Should we bomb ISIS?
The question is not "should ISIS be bombed?" but "should the UK join in fighting alongside the US and France?" There are several lines of argument to say that the UK should, none of which convince me but a couple of which I am not in a position to reject, either.
The Basic Consequentialist Argument: Bombing ISIS will help bring peace to the Middle East.
Sure, but France and the US will do that. The marginal effect of the UK intervention is probably close to zero. (This also hangs on the assumption that bombing will make things better, but I'm happy to outsource my empirical beliefs regarding Middle Eastern geopolitics to the generally pro-intervention Anonymous Mugwump).
The Fungibility Consequentialist Argument: (1) UK bombing will reduce the amount of bombing by other powers. (2) The collateral damage of UK bombing will be less than the collateral damage that would have been caused by the bombing which is funged away.
(1) is probably true to some extent, at least with regard to France and the US. I doubt Russia will bomb less just because the UK intervenes, since (as I understand it) they are after all bombing a different faction. (2) is less convincing - I know of no particular reason why we would expect UK strikes to be better target than those of France or the US. That said, it's certainly possible. Mark this argument down as a "maybe".
The Kantian Argument: If no-one bombed ISIS, then bad things would happen. So, in accordance with the categorical imperative, we should bomb ISIS.
Firstly, Kantianism can't necessarily be applied to states in the way it can (supposedly) be applied to individual people.
Second, the application of universalisability is always finicky. Clearly one can (for example) work as a carpenter, even though if everyone were a carpenter then we would starve. So where there's something that needs doing by someone, a better rule might be "do this thing if it is your comparative advantage". In which case, it really isn't obvious that the UK has that advantage.
Third, for Kant's maxim to apply it is not enough for bad consequences to apply - this state of affairs has to be self-contradictory. Murder is forbidden, according to Kant, because you can't kill people if you have yourself been killed first. Theft is forbidden because if everyone were a thief, the concept of property would cease to have meaning. Homosexuality is forbidden because it's disgusting. If no-one bombed ISIS then they would grow, which would be bad, but not self-contradictory. Honestly, what do they teach in the Oxford Philosophy Curriculum these days?
The We Can't Just Let This Happen "Argument". File under "Copenhagen Fallacy".
The Membership of NATO Implies Obligations Argument.
As a philosophical anarchist I'm sceptical that the UK public could have an obligation to pay for a war based upon a treaty signed by their government. Leaving that aside, if France were genuinely threatened then I would (with about 90% confidence) advocate intervening to defend them. But they're not! This isn't the Third Reich in full Blitzkrieg mode, this is an unusually violent tinpot little Middle Eastern theocracy. France is perfectly capable of defending itself without the UK getting involved, just as it is capable of managing its own police force without us sending over a corps of bobbies.
The National Self-Interest Argument: The UK needs to be actively involved in international affairs, or else will be subject to whatever other nations decide to do to us. In this case, that means bombing ISIS.
This is, for me, the most compelling argument. It's easy to overstate the costs of isolation - in fact, the form of this argument that I endorse is fairly similar to the last one. If the UK had no mutual defence treaties with France, I would definitely not advocate intervention. Given that we do, it's probably better that we avoid being seen as betraying our friends. (What would the consequences of being seen this way be? It's hard to know. Earl Bute's treatment of Frederick of Prussia in ending the Seven Years' War and Britain's resulting diplomatic isolation was a significant contributing factor to the loss of the American colonies. This being the twenty-first century, we wouldn't get invaded by anyone if we were isolated, but we might get fewer trade deals, for example).
I would have advocated a minor intervention for the sake of show. More than that seems pointless, but (given that the marginal effect will after all be very small) no more impermissible than most things that governments do.@roreiy @Sam_Dumitriu That argument aside, my preferred policy is "roll up, drop half a dozen bombs, then bugger off for tea and medals."— Andrew Pearson (@adrwtp) December 2, 2015
That was not, of course, an option. The only people with votes were MPs, and they only had the options of voting for or against. Were I an MP with a free vote, I'd probably have decided that France and the US will get over it, especially if David Cameron wanted to join them but couldn't get parliamentary support. They seem to have got over the last time this happened, back in the dark mists of 2013.
Were I a Tory MP, I guess I'd have gone along with the three-line whip to vote in favour. Rebelling all the time might keep your hands clean, but that's about all it does. Freak accidents aside, a consistent rebel will never be able to lead the party in their preferred direction - and when those freak accidents do occur, you can hardly expect your "colleagues" to be any more loyal to you than you were to them. That doesn't mean you never rebel, but it means you pick your battles with care.