General Election 2015: Tory promise not to raise taxes was a foolish move

Considering the prospect of a hung parliament, the Conservative pledge not to raise taxes is doubly foolish

If people don’t think a brand of washing powder will get their clothes white, stamping the word “guaranteed” over the slogan “washes whiter” is unlikely to persuade them. Thus, David Cameron’s promise of a law against tax rises is not just evidence of Conservative desperation but of his failure to understand psychology. If the voters fear a Conservative government would put their taxes up, promising to pass a law is hardly going to reassure them.

The promise makes no sense on its own terms. It is often said that no parliament can bind its successors. In fact, no parliament can bind itself either. If a majority of MPs pass a law, the same majority can repeal it the moment they realise that it was a bad idea. We can save the Conservative Party time by pointing out that it is a bad idea now.

It is bad for two reasons. One is that it constrains decision-making in the future in ways that may be contrary to the national interest. There has already been too much of this, from both main parties. Mr Cameron was pleased with his knock-out surprise in the last session of Prime Minister’s Questions, answering what Ed Miliband thought was a rhetorical question – would he rule out raising VAT? – with a simple “yes”. It won the moment, but it makes it harder to respond to future economic problems.

Labour has made a similar mistake, by promising to cut the deficit every year. That would not be sensible if there were to be another recession – an unpleasant and perhaps unlikely possibility, but one for which any responsible government should be prepared, as this week’s poor GDP figures reminded us. Ed Balls, if he were chancellor, would obviously rather break the promise than make the recession worse by cutting public spending at the wrong time.

However, the other reason yesterday’s Conservative promise is a bad idea is that passing a law is no substitute for political will. Using legislation as a symbol of seriousness is an abuse of process and likely to be self-defeating. Simply trying to increase the cost of breaking election pledges, by making it more embarrassing to do so, is likely to end in tears.

Indeed, Labour made exactly the same mistake as Mr Cameron is now making, by legislating before the last election to cut the deficit every year. The law was later simply repealed by the Coalition, sparing blushes (if not, presumably, a rougher sentence) because the deficit went up slightly in one year in the middle of this parliament.

The promise of symbolic legislation makes even less sense when everyone expects a hung parliament. It is part of the rhetorical cranking up of pre-election pledges – “red lines” and all the rest – in an attempt to increase their value in post-election negotiations. On that basis, parties will soon “operationalise” their manifestos, to use Michael Gove’s inventive language yesterday, by turning the whole document into draft laws to be haggled over in coalition negotiations.

In his desperation to shift opinion in an election that seems just on the edge of his reach, Mr Cameron is putting one of his strongest claims to re-election at risk. The Conservatives want to get the government’s books into surplus to put money aside for a rainy day, as the Prime Minister put it yesterday. But a law against tax rises suggests that a Conservative government would shy away from taking the tough decisions needed if the global economy should turn against it. That was an unnecessary act of self-harm.