Interestingly, so did the Tories.
Mostly we think that political debates are zero-sum. If something's good for Labour, it's bad for the Tories and vice versa. So why would both parties want to do the same thing? There are a few possible reasons:
- Both parties may think it boosts them at the expense of the Lib Dems. That's certainly possible - because it focuses attention on them and entrenches the idea that it's a straight choice between the two main parties.
- One party may be mistaken. Perhaps they both think it's in their interest to have this out, but one of them is wrong. That's possible too, though we will never know for sure.
- Most intriguingly, it may not be about the interests of the parties but of the campaigners. At the start of any campaign it is not clear what issues the public will care about, or what the parties should pick as their theme. This presents a real psychological challenge to the people working in those parties. Without certainty about their exact short-term goals, or whether they are doing what they should, the press people and campaigners will be psychologically lost. But as soon as a clear theme emerges, they have a message to concentrate on, a coherence to their actions and immediate feedback on whether their behaviour is successful. What's more, it's harder to blame someone after the event if they can say "we had a clear philosophy and the people chose the opposition" than if they never knew what their message was. Update: This is a good example of uncertainty aversion.
- Another update: Perhaps both parties want to move on, but neither is willing to let the other have the last word. Remember the centipede game where both players destroy themselves because they can't coordinate and agree the right point to stop?
Better, I think, for Labour to have a clear position and defend it strongly, than try to avoid the issue. The clearer the choice for the public, the less they will be led by the priming of their prior attitudes to Gordon Brown and the government.
Although this clarity should help Labour, it won't entirely overcome previous attitude. An important secondary debate, spun off from the NI discussion, is about public sector efficiency. Labour's argument here is that they have already identified all the realistic savings to be made, while the Tories say there are still more. Almost nobody is in a position to make an objective judgment on this, so instead voters will suffer confirmation bias, meaning that their existing assumptions about Labour or the Tories will be confirmed - if they believe in Brown already, they will believe him on this issue, and vice versa.
This is one key reason why more business people are supporting the Conservatives - because it confirms their existing belief, based on their own business experience, that the public sector can be made much more efficient. One cautionary note on that, from a comment I made elsewhere:
Private companies primarily achieve their efficiency not through cleverer ways to organise their production, or investment in smart technology. They do it by selecting their best markets. A business can focus its attention on the 80% of easy customers and drop the 20% that are troublesome, or which do not suit its business model. Pret a Manger does not try to make food for everyone, just for those who like sandwiches. Private health providers do not focus on expensive mental health work or AIDS treatment, they prefer to work on profitable knee replacements and chiropody.
The public sector cannot do this, because it would be politically unacceptable. So it must continue to service the whole of the population, including that last 5% which represent 50% of the cost. This is a major difficulty in finding public-sector efficiencies, and requires hard political choices, not just better management. [more on this here]