The Taoiseach has defended the ESRI's mid-term review, which was critical of some aspects of Government policy and appeared to distance himself from the Minister for Environment Mr Martin Cullen's claim that it was "nonsense".
Speaking at the launch of a Forfas science awareness programme, Mr Ahern said the report was a good report.
He said the comments by Mr Cullen were "about one aspect of the report".
"He is not the only minister who has debated fairly hotly some of the issues in it. We should be all big enough to take some of the criticisms," Mr Ahern said.
Mr Cullen said he had no intention of curtailing spending in the areas of housing and rural water, despite recommendations by the ESRI and he said he would pursue areas where spending was "absolutely essential".
The ESRI said a "no regrets" policy should be adopted in tackling Ireland's infrastructural deficit as set out in the National Development Plan but spending must be better targeted in the future.
In its mid-term evaluation of the NDP published today, the ESRI said the objectives of the plan were broadly correct but some details needed to be tweaked to account for the higher than expected costs hampering some projects and the requirements of the National Spatial Strategy.
The ESRI recommends that road building and public transport should take priority for the remainder of the plan but it stressed the need for more targeted project selection and a more rigorous cost/benefit analysis of projects.
Where plans are changed significantly as in Luas, the whole cost of the project should be reassessed, the ESRI said.
Mistakes were also made in the timing of road projects which led to cost overruns as the building sector struggled to raise capacity to keep up with scale of investments.
The ESRI does not explicitly call for a reduction in health spending but said further capital spending would be difficult to justify while beds in the health service remain empty due to lack of staff.
The institute also questions the logic of committing public money to service where 20 per cent of beds are called "private" or "semi-private" but the State pays half their cost.
The ESRI calls for abolition of tax breaks for private hospitals and the savings applied to the public health sector under the NDP.
The think tank sets out a number of initiatives to ensure a better return on investment. These include the abolition of tax reliefs and grants for housing which it says is driving house price inflation. It singled out the tax concessions for holiday homes which are inflating house prices in rural areas thus depriving locals of home ownership.
The cost of servicing these secondary homes is also draining resources away from more necessary projects and are in effect a subsidy for the wealthier professionals, according to Mr John Fitzgerald of the ESRI. Mr Fitzgerald questioned why the rest of the country should bare the cost of lighting the west Cork Riviera for the pleasure of a few.
Money could also be needlessly squandered on waste disposal under the current arrangement whereby regional authorities have responsibility for waste management. The ESRI recommended a centralised waste disposal system of two to three facilities is sufficient for a country of Ireland's size. Otherwise a plethora of smaller local waste disposal facilities paid for by the taxpayer could cost anything up to euro2.5 billion, the ESRI said.