The prevailing world depression, the enormous anomaly of unemployment in a world full of wants, the disastrous mistakes we have made, blind us to what is going on under the surface to the true interpretation of the trend of things. For I predict that both of the two opposed errors of pessimism which now make so much noise in the world will be proved wrong in our own time-the pessimism of the revolutionaries who think that things are so bad that nothing can save us but violent change, and the pessimism of the reactionaries who consider the balance of our economic and social life so precarious that we must risk no experiments.as J.M. Keynes wrote in "Economic Possibilities for Our Grandchildren" (1931).*
The rise in living standards over time - the long-run growth rate - depends on labor productivity (i.e., output per hour of work). That, in turn, depends on capital per worker and technological progress (broadly defined as our ability to wring more output from a given amount of capital and labor). Since capital has diminishing returns, it is really technological progress that ultimately matters.
At his Conversable Economist blog, Tim Taylor notes that growth in per capita real GDP over the past two centuries in the US has been remarkably consistent in the long run. Using Measuring Worth's series, it looks like this:
Technological progress essentially determines the slope, and a seemingly small rate of change, compounded over a few decades, is a big deal - a much bigger deal, measured in output, than the "great recession" (whether output is the right thing to count is another, more complicated, matter). So it may be cause for concern that productivity growth, after picking up in from the mid-1990's through the early 2000's, appears to have slowed again.
Average TFP growth rates, US Private Sector (source: BLS)
The New Yorker's John Cassidy has some interesting musings on why that might be. The alarming possibility is that the productivity resurgence associated with the internet is petering out already. However, in the short-run, productivity measurements can be volatile and affected by business cycles, so its we may want to hold off on worrying that the trend has turned down.
*I'd actually started writing this and
**If anyone knows of a graphing program that easily does a nice job with log scales, I'd love to hear about it (the ones Excel makes don't come out very well and I'm repeatedly aggravated by trying).