At 10.57 on Sunday morning, just minutes before the UK was due to fall silent to honour its war dead, a taxi pulled up outside a hospital in Liverpool. It had hardly stopped before it exploded in a cloud of white smoke and flame. 

The driver, David Perry, miraculously still alive, managed to get out of the vehicle where he was helped by bystanders. Others tried to douse the rapidly-spreading flames but his passenger, 32-year-old Emad al-Swealmeen, was already dead; killed by his own bomb.

There is still much that we do not know about the attack, right down to its intended target. Some reports have suggested that al-Swealmeen's real target was Liverpool CathedralBritain's largest cathedral and religious building and the eighth largest church in the world. It was constructed between 1904 and 1978., where 2,000 people had gathered for a Remembrance service. Others think he might have been imitating a recent Islamic StateA terrorist organisation that captured whole swathes of territory in Iraq and Syria in 2014, and launched a series of attacks in Europe and North America. It is also known as ISIS or ISIL. attack on a maternity ward in Kabul.

Al-Swealmeen's motives are mysterious. The attack resembles those carried out by the Islamic State. The explosive he used, TATPA kind of organic explosive commonly used in improvised explosive devices (IEDs). It is favoured by terrorists because it is easy to make, but it is extremely volatile and often goes off accidentally., was the weapon of choice in the 2015 Paris attacksA set of coordinated attacks in Paris focusing on the Stade de France and the Bataclan theatre. 130 people were killed and 416 injured. and the Manchester Arena bombingIn 2017, a bomb was set off in Manchester Arena at the end of an Ariana Grande concert. 23 people died and more than 1,000 were injured. of 2017. 

But al-Swealmeen converted to Christianity, in the cathedral some claim he was targeting, before spending eight months living with a Christian couple.

That is why some have turned to al-Swealmeen's mental health for an explanation of his actions. In 2014, he was sectionedThe term used when someone is detained under the provisions of the Mental Health Act, which allows people to be treated without their agreement if they need urgent treatment or are at risk of harming themselves or others. under the Mental Health Act after brandishing a knife in central Liverpool, and spent several months in hospital.

Many think that terrorism in general can be explained through mental illness. They point out that in almost all high-profile terrorist attacks, it has turned out afterwards that the perpetrator was suffering from mental health problems.

They argue that while no specific mental health disorder has been linked with terrorist activity, mental illness should be treated as a factor in causing people to commit terrorist violence, especially trauma and PTSDA mental health disorder that is triggered by experiencing or witnessing a terrifying event..

But others are not so sure. They point out that the evidence is by no means clear. One 2017 study of 76 terrorists who carried out attacks in the West found 27.6% had a history of psychological instability, which is similar to the level in the general population.

Those who suffer from mental illness are far more likely to be the victims of violence than to be violent themselves. Some fear that calling terrorism a form of mental illness could further stigmatise those with mental health problems.

Instead, they suggest, we should look at how al-Swealmeen fell through the cracks of society. Shortly before he was sectioned, his application for asylum status was rejected. By 2017 he was out of money. Shortly before the attack he was living in a hostel for asylum seekers.

They argue that al-Swealmeen's mental illness was a consequence of his despair and frustration at the way society had treated him. So terrorism is not a symptom of mental illness, but of rage, resentment and alienation.

Yes, say some. Emad al-Sweelmeen is the latest in a long line of terrorists in the West who had been suffering from severe mental health problems. This does not mean that people who are mentally ill are likely to be violent, but there can be no doubt that violence is often caused by mental illness.

No, say others. There are a whole range of factors that can lead people to commit acts of terrorism, ranging from extremist beliefs to online radicalisation. Mental illness is just one of these factors. Terrorism is complex, with many causes, and we should not reduce it to just one of these.