Here's one clue to the continuing sluggishness of the American economy: Historically, when the economy grew by $1 million, it created about 10 jobs. Thus, with GDP growing by $134.6 billion in the first quarter of 2012, you would have expected 1,344,600 new jobs.

Instead only 590,000 new jobs were created. Each million dollars in added output created 4.4 jobs, not 10. Some experts are warning that it is going to get worse, with perhaps only one or two jobs added for every million-dollar increment.

Computers will do the work instead.

In an important article in The McKinsey Quarterly last fall, W. Brian Arthur, a fellow at the Santa Fe Institute and former professor of economics at Stanford University, suggested that a 'second economy" is emerging in the United States, and indeed, worldwide. The second economy requires very few people; business is transacted among computers.

"If I were to look for adjectives to describe this second economy," Arthur wrote, "I'd say it is vast, silent, connected, unseen and autonomous (meaning that human beings may design it but are not directly involved in running it). It is remotely executing and global, always on, and endlessly configurable. It is concurrent — a great computer expression — which means that everything happens in parallel. It is self-configuring, meaning it constantly reconfigures itself on the fly, and increasingly it is also self-organizing, self-architecting, and self-healing."

Brian Arthur, 67, pioneered something called "complexity theory," which operates at the intersection of economics, mathematics and technology. His 2009 book, "The Nature of Technology," is a sacred text in Silicon Valley.

His work supports the theory that the 2007-2009 recession, the 2008 financial collapse and enduring high unemployment are far different from the usual cyclical economic slowdown. These events did not create structural change in the economy, but with cheap credit no longer available to mask the problems, they may have revealed it.

Dealing with structural change will require stronger and different medicine than that prescribed so far by either President Barack Obama and the Federal Reserve or presumptive Republican presidential nominee Mitt Romney and his allies in Congress.

"Is this the biggest change since the Industrial Revolution?" Arthur wrote. "Well, without sticking my neck out too much, I believe so. In fact, I think it may well be the biggest change ever in the economy. It is a deep qualitative change that is bringing intelligent, automatic response to the economy. There's no upper limit to this, no place where it has to end ... it would be easy to underestimate the degree to which this is going to make a difference."

The problem with the second economy, he writes, is that it produces prosperity without jobs:

"The second economy will produce wealth no matter what we do; distributing that wealth has become the main problem. For centuries, wealth has traditionally been apportioned in the West through jobs, and jobs have always been forthcoming. When farm jobs disappeared, we still had manufacturing jobs, and when these disappeared we migrated to service jobs. With this digital transformation, this last repository of jobs is shrinking — fewer of us in the future may have white-collar business process jobs — and we face a problem."

Listen carefully this summer and fall: If a candidate mentions "jobs" and not "the second economy," he has no clue.

REPRINTED FROM THE ST. LOUIS POST-DISPATCH