Last night the UK’s House of Commons voted to extend the bombing of IS from Iraq into Syria. The military effect may be slight, but perhaps not entirely insignificant. The vote is nevertheless of huge symbolic importance.

What can justify intervention by one country in the affairs of another?

Two arguments can be made: the first, that the rightful interests of one country or its allies must be protected, the second, that absolute wrong should be prevented.

The first argument has clear historical precedent, and is usually based on the vital interest of self-defence. Mere economic interest or the protection of property has faded as justification.

The second argument has become more fashionable in recent years, as global consensus has emerged around human rights, and as the arguments of moral relativists that ‘good’ depends on culture and perspective have weakened.

The second argument is particularly complex and lays governments open to accusations of inconsistency, cynicism and hypocrisy. Whatever level of suffering and oppression is considered as justification for intervention, that level must be consistently applied – why act to prevent the oppression of women or of gays, or of one race by another, or to prevent ethnic cleansing in one country, but not in another?

Before any justification can be advanced the objectives of intervention must be well-defined. And justification must take account of means – should hard military power be used, or the more softly persuasive power of diplomacy, economic dependency or foreign aid?

Whichever tools are chosen the economic and moral cost of intervention must also be acceptable. There comes a point when ‘collateral damage’ or, for example, the impoverishment of a population, might outweigh any good that’s achieved.

Objectives must also be practically achievable, both in the short-term and the long-term. The short-term usually carries more weight since the short-term is generally more predictable. As time passes, possibilities and unintended consequences multiply. Sadly, these also include the unintended consequences of success.

So, in the case of the bombing of IS in Syria:

• Are the objectives well defined?
• Is there self-interest at stake?
• Are there absolute wrongs to be prevented and have such wrongs been addressed consistently?
• What are the best means of achieving the objectives, in the short-term and the long-term?

Objectives

I am not sure what they are.

Tactical intervention, with the assistance of ground troops, such as the Kurdish Peshmerga, has limited and rolled back some of IS’s conquests.

Destroying IS’s control of oil fields and distribution has limited its capacity to raise money for arms.

Destroying IS’s command and control centres has limited central command and control.

But if justification is based either on self-interest or the prevention of wrong, then the objectives must go beyond these tactical ones. They must be strategic, and must include the eradication of IS’s radical Muslim ideology.

But if this is the objective, what does it mean in practical terms?

• Does it mean military occupation of the entire area currently dominated by IS? And for how long?
• Does it mean establishing long-term institutions (political or religious) that are immune to such ideology?
• Does it mean establishing economic prosperity to reduce vulnerability to this ideology?

Some, or all of these practical steps, and more, are surely essential.

Justification

I don’t hold with the argument based on domestic self-defence. The UK  may already be an IS target, and it will be more so now. We must expect atrocities in our streets.

I do, however, accept that an argument can be advanced on the basis of preventing wrongs, wrongs such as the oppression of women, of gays, denial of political freedom or freedom of expression, economic subjugation, legal inequalities and so on. The most moving aspects of Hilary Benn’s impassioned speech last night focused on the killing of gays, Yazidi women and the professor of archaeology at Palmyra.

But is this sufficient justification? The protection of rebels in Benghazi was the immediate justification for intervention in Libya, but Libya is no better place now because of it.

If this argument is a sufficient justification we must apply it consistently. Saudi Arabia is about to execute dozens of political dissidents. It beheads its citizens on a daily basis. Gays and women are oppressed. Likewise in many African states. Human rights in China? In Korea? Our interventions would never end.

Self-defence (protection from Weapons of Mass Destruction) was the core justification for intervention in Iraq, with prevention of cruelty a close second. The first argument was based on wilful self-deception (at best), and, as with Libya, it is hard to see that intervention has lessened local suffering.

Means

Tactical military intervention will assist with push-back, but you can’t bomb an idea. If anything, bombing will exacerbate the problem. There are thousands of resentful villagers and families eager to avenge the killing of each IS warrior or of civilians who got in the way.

Military defeat of IS won’t be achieved without boots on the ground. I don’t believe that there are 70,000 local troops who share the West’s objectives and who are willing to complete the job of military occupation.

Robert Fisk has written extensively about the delusional view that Iraqis would welcome invading forces with open arms, many of them villagers who had endured years of ‘Western’ bombing, including bombs and shells made of depleted uranium.

Long-term good won’t come from bombing. If there must be bombs then even more strenuous efforts must also be made to rid Syria and Iraq of toxic radical Muslim ideology. I don’t see that achieving peace in Syria (a well-nigh impossible task in any case) moves us much more than a millimetre forward in achieving that long-term objective.

So, in the case of the bombing of IS in Syria:

• Are the objectives well defined? NO
• Is there self-interest at stake? NO
• Are there absolute wrongs to be prevented and have such wrongs been addressed consistently? YES and NO
• What are the best means of achieving the objectives, in the short-term and the long-term? NOT BOMBING, BUT I HAVEN’T ANY BETTER IDEAS