Expecting coherence and consistency from Sinn Féin in matters of economic policy has long been the Irish political equivalent of the pursuit of the Holy Grail to early Christians.
After all, this is the party that voted for the bank guarantee with Fianna Fáil, who wanted to tell the troika to take a hike with their money in 2011 when nobody else would give us any, and who believe that Syriza and Greece represent the kind of economic model that the people of Ireland should aspire to.
Well, the people of the Republic, at least. Because, as we all know, Sinn Féin in Northern Ireland pursue totally different policies which have led to widespread public sector strikes and welfare cuts not seen in the south since Fianna Fáil were in office.
Matters, however, have taken a new turn in recent days. Sinn Féin, which has opposed everything the current Government has done to rescue our economy, is taking its blanket opposition to all policies a stage further. In a weekend article, the party's foremost intellectual, Eoin Ó Broin, has indicated his party's opposition to tax reductions for all - including low and middle-income workers. The Government's "promise of year-on-year income tax cuts is a recipe for disaster," he said.
Perhaps we shouldn't be too surprised about this. After all, Sinn Féin, led by Gerry Adams, Mary Lou McDonald and finance spokesperson Pearse Doherty voted against the tax reductions delivered in last year's Budget by this Government.
Indeed, to justify their position, they tell consistent lies about to whom those reductions were directed, by neglecting to mention the increase in the Universal Service Charge (USC) rate for those earning more than €70,000.
But to see them opposed to tax reductions as a matter of principle as enunciated by Eoin Ó Broin is a new development.
Apparently those who pay 7pc USC on earnings over €17,500 are no longer deserving of a tax reduction.
Apparently those who face a marginal tax rate of 51pc on earnings in the region of €34,000 are no longer deserving of a tax reduction. So workers who thought Sinn Féin might have been on their side can think again. They are not. This volte face, if that is what it is, is justified on the basis of prudential management of the economy. Now, Sinn Féin are a bit late to this argument as the Irish people know well. If the Irish people want to know what Sinn Féin in Government looks like, there is a full live experiment under way in Greece and it doesn't look pretty.
Thankfully, the Irish people have been spared the crisis that now faces the unfortunate Greeks, but that is no thanks to Sinn Féin.
Mr Ó Broin's new departure appears to be based on his reading of the Government's Spring Statement. Now, there are none so dangerous as those who know a little, and clearly Mr Ó Broin knows a little. He seems to think that the statement doesn't contain enough public spending out until 2020. Strange that, given the statement is based on no-policy change between 2017 and 2020 - in other words, the size of public expenditure increases is broadly to be determined closer to the time.
Were that not the case, Mr Ó Broin would be decrying the Government for prejudging the outcome of the general election. You can't win with these guys.
The statement, too, is explicit that the Capital Review to be published in June will also contain additional public investment.
Of course, there is a fundamental difference between Sinn Féin and Labour on these issues. We want to see people back at work. It is better for the individual and it allows public resources to be directed towards frontline services.
Sinn Féin clearly see additional public spending as an end in itself - within five minutes of their response to the Spring Statement, they had expended billions of notional taxpayer euros on various projects. Mr Ó Broin can rest easy. This Government is determined to ensure there is enough money available for investment in quality public services. We are determined that the tax burden on working people is reduced to incentivise work. We are determined to get our debt burden down in a slow and deliberate fashion.
The Spring Statement is not a prescriptive document; it is a framework in which any political party can set out their priorities within the overarching parameters.
Within a week, it appears to have caught out Sinn Féin. What Sinn Féin are about was always unclear. They have spent five years trying to be all things to everybody. But after Mr Ó Broin's latest foray some clarity is emerging on their attitude to those on low incomes, but high tax rates.
Sinn Féin may have the beginnings of an economic policy. It is incoherent and contradictory but what most voters will want to know is that USC and income tax reform are no longer part of it.
Alan Kelly is Minister for the Environment and deputy leader of the Labour Party.