There is only one certainty at present and that is that there is no certainty where predicting the economy's future is concerned. Short-term forecasting in economics is a mug's game at the best of times, always involving an element of luck.

In the current environment, forecasting economic performance is more difficult than ever. It means predictions are even more polarised than usual. When the economy was growing strongly it was easy to assume this would continue and few predictions were far out.

The current scenario is very different. The most bullish forecasters believe the global downturn will have only a slight impact on the Republic, while the most pessimistic believe it will affect the State even more than the US.

At first glance, the argument that it is impossible for such a small, open economy to recover quickly when those we trade with are in a downturn makes sense. Thus, the Republic cannot really recover economically until the US experiences a similar recovery.

Friends First's investment director, Mr Jim Power, is quite pessimistic.

He argues the high-tech and consumer bubbles in the US have burst and any recovery is likely to be gradual and will not begin before the second half of next year at best.

In addition, he argues that when emerging from recession US firms are likely to undergo a period of retrenchment rather than expansion and foreign direct investment could take some years to pick up.

This also assumes that no further terrorist attacks take place and the conflict in Afghanistan ends quickly. If not, things could worsen.

The ESRI's recent and more optimistic assessment of the Irish economy is also based on the assumption that there will be no further attacks on the US. ESRI researcher Mr David Duffy says its forecasts assume the US authorities will successfully prevent attacks.

"If not, we would have to look at the forecast again," he admits.

But even now there are still considerable fears. The markets almost panicked reaction to the plane crash in New York this week only serves to underline how jittery many investors are and how quickly they would react to any unexpected events.

However, NCB's Mr Dermot O'Brien believes that the impact of the multinational sector in the Republic has been greatly overstated. Mr O'Brien argues that the main impact of the downturn is on industrial production and trade figures. These areas are, of course, dominated by multinational firms. But he says the main impact is actually felt elsewhere - in the US.

"Ireland will not be that badly affected. Many people are confusing a slowdown in business growth with an economic recession. The slowdown in labour force growth is still the main determinant of how fast we will grow. The problem is that people do not know if what we have experienced so far is it or if it is merely a step on the way."

He even argues that the fact that the Republic is a very small, very open economy does not make it more vulnerable.

"The actual contribution to employment and to gross national product of the multinational sector is overstated."

Mr O'Brien points out that history suggests there needs to be a domestic impetus behind a recession - the impact on the tourism sector of foot-and-mouth is simply not enough.

According to his analysis, in the 1970s the economy was growing strongly on the back of strong growth in domestic demand, even though there was a negative net influence from the trade sector.

In the 1980s the position was broadly reversed. The external sector was buoyant as multinationals began moving in but the economy was depressed, with an overall loss in employment and mass emigration.

He also points out that the economic downturn in the 1980s was accompanied by high interest rates and high marginal rates of taxation, neither of which prevail today.

He contends that people are over-extrapolating, while some sectors will not be as negative next year and the State's exposure to multinationals is not as large as perceived. Others disagree.

One should also bear in mind that every recession is unique. This is the first time in recent decades that every area of the globe has been in or close to recession simultaneously. That must mean that globalisation now has a force that was simply not possible in the 1970s or the 1980s.