An armoured car guarded the Grand Place in Brussels city centre yesterday as a group of women sat drinking coffee at an outdoor table. A reporter asked one of them what she would do if terrorists started shooting? She said: "Smile. Sit. Drink coffee. Enjoy – even if it is the last."

She is either courageous or daft, depending on your point of view. Crucially, she is able to make her own choice. Like every citizen in Western democracies, she has freedom of thought, belief, action and the right to cast a free vote.

That, after all, is the point of democracy. The various legal systems of western countries have one guiding principle in common. They protect the liberty of the individual.

So, not surprisingly, we react to terrorist outrages as not just attacks on the unfortunate individuals who are killed or wounded but as threats to us all and how we live our lives. Our very identity is under attack.

We rage against the injustice and barbarity of indiscriminate killing on our streets. Why us? What have we done to deserve this?

What indeed? The answer, of course, is that nothing can ever excuse such atrocities. Though I think we would be wise to recognise that moral outrage and a something-tough-must-be-done-quickly political culture too often has unintended and harmful consequences.

Not only can these rob us of the justice of our moral argument, they can make the West appear hypocritical and worse as our bombs accidentally destroy the liberties (and innocent lives) of people in other, poorer countries.

Let me make clear. I’m not necessarily against Britain joining France, America and Russia in bombing Islamic State (IS) in Syria, it’s just that I wish the political debate was more thoughtful and took greater account of these unintended and often bloody consequences.

There was, for example, that dreadful incident in October when coalition bombs hit a Medicins Sans Frontieres hospital in Northern Afghanistan. The death toll reached 22. It included 10 patients – three of them children and 12 MSF staff.

Also last month international observers reported that Russia, our recently- acquired if unreliable ally, had hit four hospitals in Syria within its first two weeks of bombing.

As France committed yesterday to intensify its aerial bombardment of IS, David Cameron stood "shoulder to shoulder" with President Hollande. Our Prime minister said he too wanted to bomb IS in Syria. He sounded very like Blair post 9/11 and in tune with his criticism of Jeremy Corbyn who should, he said, start behaving less like Chamberlain and more like Churchill.

Mr Cameron came across as glib in a situation that requires our actions to be wise and considered. I had more respect for the shadow chancellor’s response. John McDonnell said he supported a free vote in the Commons; a vote taken not along party lines but in the national interest.

We can all feel the sudden pull towards greater military involvement but I wish the rhetoric voiced more concern for the innocent individuals in the areas where we plan to bomb. The talk is all of Raqqa or Syria being an IS stronghold. But what about the civilians the jihadis live among?

Britain, like America and France, take care to avoid collateral civilian deaths in bombing raids or in deploying drone strikes, like the one which killed Jihadi John. But that was also true for the British in Afghanistan.

During eight years of war there, the British paid compensation for 186 civilian deaths and for the damage or destruction of 4,000 Afghan homes. The numbers are small in the context of war – a tribute to the care our troops take. (To put them into context, the Americans report that civilian deaths in Afghanistan exceeded 10,000 in 2014.) However it takes very little to leave a deep wound where the deaths of innocents are involved.

These are the deaths that are never forgotten by communities. The stories are passed down through families, the bitterness lasting a generation.

As we should know from closer to home.

Bloody Sunday was one of many horrors in the Northern Irish Troubles when innocents were killed. But it’s the one we remember. Who could quantify its repercussions? It was a call to arms for the terrorists and a fund raiser for their cause. The cover-up that followed robbed an entire community of its faith in British justice. Now think of Afghanistan and Iraq and how many innocent deaths we have caused there as a consequence of war?

If we bomb, what will it be in Syria?

To be honest we are almost unaware of the impact we have on ordinary people in faraway countries when we go to war. We professionalise our wars; sanitise them, talk of smart weapons and our television always show direct hits on command centres or ammunition dumps.

We send troops to do our dirty work and watch the fall-out from our sitting rooms.

We have drone operatives stationed in Leicestershire flying missions in the Middle East. It must feel like playing a computer game but with real consequences. Unless we have family members in the forces, our lives continue along their peaceful, untrammelled course. Until, that is, these terrorists bring the carnage to our streets.

Then, like the population of Paris or before that Madrid or London on 7/7 we find ourselves shocked and persuaded of our own status as innocent bystanders. We react in anger and outrage. We rush to arms again – and the wheel spins.

I am not being naïve. I know that in IS we have a challenge to our precious way of life. It is under threat from their determination to pick soft targets. It’s also under insidious attack from the surveillance measures the state insists on to aid its fight against them. I’d go further and say it is under attack from our communal disregard for what is happening beyond the cocoon of our everyday existence.

I am reminded of Edgar Allan Poe’s story of The Masque of the Red Death. As I recall it, while plague invades the streets, Prince Prospero assembles 1,000 merry friends in a remote castle. There they live in safe splendour. Then the prince organises a masquerade and into the midst of the revellers comes an unknown. It is some time before they realize that moving amongst them is the Red Death itself.

It is amongst us now. We have to fight it to preserve our right to life, to freedom, justice and liberty. We must defeat it to ensure our security and sense of safety.

The question facing our political and military leaders is how?

I don’t have the answer. There are wiser, more experienced people to advise the decision-makers. But this I do know. If we are to fight for the principle of individual liberty we must be as assiduous in its defence in those unfortunate countries where Islamist fanatics are based as we are at home.

And we should recognise that war, even modern precision aerial bombing, always endangers that intention. I just wish that David Cameron would change his tone to acknowledge that the arguments for and against are finely balanced.