A former chief economist at the World Bank has said that austerity has "almost never" worked as a solution to economic downturns.
He said austerity instead turns downturns into recessions and plunges recessions into depressions.
Professor Joseph Stiglitz was speaking at the opening of the International Bar Association annual conference in Dublin.
The Nobel laureate in economics said there must either be more Europe, through a common banking system, or less Europe, through a partial eurozone breakup.
Prof Stiglitz said the present "half-way" position is not viable.
He warned that the speed of political change is currently too slow for economics and that Europe will stay in or near recession for "an extended period of time".
Former president Mary Robinson is also to address the conference.
About 5,000 legal professionals from around the world have travelled to Dublin to attend the week-long gathering.