that U.S. growth is insufficient to reach full employment: "Suppose then that the short term real interest rate that was consistent with full employment [i.e., the "natural rate"] had fallen to negative two or negative three percent. Even with artificial stimulus to demand you wouldn't see any excess demand. Even with a resumption in normal credit conditions you would have a lot of difficulty getting back to full employment." Robert J. Gordon wrote in August 2012: "Even if innovation were to continue into the future at the rate of the two decades before 2007, the U.S. faces six headwinds that are in the process of dragging long-term growth to half or less of the 1.9 percent annual rate experienced between 1860 and 2007. These include demography, education, inequality, globalization, energy/environment, and the overhang of consumer and government debt. A provocative 'exercise in subtraction' suggests that future growth in consumption per capita for the bottom 99 percent of the income distribution could fall below 0.5 percent per year for an extended period of decades". Post-2009 Secular stagnation was dusted off by Hans-Werner Sinn in a 2009 article dismissing the threat of inflation, and became popular again when Larry Summers invoked the term and concept during a 2013 speech at the IMF. However, The Economist criticizes secular stagnation as "a baggy concept, arguably too capacious for its own good". Warnings of impending secular stagnation have been issued after all deep recessions, but turned out to be wrong because they underestimated the potential of existing technologies. Paul Krugman, writing in 2014, clarified that it refers to "the claim that underlying changes in the economy, such as slowing growth in the working-age population, have made episodes like the past five years in Europe and the United States, and the last 20 years in Japan, likely to happen often. That is, we will often find ourselves facing persistent shortfalls of demand, which can’t be overcome even with near-zero interest rates." At its root is "the problem of building consumer demand at a time when people are less motivated to spend". One theory is that the boost in growth by the internet and technological advancement in computers of the new economy does not measure up to the boost caused by the great inventions of the past. An example of such a great invention is the assembly line production method of Fordism. The general form of the