Or maybe the culprit is a corollary of Moore’s Law, the idea of exponential advances in technology over time. That might suggest that innovation and automation displace more and more workers by the time each recession rolls around.
This is also Marshall Brain's thesis in Robotic Nation:
http://www.marshallbrain.com/robotic-nation.htm
In the broadest terms, automation and computerization increase productivity, which means fewer people are needed to do the same amount of work. Conventional wisdom holds that new jobs will be created for displaced workers, but it's as yet unclear what those new jobs might be.