Economists urge caution in debate over stagnation

There is "growing evidence of socioeconomic decay" as the US economy struggles, Gordon said, pointing to the rise in the prison population and "the enormous increase in the number of children born outside of wedlock".

He said that the US economy will be held back by slow growth both of productivity and the labor force.

"The fruits of the third industrial revolution" in information technology "may be coming to an end", said Gordon, who is a member of the economic panel that dates the start and finish of US recessions.

The productivity of non-farm business workers has risen an average 1 percent per year since the start of 2010, less than half the rate over the past 15 years, according to data from the Labor Department in Washington.

There has certainly been secular stagnation when it comes to the average, inflation-adjusted earnings of households, which have been essentially flat since around 2000, Robert Hall of Stanford University in California told the conference.

Hall, who heads the recession-dating panel of the National Bureau of Economic Research, highlighted the drop in labor-force participation and said much of the decline has occurred in upper-income households.