Aside from the usual April Fool’s Day tomfoolery, today has begun with debate over a letter from 100 prominent business people to the Times warning about the impact of a Labour government on the economy.

As one would expect, the responses to such a letter are tiresome and predictable.

The Tories crow over their economic record and the support they have “won” from people who would probably always have voted for them.

Labour point out that these people would always have supported the Tories and anyway they are all tax avoiders.

A few Lib Dems pipe up to suggest that if the past five years have gone well, maybe it’s something to do with Vince Cable being Business Secretary. They are ignored.

It’s all pretty unexciting and unedifying. But it does serve as a good illustration of the problem of lack of ambition. This is a big part of what is crippling our politics, and why voters often don’t care, or say all the parties are the same.

A voter (even one like me) looks at this letter and goes through this kind of thought process.

So the Tories are content to rely on the support of their core voters at this election? That’s fine if you’re a wealthy businessman, or looking to become one, but what about me? I’ve got nothing in common with people who work in glass towers. I’m not sure I want to vote for a party that so transparently values such people higher than the rest of us.

What about Labour? They don’t seem interested at all in addressing what these people are saying. Their argument amounts to “well, we could never have reached them anyway, so why bother?” I’m not sure I want to vote for a party that isn’t willing to appeal to voters that aren’t a natural fit.

Hmm. Anyone else about?

This isn’t to suggest that other parties don’t fall into this trap. I’m a member of the Lib Dems partly because I believe they want to represent and speak for the whole of society. The party has very few vested interests.

But the party has suffered in government from the same affliction that affects the larger parties. The campaign this time around is based on warnings about the other two and what they would do on their own. That’s fine as far as it goes – some might say it’s even a necessary part of modern politics – but it’s hardly ambitious or visionary. For the fictional voter above, it gives nothing to grab on to.

If parties genuinely want to avoid a further haemorrhage of political support to the fringes and backwaters of nationalism and xenophobia, they must address their own lack of ambition. It’s highly ironic that their desperation to hold on to power blinds them to this greater and more strategic need.