adopt the hyperbolic adjectives that we are so self-conscious about today; the poet William Blake referred to "Satanic mills" to evoke the working conditions unleashed by industrialisation, while American abolitionists in the 19th century denounced slavery as "a deep, detestable, damnable evil . . . [that] withers what it touches".
To sensitive and sceptical ears, these words smack of moral absolutism, perhaps the only unforgivable sin in our post- metaphysical age. The contemporary, secular left does not see it as an indictment when others accuse it of approaching morality from a relativist perspective. Rather, it believes that it is a considered response to the fury of reactionary impulses, whether these be religious or political in nature. The inclination to suspend judgement, to appreciate complexities, to look for the structures that impel and constrain human activity: these are all admirable traits upon which intellectuals often like to commend themselves. To them, a lack of such attitudes explains many of the world's tragic events. To take a relativist view is to guard against demonising our enemies in a rush of pathos and resentment; it makes us more empathetic, encouraging us to view even the terrorists of 11 September as just another group of human beings.
Open-minded individuals are often very good at this: doctrinaire moralists are not. Gunnell speaks to this open-mindedness when she points out a preference for "the language of rights and justice" over the word "evil", which simply bristles with mythical connotations and magisterial certainty. In the case of 11 September, Gunnell offers a variation of the "root causes" argument: rather than vilify Osama Bin Laden and his followers as "evildoers" ripe for elimination, we should try to understand "why young Muslim men . . . are prepared to die killing innocent civilians".
Try to understand we should. But suppose, for a moment, we were to come to a point where we amassed all of these "root causes" and then arranged them into a narrative resembling a "logic" behind 11 September; what kind of story would satisfy our craving for "cause and effect"? What kind of structural factors could completely account for the magnitude of the intended carnage? We can try to say that 3,000 office workers were incinerated "because" of American hegemony in the Middle East or Israeli barbarism in Palestine; we can try to say that 800,000 Tutsis were butchered "because" of the legacy of Belgian imperialism; we can try to say that six million Jews were murdered "because" of the Treaty of Versailles, or "because" Hitler was an illegitimate child. All of these factors surely helped to create grievances, and these grievances surely helped to create the events that followed. After a certain point, however, they ceased to contribute anything, as what was to follow exceeded any sense of necessity that characterises the causal relationships we desperately seek.
This dark space - this gap between what would conceivably constitute a necessary response and what could only be considered a horrifying excess - deserves a name.
Human beings push against the limits of the natural world, acting upon them rather than simply reacting to them; we believe that a "meaningful" life entails more than the necessary acts of sleeping and procreating, foraging and eating. In this, we differ from animals who live in response to their environment; when they take the life of another, they do so out of what John Updike calls "a joyless necessity" - for the purposes of survival or because of an evolutionary imperative. Although an animal's behaviour might be deemed ferocious or cruel, it would be difficult to use the word "evil" to describe what it does. Derived from the Old Teutonic ubiloz, meaning "up" or "over", the word "evil" implies something beyond necessity, some sort of excess.
Religious moralists think of this excess as something that comes from without, a satanic impulse that dooms the possessed. Moral relativists also think of it as something that comes from outside; but they see the source as something more worldly and less holy, be it a social structure or an abusive childhood. In other words, ordinary people do extraordinarily horrible things when their constitution compels them to do so; and while the moralists and the relativists may differ in the terms that they use, they share an unwillingness to address the role of individual choice, no matter how constrained or limited that choice might be. Evil - if applied to that dark space between necessity and excess - can only reside within the boundaries of the self. Its source lies in the very thing that makes us human: the impulse to transcend the reality that surrounds us, to abstract from our concrete experience and to free ourselves from necessity. As such, the human capacity for good is inevitably tied to the human capacity for evil: both account for those actions that lie beyond the necessary requirements of everyday survival.
We like to construct stories behind our choices, drawing relationships between events as we search for the elusive "because". Even Hitler managed to convince himself of the inevitable logic behind his actions: "I would prefer not to see anyone suffer, not to harm anyone. But when I realise the species is in danger, then, in my case, sentiment gives way to the coldest reason." Attempting to understand more recent atrocities, we can propose theories, offer formulae and draw logic trees, but we come to a point where the "because" lies with human beings themselves, who decided that the right response to their situation entailed treating other human beings as candidates for annihilation.
Writing in 1945, the philosopher Ernst Cassirer remembered how, when he and his colleagues first heard of the Nazis' "political myths" of a master race, "we found them so absurd and incongruous, so fantastic and ludicrous that we could hardly be prevailed upon to take them seriously". As the war progressed, however, this derision was abandoned as "a great mistake". "The mythical monsters were not entirely destroyed. They were used for the creation of a new universe, and they still survive in this universe." In the 57 years since the end of the Second World War, those "mythical monsters" have seemed far from extinction, or even surrender. Yet as Hannah Arendt reported in her coverage of the Nuremberg trials, the monsters in some cases were not so much mythical as banal. Arendt was amazed to discover how "ordinary" Adolf Eichmann seemed to be; how he had participated in the Holocaust because of his careerist ambition, rather than from any sense of grievance or obsession with grandiose ideals. This dissonance - the disconnection between those acts that "shock the conscience of mankind" and the seemingly deficient stories put forward to explain them - prompted Arendt to conclude with her statement about "the banality of evil". In her earlier work, The Origins of Totalitarianism, Arendt had referred to "radical evil"; now she saw Eichmann as the personification of evil without a "root", an evil which could explain itself only in terms of the system that encouraged it, without any reference to the necessities of the world that existed outside the Nazi machine. This evil was rootless because neither reality nor the system was able to close the circle of logic for Eichmann's behaviour. Closure lay somewhere in the depths of the self, at the very banal, very ordinary, moment of choice.
In Joseph Conrad's Heart of Darkness, Marlow detects what lies behind the horror of Kurtz: "There was nothing either above or below him, and I knew it. He had kicked himself loose of the earth. Confound the man! he had kicked the very earth to pieces . . . I saw the inconceivable mystery of a soul that knew no restraint, no faith, and no fear, yet struggling blindly with itself."
Here is evil stripped bare of all attempts to justify itself. Tearing himself away from the reality that surrounds him, Kurtz lives entirely within that dark space of the soul, a void limited only by its infinite aspirations towards transcendence. He tries to convince Marlow of his reasons for all of "the horror", but in them Marlow can see only a conspicuous lack.
Writing on the subject of evil, Sartre maintained that "knowing its causes does not dispel it, that it is not opposed to Good as a confused idea is to a clear one, that it is not the effect of passions which might be cured, of a fear which might be overcome, of a passing aberration which might be excused, of an ignorance which might be enlightened, that it can in no way be turned, brought back, reduced, and incorporated into idealistic humanism . . . Therefore, in spite of ourselves, we came to this conclusion, which will seem shocking to lofty souls: Evil cannot be redeemed."
His conclusion may seem unforgiving in our post-everything era, but Sartre reminds us that, when confronted with relentless atrocities, the sheer scale of the horror is perhaps explicable, but ultimately inexcusable. How we decide to continue from that moment of recognition is another matter entirely. Recognising, however, that evil exists; that it is part of what constitutes human reality; that its realisation lies at that final moment of choice: all of this is necessary if we are to live in a world where the technological capacity to annihilate each other requires us to make a conscious decision not to.
Jennifer Szalai is an editor for Harper's Magazine in New York