HERE are two scenarios we might consider.
I) Sinn Fein are in coalition with Fianna Fail when a faction of the IRA Army Council kills and kidnaps British soldiers and begins long-range rocket attacks on the British mainland from just south of the Irish border. The Tanaiste, Martin Ferris, says that while he regrets the loss of life, there's nothing he can do about it.
Tony Blair asks Bertie Ahern to deal with the lunatics in Co Louth, and Bertie wrings his hands and says his government is too weak, IRA HQ is in a civilian area and he can't politically afford the fallout from collateral damage and will Tony do a deal with the IRA.
As dead bodies pile up in Liverpool, the IRA say they'll kill the soldiers and start on Manchester unless Britain agrees to withdraw from Northern Ireland.
What's the proportionate response?
II) The UVF - fearful of the momentum towards Irish unity - kills and kidnaps Irish soldiers and begins shelling Dundalk. Bertie asks Tony to deal with the lunatics in Belfast, and Tony wrings his hands and says his government is too weak, his army is busy in Iraq, and anyway UVF HQ is in a civilian area and he can't politically afford the fall-out from collateral damage and please will Bertie do a deal with the UVF. As dead bodies pile up in Dundalk, the UVF say they'll kill the soldiers and start on Drogheda unless Dublin agrees to ban SF and accept that Northern Ireland should return to majority rule.
What's the proportionate response?
No, of course these are not direct analogies with what's going on between Hizbollah and Israel. There, things are much worse than in either of the scenarios I've invented, for our terrorists are small beer: neither the IRA nor the UVF would aspire to annihilate the country they're displeased with.
At first, when Israel began shelling Lebanon, I briefly feared they might be reacting disproportionately. Since then I've recovered my wits. Yes, the suffering and the destruction is terrible, but the alternative is worse.
The issue of whether Israel should ever have come into being is not one I'm prepared to argue about. It's there, and the only hope for the Middle East is that Arab states should acknowledge Israel's right to exist, allow it to withdraw from contentious territory knowing it will be safe from heavily-armed crazies and let the world get going on trying to give the poor Palestinians some kind of a life.
But that isn't going to happen. Attacks on Israel are merely a small part of what global Islamism is about. As Michael Gove points out in Celsius 7/7 - his short but brilliant guide to the global threat we all face - as fascism degraded nationalism and communism betrayed socialism, Islamism is a political creed that perverts Islam. Like all totalitarian movements, it aspires through revolution to gain a monopoly on power and create a new civilisation with which it can take over the world.
In addition to Israel, since the early Nineties Islamist jihadi warriors have targeted, inter alia, Indonesia, Pakistan, Qatar, Spain, Russia, Saudi Arabia, Turkey, Indian, Australia, Kenya, Canada, and, of course, the US and the UK. Their intention is to replace existing Muslim countries by a restored Caliphate operating on Taliban lines, which, in due course, will expand to take in the rest of the world. Be they Hizbollah or Hamas or any other off-shoots of the Muslim Brotherhood, they are full of confidence, not least because they consider the West terminally weak. The moral relativism that makes Western opinion-formers reluctant to believe - let alone say - that Western civilisation is infinitely superior to anything Islamic countries offer these days, is a signal to Islamists that we have no heart for battle.
And mostly, they're right. We cave into violence and threats of violence. Spain's most shameful hour was to change government after the Madrid bombings. The cowardice of Europe over the issue of the Danish cartoons should make us all blush. Israel is the only country Islamists know has the will to stand up for herself: no wonder they hate her.
"Of course, the Israeli response is disproportionate!" said an Israeli paratrooper who in civilian life is a lawyer. "If it were proportionate, Israel would have to devote itself to the annihilation of 56 Muslim countries, send suicide bombers to Palestinian cafes and markets, attack mosques worldwide, and conduct a massive and insulting propaganda campaign blaming Muslims for all the ills of the world."
Ireland won't have to suffer either of the scenarios I outlined above. But we will almost certainly have to cope with suicide bombers who will kill Muslims and infidels with equanimity. What will be the proportionate response?