The Dow set a new high Tuesday, but the larger economy is a different story. What if today’s sluggish economic growth turns out to be the new normal? That’s the unsettling question asked by some of our most creative economic thinkers. 

And the people asking it are not necessarily partisan opponents of the Obama administration. They argue that economic growth rates were disappointing even before the financial collapse and recession of 2007-09. 

Take Tyler Cowen, author of the e-book (belatedly published in print) “The Great Stagnation.” Economic growth is the product of increases in the labor supply and productivity, he argues uncontroversially.