The second world war lasted six years. The war on terror is now in its 15th year. And yet things are demonstrably no better. Why? Because we still have no vision of what peace might look like. For instead of trying to figure out what the politics of a relatively settled Middle East might be, and then working towards that, we think first about dropping bombs from the sky – bombs that will inevitably destroy both Islamic State and its non-Isis neighbours, bombs that will inevitably recruit new forces of vengeance against the west. Carl von Clausewitz famously said that war is politics by another means. And that puts its finger on the problem: we don’t have the politics sorted out. We don’t really know what we want to achieve other than to hear the sound of bombs falling on Raqqa, thus satisfying the need to do something. We can’t win if we don’t know what winning looks like.

War in time for Christmas is David Cameron’s plan. Yes, exquisitely timed to coincide with the Christian message of peace and goodwill to all. Yes, a perfect accompaniment to all those half-forgotten carols: “And man, at war with man, hears not, / The love-song which they bring: O hush the noise, ye men of strife, / And hear the angels sing.” Translated into the prosaically secular: we have no vision of peace.

Remember the 2003 invasion of Iraq. It took only a few weeks for US soldiers to reach Baghdad. Remember how they celebrated, tearing down statues of Saddam Hussein and forcing people who ran the country from office. That was the easy bit. The war began on 19 March and by 1 May the famous “mission accomplished” banner was unfurled on the USS Abraham Lincoln. Yet more American lives would be lost in Iraq after that speech than were lost before it. Mission accomplished? That’s the myth that needs busting. Even today, what remains of Iraq is a basketcase of blood and war and a school of festering hatred. A similar story could be told about Libya. In other words, retaliation is not a strategy for peace. And without a strategy for peace, we will continue forever on this deathly merry-go-round.

If we really thought destroying Isis would be the end of it, we would be sending in ground troops, rather than just poking them with a stick from the air. But we don’t have the stomach for ground troops because we don’t actually believe it would be worth the risk – we have lost confidence that it will achieve anything. Instead, Cameron is being suckered into the same military oneupmanship that did for Blair: show and swagger. It’s all about not losing face in front of the Americans. It’s all about being seen to be doing something. And the stuff that makes for peace is just too dull for the cameras, too soft-looking.

The first rule has to be that we must stop making things worse. Let’s not call this a war and dignify Isis with the honorific status of being an enemy army. Still worse, let’s not imagine we can win some preposterously imagined third world war against a particular strain of Islamism. You can’t destroy a violent theology with greater violence – you just up the stakes and feed the beast.

We wouldn’t bomb the suburbs of Brussels to eliminate the Isis cells stationed there. So why bomb Syrian towns when there are so many innocent people living there too? A few years ago, Cameron tried to persuade us to go to war against Bashar al-Assad because he was dropping barrel bombs on his own people. Now it is us who are proposing to do something similar, perhaps to the very same cities. Yes, our bombs may be more smart and discriminating. But not that much so. And many innocent people will die – mostly the ones too weak, too old or too young to run away. And as all these bombs rain down, a continuous trail of bedraggled humanity is filing out of Syria to find refuge in Europe. Cameron’s plan is to bomb their country by Christmas and then to bar those fleeing death from entering Europe to find safety. No room at the inn, he says.

@giles_fraser