So of all the questions that we should be asking Labour under Ed Miliband – all the many blank patches in the policy canvas that need filling in – the single most revealing is both incredibly simple and incredibly old-fashioned: how much do you intend to spend?
Now, you could argue that we've got so many years of austerity ahead that this point is simply moot. Indeed, when someone at an Institute of Economic Affairs/TaxPayers' Alliance briefing on the Autumn Statement pointed out that the IEA's long-term objective is to bring public spending down to 30 per cent of GDP, from its recent height of 51 per cent plus, there was hollow laughter.
Yet actually, it's a question that goes to the heart of our national future – and of Labour's fitness to govern. Because state spending of 42-43 per cent of GDP isn't some natural, historic average. It goes up and down as the governments of the day dictate – and when it goes up, prosperity goes down.