This dynamism of our labor force strengthens the U.S. economy because each move to a new employer can involve greater responsibility, greater pay or both

Sure, and it can involve less pay, with less responsiblity, or more responsibility and less pay. And sure, when your in your twenties it can be fun to change jobs a couple of times. But it gets old pretty darn quick. Moreover, there is a huge status difference between the essentially long term temps working in many setting now and the few 'core' employees.

Of course, our gracious host can simply look at his own life. After the unfortunate events in Chicago, did he go looking for a series of untenured lectureships -- these can sometimes be quite lucrative, after all, if you string several together. Plus they provide flexibility to universities, enabling them to respond dynamically to the marketplace. Like "no Dan, we don't want you teaching International Institutions this year , put can you lecture a couple of sections on the history of Islamic diplomacy? Shouldn't take too long to read up on it."

No, methinks Dr Drezner, he really really wanted the job security (and status) that tenure involves.

And no, I am not nostaglic for the days of company men. I recognize that ontological security is a huge human need.

I think what worries people is that they will have about 10 different jobs between 45-65 ...

a bit of job churn early in your career is one thing (and i do think European systems train people too specifically for a given occupation/ make it hard to move around), but too much churn (especially of the involuntary kind) with kids and heath care concerns and the like is rather another, I would guess.

And if churn doesn't generate -- in the end -- better paying jobs, well, that does kind of change the equation. My sense is that a lot of the churn comes from the fact that folks working minimum wage style jobs basically quit and leave if they need to take time off, on the assumption that they kind find another that is about the same. I am not sure that is productivity enhancing.

"Even more striking is that, on average, workers in the United States will have 10 different employers between ages 18 and 38."

Is that so striking? It seems about right given the number of internships, casual summer gigs, etc., that a young person goes through, then the inevitable early-career job-hopping.

"In December, the average duration of a job search was the shortest in more than four years."

So, maybe the average duration of a job search is back where it was before the dot-com bust?

Faint praise?

This dynamism of our labor force strengthens the U.S. economy because each move to a new employer can involve greater responsibility, greater pay or both.

"Can". Not "does".