I respect Jeremy Corbyn's principled argument against extending bombing into Syria. I don't agree with him, but I understand his position, and respect the sincerity with which he argues it. I think his stance is misguided, as with many of the other idealist positions he takes on muddy real-world problems.
Yes, Iraq descended into chaos because there was inadequate planning for how to "win the peace" and rebuild after 2003. Intervention using force in another country is regrettable and carries a heavy weight of responsibility. Looking at Syria today, it is many times more difficult than it was for Iraq a decade ago to foresee how to rebuild after the war, or even who will hold most of the territory (and hence the cards in any political settlement), once the Daesh Caliphate has been erased.
But erased it still must be. I do not view inability to foresee what happens next as a justification for doing nothing now. Unlike Iraq then, what is going on in Syria has already torn the country apart and put it in the hands of a great evil; IS makes terror plans from Raqqa that extend beyond the territory it holds to within our own borders; and the more we can do to disrupt its plans, and progress towards retaking its territory, the better.
Of course it matters whether that is by Assad's Russian-backed government troops, Kurdish Peshmerga, US-armed Free Syria Army forces, or Iranian-backed forces. Nobody has forgotten that Assad used chemical weapons and barrel bombs to try to win his civil war. But every one of those myriad groups, even Assad's men, represents a better option than the IS Caliphate.
If politics is the art of the possible, then the same must be said of international relations. Foreign policy is often about choosing the lesser of many evils. It should always have a core of ideals and values, but its application is also hostage to pragmatism. I don't think Corbyn's idealism provides the necessary flexibility for that.
For example, I'm all for raising a debate on whether we should scale down our alliance and cooperation with Saudi Arabia's oppressive regime, perhaps going as far as sanctions and dropping lucrative defence deals that create jobs and wealth in the UK. To prop up their corrupt monarchy the Saudis have done much to encourage extremism.
But any debate on that issue would again be about pragmatism: do we gain enough from the relationship to tolerate them; and does it outweigh what it costs us in security and hypocrisy. It's an open question, but it isn't enough to answer it with principles alone. Costs and benefits are paramount, particularly when the calculation is about our national security.
And on national security, the other aspect why I disagree with Corbyn is his natural pacifist leaning. I suspect he would hesitate to employ military force even if the case were remarkably clear cut. He is instinctively against the role of defence, deterrence, and the threat and use of force, within a robust international policy, which accepts that Britain has a major role to play and responsibilities in the world beyond our own shores.
Corbyn would end any expeditionary capability in our defence, as well as removing or undermining our nuclear deterrent (the whole point of which is that it is never used). He would rather see our Armed Forces cut down to a narrow vision of defence, restricted to our own shores, while questioning any weapons that could be used more offensively. If the world were a safe place, I might agree with him. But it isn't. Threats abound from those who would harm us. Threats also change rapidly. I can't predict them; he can't; nobody can. It would be breathtakingly naive to disarm today, only to leave ourselves unprotected against new threats tomorrow.
The reality is that for the past two centuries, only two powers have policed the globe effectively: ensuring long periods of relative peace spanning many decades; encouraging the development of the globalised international system we know today; and making sure the right side emerged victorious when major conflicts have punctuated the peace. Those countries are the US and UK.
Self-interest has always been a strong motivation in that policing role, but our moral principles (though often flawed and deployed inconsistently) are also traceable throughout. Stepping back always creates a vacuum that others can fill. I believe in the values Britain stands for, and I would rather we play our role in the world, than outsource it to others, or, worse, allow evil to fill it.