Thanks to falling unemployment, rising home values, and record stock prices, an emerging consensus of forecasters, market participants, and policymakers has now concluded that the US consumer is finally back.

Don't believe it. First, consider the facts: Over the 21 quarters since the beginning of 2008, real - inflation-adjusted - personal consumption has risen at an average annual rate of just 0.9 percent. That is by far the most protracted period of weakness in real US consumer demand since the end of World War II and a massive slowdown from the pre-crisis pace of 3.6 percent from 1996 to 2007.

With household consumption accounting for about 70 percent of the US economy, that 2.7 percentage point gap has been enough to knock 1.9 percentage points off the post-crisis trend in real GDP growth. Look no further for the cause of the unacceptably high US unemployment.