When terrorists strike, we fall back on the conventions.

Consolation to the bereaved, but what can you really say when 22 souls have been wiped out without meaning?

Anger at the perpetrators, but what can you do against anonymous suicide bombers prepared to die in order to kill?

Respect to the emergency services, who never flinch in the face of danger, but know they’re only heroes for a day. Tomorrow they'll be back to being plain old “public service workers”.

Ok – we respond with cliches, but that doesn't make them any less worth saying. Just because terrorism is now part of urban life, an unnatural hazard of globalisation, that doesn't mean we should lapse into cynicism or apathy. 

There's work to do. Politics has gone on hold for the duration, but as with the death of the Labour MP, Jo Cox, all of us are required to address our prejudices and try to understand how antique ideologies of hate – white racism, Islamic terrorism – have emerged from the shadows and spread their viral cancer through new media.

The police and the security services will learn much from this bombing and will do everything in their power to track down the perpetrators.

But when the principal author of this atrocity is already among the dead this is of limited use.

You can't punish suicide bombers for their crime, though of course you can attack the network that supports them.

You have to attack their ideology at source: drain the swamp of delusion that cultivates suicide bombers.

Never accord these cruel idiots the dignity or respect of being addressed as enemies.

US President Donald Trump talks of “utterly destroying this evil ideology”, assuming that Islamic State is responsible for the Manchester bombing. But we should avoid the temptation to hurl a few more Moab bombs on the Middle East or ban Muslims at the borders.

Lethal force may of course be necessary, if it is possible to destroy the people who plan terrorist bombing attacks. But as we have seen in recent attacks – Bataclan in Paris, the Westminster knife attacker – it's not always easy to know who to kill. Very often it is individuals acting on their own initiative.

The Manchester bombing will no doubt lead to calls for immigration to be halted, as has been attempted chaotically in America, to exclude certain religious groups.

But since terrorists are as likely as not to be home grown, trying to assign collective blame in this way is counter productive. It simply confirms the terrorist in their delusion that there is a clash of civilisations between the Christian and Muslim worlds.

There isn't. Full stop.

So, while we fall back on cliches let’s also avoid simplistic solutions. We have to accept that there are small numbers of alienated groups mostly, but not exclusively, in the Middle East who seek to kill people here indiscriminately.

But the cowardice of their actions belies their impotence. People who attack teenagers at a pop concert scarcely deserve to be called terrorists, let alone fighters for a cause.

They are the evil product of peculiar circumstances and need to be dealt with, as we would dangerous beasts. But they can only succeed if we follow their script, over-react and retaliate in kind against minorities.

Manchester has united in defiance of this assault and that spirit confirms that these murderers have already failed.