Their reluctance to get involved in the normal political mud-slinging with a rival party was puzzling because even a casual perusal of the Sinn Fein document highlights an economic philosophy that seriously risks returning Ireland to the bad old days of the 1980s.

The party's focus on "putting low-income families first" is admirable, but its means of trying to achieve that are hugely open to question and, if implemented, would hurt the disadvantaged in society the most.

Sinn Fein is proposing a series of socialwelfare improvements and tax cuts aimed at lower earners that would cost in excess of 3.7bn. This would represent a staggering and totally unsustainable level of increase in annual expenditure. Even during 2000 and 2001, when the government totally lost the run of spending, the tax and social-welfare packages in the budget were only half that level.

Two weeks ago, Brian Cowen announced that total government spending . . . that's everything from wages, to infrastructure to the health service . . . would increase by 4bn next year. Sinn Fein is proposing to virtually match that figure in tax cuts and social-welfare increases alone. It is important to remember that this would not be a one-off payment . . . as with a major infrastructure project . . . but a cost that would have to be borne year in, year out. The immediate impact would be to bring an end to the decadelong period of budget surpluses, putting the exchequer back into the red. The potential impact on the public finances if there is a downturn in the economy doesn't even bear thinking about. It would be like 1977 all over again.

But perhaps even more worrying than the expenditure increases are Sinn Fein's proposals for revenue generation. The suggestions come nowhere near explaining how the tax and social-welfare package can be afforded but, if they were ever implemented, they have the potential to do serious damage to employment prospects.

First and foremost in that regard is the proposal to increase corporation tax from 12.5% to 17.5%. The huge level of foreign direct investment in Ireland has been one of the major factors in the Irish economic success story. Suggesting tampering with that successful formula beggars belief.

We can talk about an educated Englishspeaking workforce, the persuasive skills of the IDA, EU membership, etc, etc, until we are blue in the face. But the major reason why huge US multinationals chose to establish operations here is because of our low corporation-tax rate and the certainty that it will remain low. With a number of countries now looking to match, or even go lower, than Ireland's rate of corporation tax, there would be no shortage of alternative centres for their investment if those corporations thought that would change.

But it's not just foreign investment that would be put at risk by increasing the corporation-tax rate. Investment by Irish people in the economy would also be affected, potentially undermining the progress made over the last decade in making Ireland a more genuinely entrepreneurial country.

Sinn Fein's proposal to double the capital-gains tax rate from 20% to 40% . . .

reversing one of Charlie McCreevy's earliest budgetary measures . . . is not a new one.

It is favoured by those on the left who see the 20% rate as the state effectively subsidising the wealthy. But the facts, as opposed to ideology, show that McCreevy's decision to halve the rate was the correct one. In the first year after he cut the capital-gains rate, the take to the exchequer doubled and revenue from this tax has been enormous ever since.

Sure, you can send out a strong signal of your proletariat credentials by hiking the capital-gains rate, but it is virtually guaranteed that the revenue generated . . . the main point of taxation after all . . . will fall. In a globalised world, capital is extremely flexible. It can and will quickly migrate to more attractive climes.

The third tax hike envisaged by Sinn Fein is a 50% tax rate on those with incomes over 100,000. The problem is that the genuine high rollers don't pay tax at the current top rate of 42% rate to begin with. And stiffing high-earning PAYE workers with a 50% tax rate will simply encourage many of them to check out employment opportunities in Britain and elsewhere. We tried high rates of personal tax in the 1980s and the result was massive unemployment, high emigration, low tax revenue, huge budget deficits and much higher levels of poverty than exist today. Low tax rates have consistently delivered enormous levels of tax revenue that have funded generous increases in social welfare and we should be extremely wary of anyone or any party that seeks to change that winning formula.

It may only a matter of time until Sinn Fein is part of a government south of the border. That is to be welcomed . . . but definitely not with this set of economic policies.