One approach to understanding low productivity that I find interesting is covered in Jason Furman's very readable "Is This Time Different? The Opportunities and Challenges of Artificial Intelligence" report [1] -- he's one of Obama's lead economists.

In short, productivity growth may be lagging because of AI etc; it's because people have to spend time retraining for jobs not obsoleted by new technologies. He briefly states his rejection of Gordon.

[1] https://www.whitehouse.gov/sites/default/files/page/files/20...