It's often forgotten that Ed Balls isn't the only economist on the Labour frontbench; Ed Miliband also taught the subject at Harvard while on sabbatical from the Treasury and he gave David Cameron a suitably stern lesson at today's PMQs. In a stat-heavy assault on the coalition's economic record, he reminded Cameron that the economy had grown by just 0.4 per cent since October 2010 (it was expected to grow by more than five per cent), that the UK had grown more slowly than 17 of the G20 countries and that this was now the weakest recovery for more than a hundred years.
Confronted by that record, Cameron played a bad hand as well as he could. He was aided by Labour MPs who foolishly cheered when he conceded that the economy shrank by 0.3 per cent in the most recent quarter, an error that the PM quickly pounced on. "Only honourable members opposite could cheer that news," he fumed. From there, he ridiculed what he called Labour's "three-point plan": "more spending, more borrowing more debt".
After Miliband noted that the deficit so far this year was £7.2bn (7.3 per cent) higher than last year, Cameron replied, "if he thinks there's a problem with borrowing, why does he want to borrow more?" It is the question that Labour has struggled to answer since the election. The Tories' credit card analogy may be a hackneyed one but it is easier to explain to the electorate than Keynes's paradox of thrift. In response to Cameron, Miliband cried: "he's borrowing for failure!" The Labour leader's hope is that the public will distinguish between the coalition's 'bad' borrowing, driven by higher welfare bills, and his party's 'good' borrowing (a VAT cut, national insurance holiday, higher infrastructure spending and the like ). But without explicitly declaring that Labour would borrow for growth (and explaining why), he risks reinforcing the impression that borrowing is always and everywhere a bad thing.
Miliband, aware that polls show  more voters continue to blame Labour (26 per cent) for the cuts than the coalition (21 per cent), has never conceded that his party would, at least temporarily, borrow more than the coalition. For now, with the public more worried about the disappearance of growth, he can avoid further scrutiny. But at some point before the election, Labour will need to say what its plans would mean for deficit reduction. Anything else will allow the Tories to claim they'd make "the same mistakes" all over again.