An Open Letter to Ezra Klein

Dear Mr. Klein:

You allege that when unemployment is high, a slowing of productivity growth is "good news" for the economy ("When bad economic news is good news," May 6).  The reason, according to you, is that the greater the number of workers required to produce a given amount of output – everything from a Starbucks' latte to a Boeing 747 – the higher is the is the demand for workers.

The relationship between productivity and demand for workers isn't this simple.  (If your employer, the...