When Douglas Carswell left the Conservative Party for UKIP he had a variety of people in mind. He felt the Prime Minister and his coterie were duplicitous and deserved a bop on the nose; he felt his own principles were poorly served by his former party; he felt Farage and co. offered him a better opportunity to advance them.

The people he didn’t appear to particularly have in mind were the allies he left behind. What impact might his decision have had on them?

There are two main schools of thought about the effect of the defection on the many eurosceptics and Better Off Outers who remain in the Conservative Party. Westminster watchers disagree all the time about quite what events mean, of course – we’d be redundant if we didn’t – but it’s rare for one event to draw such completely opposed commentary.

Theory 1: The eurosceptics have become more powerful. Carswell dropped the first nuclear bomb and in so doing gave other MPs of similar views a deterrent threat to use on the Prime Minister. Here’s what one told Isabel Hardman:

‘As a result of Carswell’s defection, Eurosceptics now have an exit threat. One of them explains: ‘What this means is that when ten of us go in to see the Prime Minister to ask him to give more details on his renegotiation package, he knows that if he doesn’t give us what we want, more of us will defect.’’

Theory 2: The defection has severely harmed the remaining eurosceptics. Carswell has demonstrated us to be an untrustworthy source of danger to our party, ready to defect at any moment. Not only are we insatiable in our demands, it is claimed, we are unreliable and will only repay concessions with betrayal.

Neither option is particularly attractive.

Theory 2 is unfair and inaccurate. The majority of our party is increasingly eurosceptic, and it is wrong to try to smear hardworking, loyal activists, candidates and MPs in this way. Instead of trying to drive out such people, we should be working at attracting more of them.

Some of its advocates will seize any opportunity to score ideological points – they would rather nothing ever happened to remove the EU’s power, and this is a chance to further that aim. Others are unable to shake off their shell-shock from the 1990s and thus assume any euroscepticism is a road to defeat, having failed to notice the world has changed.

But Theory 1, which at least one anti-EU MP is apparently espousing, also does a disservice to Conservative eurosceptics. This “exit threat” will only work to put pressure on the Prime Minister if it is credible – in essence, it relies on whipping up exactly the same doubts about eurosceptics’ loyalty as Theory 2.

We eurosceptics are right to object when pro-EU commentators claim the Conservative Party would be Better Off Without us – as Paul wrote earlier in the week, the party belongs to us all, not to one clique. But to object to an allegation of unreliability and then threaten that you might indeed defect is obviously dangerous, even if it’s a hollow threat. When you find yourself constructing a self-image which matches the cariatures which europhiles paint of you, it’s worth checking that you aren’t doing their job for them.

Those of us who are concerned about the impact of the EU on our country – the erosion of democracy; the harm done by over-regulation and protectionism; the pursuit of economic stagnation in the old world rather than embracing opportunities to trade with the new – have a great responsibility. Our job isn’t to be angry, to spite our opponents or to raise merry hell for the sake of it – it’s to secure the democratic self-government of the UK, and to pursue a better future.

What we do in our cause today ought always to advance it tomorrow, never to harm it. Threatening to defect may very briefly increase an MP’s clout with Downing Street – though I doubt it, as no-one reacts well to being menaced. Even if it did give them a boost for a short moment, in every other way it undermines euroscepticism and weakens its chances of success.

One defection has given our opponents a chance to falsely accuse us all of disloyalty – a threat of another will help to bolster their attack. That wouldn’t bring our independence any closer.