Election 2015: David Cameron just made a very silly promise and it's our fault

General elections are not the best time to follow politics but the worst. Apart from the day of the vote itself, they are rarely exciting and much of the campaign is taken up with pledges that will never come to fruition and endless polling masquerading as thoughtful analysis. David Cameron's pledge to enshrine in law a promise not to raise income tax, VAT or National Insurance in the next parliament fits the first of these to a tee.

The so-called "five-year lock", announced by Cameron to great fanfare on 29 April, is the perfect election giveaway in its utter stupidity. Under the proposed policy, even if another financial crisis were to rock Britain and there was an urgent need to raise government revenue, Cameron is locked in for the next five years: taxes can't go up without a change in the law, which takes time and could prove tricky.

We ought to have learned from the 2008 crash that economic crises require a nimble-footed political response. In seeking to win the general election for the Conservatives, David Cameron has made a rod for Britain's back in the event of another crash. He has also reversed Keynes's common sense injunction that "when the facts change, I change my mind". It might just as well now read: "Even if the facts change, I can't change my mind."

This is perhaps why the head of Standard Bank, not someone traditionally associated with left-wing economics, is warning that Cameron's tax pledge "could cause monumental damage if it has to be defied in the event of a deterioration of the economy".

Enshrining in law something a government may very well wish to revoke at a later date is a sign of weakness rather than strength. Weak people often do silly things in an attempt to over-compensate. As well as tacitly accepting the premise that the rest of his party's general election pledges are worthless, Cameron appears to recognise he is not trusted by the electorate on the issue of taxation.

This probably has something to do with the fact that the Conservatives promised not to raise VAT prior to the last election - only to jack it up once safely ensconced in their ministerial cars. Put another way, we are risking the future prosperity of the British economy with an ill-thought out "law" because Cameron is a bulls**tter.

More depressing perhaps is the conceited assumption on the part of the Conservatives that voters always and every way want deeper cuts to public services over higher taxes. The shrieking right-wing newspapers would certainly like you to believe that this is where the British public sits, but the facts suggest otherwise.

According to ComRes polling from 2014, almost half of the electorate would be willing to pay more income tax if the money went to the NHS. According to polling by YouGov, 42% of the public favour giving public services more money and investment even if it does mean higher taxes. This contrasts with just 14% who wish to prioritise reducing taxation even if it results in public services having less money.

Not that the Tories have noticed. Instead they've pencilled in massive spending cuts for the next parliament – cuts which will make those since 2010 seem like a pin prick. And if the Conservatives do win another term in office, those swingeing cuts are locked in. They are happening because the Conservatives have left themselves zero wiggle room, either over their deficit reduction programme or over taxation. Deficit reduction in a future Tory parliament will come almost exclusively at the cost of cuts to departmental budgets and public services.

Giveaway addiction

Yet despite the frivolity of Cameron's announcement, perhaps it is ultimately us, the electorate, who are to blame. So attached have we become to pre-election "giveaways", and so demanding are we to be "inspired" by the policy offerings of politicians, we appear to have forgotten that government by definition requires an element of compromise and flexibility. We demand the big irreversible game-changing policy when the game may very well have changed considerably in a few short years.

'Many people see the DUP as the Northern Irish equivalent of the BNP. Cameron should declare that there will be no post-election deal until the DUP embraces respect and equality for all the people of Northern Ireland.'

Read Peter Tatchell's plea with David Cameron to cut ties with the DUP here.

In an age when coalition government is increasingly the norm, it's more important than ever to allow politicians to change their minds. A coalition of rival and obstinate ideologues is a coalition that gets nothing done. Liberal Democrat leader Nick Clegg is routinely savaged for "selling out" over tuition fees, yet he was also a victim in a sense – the victim of an over-hyped and unrealistic pre-election "offering" to win over students. An offering that no one – not least the Liberal Democrats – expected to come to fruition because no one expected the Lib Dems to be anywhere near power.

Politicians shouldn't make pledges they will struggle to keep. But if we don't want a diet of empty - and in Cameron's case, dangerous - promises, we might also have to reign in our own otherworldly expectations. Taxes might have to go up in the next five years. Lots of things might have to happen. We can't know because we're not there yet, and we don't know in what shape the economy will be in. And that's fine.

Or at least it's better than the alternative – shambolic "laws" that attempt to control the future.

James Bloodworth is editor of Left Foot Forward, one of the UK's top political blogs. You can follow James @J_Bloodworth and his blog @LeftFootFwd.