An event as savage, theatrical and unexpected as the attack on the World Trade Centre has inevitably generated a deep sense of fear. The failure of anyone to claim responsibility for the assault; the fact that (despite the targeting of Osama Bin Laden) nobody really knows who was responsible for organising and financing the action; and the possibility that other terrorist cells may still be at large have all exacerbated that sense of fear.
Yet the apocalyptic terms in which politicians and commentators have responded to the events of 11 September speaks of a fear much more profound than simply a natural reaction to a terrible terrorist attack. 'It has become terrifying clear how close the "Barbarians" are, perhaps in reality always have been', warns the writer (and New Yorker) Sasha Abransky. The destruction of lower Manhattan revealed 'a symbol of our age can be destroyed in a moment, much as the fierce greatness of Rome was overrun by hordes lacking science, literature, art, but fuelled by a fanatical hatred of an urban, cosmopolitan, commercial culture and civilisation far grander than their own.'
Freedom is under attack, runs the mantra. Civilisation is under threat. The Barbarians are not simply at the gates, but inside them too, terrorists with bagfuls of nuclear material, or deadly toxins, just waiting to strike. As George Bush warned a gathering of American clergymen at the White House: 'Another crisis could hit us much more terrible than this one - biological, chemical or plutonium.' The World Health Organisation warns people 'to take the risk of biological warfare seriously and recognise that it might be easier than the use of other forms of potential terrorist warfare.'
Inevitably, such warnings have generated a sense of panic among the public. Stores run out of gas masks, there is a stampede to buy nuclear shelters and the chatter among parents waiting for their children at the school gates is about how to protect against anthrax or smallpox. 'No more sense of security in skyscrapers or airplanes; no more carefree days at the Super Bowl; no more driving on a bridge or through a tunnel without a frisson of fear that the truck ahead may be driven by a suicidal maniac', as journalist William Safire summed up the mood in the New York Times.
'The world will never be the same again', is the constant refrain. And perhaps it won't - but not because of a terrorist attack in Manhattan. Rather, if the world is changing, it is changing because of our perceptions of what that attack has done to our lives. There has been much talk over the past three weeks about the need for a proportionate response to the assault. A good place to start would be by injecting some proportionality into our understanding of it. Over the past century the world has faced two world wars, a Cold War, Nazism, and the Holocaust. There were times when the Barbarians did indeed appear to be at the gates. But the world survived. So, why do we feel so threatened by a single criminal act, albeit a particularly monstrous one?
Terrorism is not new, even on the scale that was visited on lower Manhattan (though, from the firebombing of Dresden, through the devastation of Hiroshima and Nagasaki to the carpet-bombing of Cambodia, terror on this scale has usually been the work of those nations that are now leading the fight for civilisation). What was new about the attacks was their arbitrary, nihilistic brutality. What was also new was the way that they exposed vulnerabilities, not just of the USA, and not just in a physical sense. The hijacked planes tore into the fabric not simply of the Pentagon and the Twin Towers, but of the confidence and self-belief of Western societies. And into that gaping hole have marched a whole host of demons. 'If a flight full of commuters can be turned into a missile of war', observed the New York Times, 'then everything is dangerous'. It is in giving focus to this sense of dread, to the belief that even the ordinary may be hazardous, that the attacks may have had their most devastating impact.
Take, for example, the idea that around every corner might lurk a terrorist armed with a weapon of mass destruction. It's an idea that inevitably fosters a climate of distrust and paranoia, atomising society further and undermining possibilities of social action. It facilitates attacks on civil liberties, from the introduction ID cards, to tighter controls on immigration and asylum seekers, to new police powers to hold 'terrorists' indefinitely - none of which will have much impact on the prosecution of terror, but all of which will curtail the freedoms of ordinary citizens. And it eases the way to Western intervention abroad - think of how fear of Saddam's 'weapons of mass destruction' has been manipulated to help maintain support for economic sanctions against, and continued bombings of, the Iraqi people.
Of all the imagined weapons in the terrorist arsenal, biological warfare appears the most terrifying: a silent, invisible killer, gnawing away at a population from the inside, it is a perfect metaphor for Western vulnerabilities. Such fear of bioterrorism has been accentuated by the peculiar relationship of contemporary Western cultures to biotechnology. There has built up, over the past decade, considerable unease about technologies such as cloning and the genetic modification of organisms because they seem to corrupt the relationship between Man and nature by dissolving the boundaries that appear to maintain order in the natural world. In an age in which social and moral boundaries appear so fluid, our social anxieties often get relocated into the natural world, creating apprehension of what might happen if we begin to tinker with nature.
This is one of the reasons for the shift in focus, over past decade and a half, from the threat of nuclear to that of biological terrorism. This shift is an expression of changes not in terrorist strategy - terrorist groups no more possess biological weapons now than they possessed nuclear warheads a decade ago - but in social anxieties. After the break-up of the Soviet Union, what politicians and strategists feared most was that the chaos that prevailed in Eastern Europe and the Third World would spill over into the West. This gave rise to the image of the fanatic with a nuclear bomb in a suitcase, built with the expertise of unemployed Soviet physicists. Today Western values and freedoms appear under threat as much from the inside as from the outside, a sense strengthened by the knowledge that the hijackers on 11 September were not stereotypical Islamic fundamentalists, but Western educated, highly integrated, fluent in English and German, and given to vodka-binges at the weekend. So now we imagine that same fanatic but with a bagful of bio-engineered germs, corrupting society from within.
According to the American writer and anti-biotechnology campaigner Jeremy Rifkin, 'All you need is a beer fermenter, a protein based culture, plastic clothing and a gas mask' to ensure 'bacteria and viruses raining down from the sky over populated areas, infecting and killing millions of people.' Wilder still is a claim by George Poste, chairman of the US Defence Science Board's panel on bioterrorism. The Defence Science Board is a federal advisory committee established to provide independent advice to the secretary of defence. According to Poste, terrorists may be creating genetically modified organisms that are integrated into a target's genome but which only become activated 'when you presume that the political ideology of your opponent has become sufficiently offensive.'
In reality, however, bioweapons are both difficult to produce and their effects are not as devastating as many imagine. Take, for instance, anthrax, which the US Defence Department describes as '100 000 times more deadly than the deadliest chemical weapon'. The World Health Organisation estimates that 50 kilos of dry anthrax used against a city of one million inhabitants would kill 36,000 people and incapacitate another 54,000.
Anthrax is a rod-like bacterium that normally affects grazing animals such as cows, goats and deer that ingest bacterial spores naturally occurring in the soil. It rarely infects humans, but the illness can be contracted in three ways: through bacteria infecting wounds, through eating infected meat, and by inhaling sufficient numbers of anthrax spores. For many years anthrax was called 'woolsorters' disease because workers at woollen mills were most at risk from naturally occurring spores. The danger, however, was relatively small. A 1960 study in a Pennsylvania goat hair mill showed that workers inhaled more than 500 spores per 8-hour shift, and yet there were no cases of illness among the workers. Indeed, in the whole of USA only 18 cases were reported between 1900 and 1978.
The US Defence department estimates that an individual must inhale between 10 000 and 50 000 spores for the disease to take hold. This will only happen if huge numbers of spores are dispersed in the air and kept there (the natural tendency of anthrax spores is to drift to the ground in the absence of wind). Technically this is extremely difficult to accomplish.
First, anthrax spores need to be converted into a powder. Only the USA and the Soviet Union, both of whom expended millions of dollars in developing bioweapons during the Cold War, have refined the means to do this. Iraq was supposed to have a well-developed anthrax programme. UN weapons inspectors, however, only discovered anthrax in liquid form, which, according to one expert 'is almost as safe as candy'.
Having turned anthrax into powder, a potential terrorist would have to find a way of dispersing it in the air. Again, this is much more difficult than might be imagined. There was much alarm when the FBI revealed that some of the hijackers involved in the World Trade Centre attacks had previously made enquiries about crop-dusting planes. According to Barbara Rosenberg, director of the Federation of American Scientists' chemical and biological weapons programme, 'a crop duster would be very useful for a chemical and biological attack - if you wanted to attack crops.' But it would not be that useful in attacking humans. To get spores to lodge deeply enough in the human lung to cause damage, they must be extremely small - less than 10 microns in size. Crop dusters are fitted with much larger dispensers meant for insects and plants. It would certainly be possible to modify them, but such modifications would require considerable expertise. 'You can't go down to store and buy one off the shelf', observes Rosenberg.
There are similar problems with another imagined terrorist favourite - smallpox. Smallpox is a virus that can cause bleeding and lesions all over the body, and used to devastate large parts of both the developed and the developing world. Unlike anthrax it is highly contagious, but it is also very fragile and difficult to manipulate. It is also almost impossible to obtain. The virus was officially declared eradicated by the WHO in 1979. Only two laboratories in the world still possess supplies of live smallpox virus - the Centre for Disease Control and Prevention in Atlanta and the high-security Russian installation at Novosibirsk. Neither is likely to provide handouts for terrorists.
According to the FBI, there has only been one known case of bioterrorism in the USA. It involved the Rajneeshee, a religious cult, who had established a large commune in Wasco County, a rural area east of Portland, Oregon. In 1984 the cult decided to take political control of the county by manipulating the results of elections in November of that year. They planned to bus homeless people into their commune and register them as voters, while at the same time make opposing voters sick by infecting them with salmonella. Cult members contaminated food in ten salad bars with the bacterium Salmonella typhimurium which causes diarrhoea. 751 people became infected, though none was seriously ill. Two members of the cult were eventually convicted for their involvement in the plot. The election results remained unaffected.
The 751 people infected by the Rajneeshee, in a plot more comic than tragic, are the only known victims of bioterrorism. The only other group known to have attempted to use biological agents is the Aum Shinrikyo cult in Japan. Despite spending millions of dollars, and having a large number of biologists on its payroll, the attempts proved to be as bizarre and as unsuccessful as in the Rajneeshee case. In April 1990 the group tried to covert a car to spread botulism through the engine's exhaust. Three years later it attempted to spread anthrax by using a sprayer system on the roof of a building in eastern Tokyo. Neither incident resulted in a single casualty.
In the end the group abandoned its plans for biological warfare and turned to chemical weapons instead. In March 1995 it released sarin, a nerve toxin, into the Tokyo subway. The group was estimated to have spent $10m dollars preparing this attack. Thankfully just 12 people died. This still remains the most devastating non-military chemical attack ever.
All of which is why, according to a report produced for the Washington-based National Defence University Strategic Forum on The Threat of Bioterrorism, 'few terrorists have demonstrated real interest in bioterrorism and fewer still have made an attempt to acquire biological agents.' Even if terrorists do develop a bioweapon it is unlikely to be as deadly as we imagine it will be. As the attack on the World Trade Centre revealed, terrorists can be just as devastating using low-tech methods. The fear of bioterrorism is likely to be far more debilitating than bioterrorism itself.
So why does the terrorist with a suitcase full of plague or anthrax remain such as potent image? Partly because he speaks to so many of our contemporary anxieties, from the dangers of messing with nature to the sense of the fragility of Western values. At the same time the image presents the authorities with a bogeyman to trump all bogeymen. Compared to traditional bogeys, such as the mugger or the crack dealer or the paedophile, the faceless terrorist who might yet be your neighbour is a far more sinister figure. Like all bogeymen, it is an image rooted in reality - you only have to look at the Manhattan skyline to recognise that. But, like all bogeymen, it is also a mythical creation, the aim of which is to make palatable draconian and illiberal measures that might otherwise have been unconscionable. And so much more sinister is this particular bogeyman that one can wheel him out to justify policies that are that much more draconian and illiberal, from the demolition of civil liberties at home to the prosecution of war abroad.
'No passion', Edmund Burke once wrote, 'so effectively robs the mind of all its powers of acting and reasoning as fear.' Rarely has this been more true than it is today. Before fear drives out all reason, we need to take a measured, rational, proportionate view of what actually happened on 11 September.