The summer's most talked about working paper in economics is by Robert Gordon, and it is simply titled “Is US Economic Growth Over?” And well he might ask: GDP per capita, the most obvious measure of economic growth, is lower today than it was when the financial crisis began in 2007.

The western world's failure to recover from the crisis surely explains why Gordon's gloomy thesis is getting so much attention, but, in fact, he takes great pains to avoid drawing conclusions from any short-term difficulties - even if the short term has now lasted more than half a decade.

Gordon has been arguing since the days of the dotcom mania that the information revolution looks rather puny compared with earlier waves of innovation, such as the internal combustion engine, indoor plumbing, electrification and the telephone - all of which took hold from about 1850 to 1900. This claim was plausible then and it's plausible now. (Would you rather give up the smartphone, Facebook and broadband - or hot running water and your flush toilet?)