This year 160,000 people enrolled in a Stanford online artificial intelligence course (HT: Chris Blattman). While those that completed the course received a certificate including their rank in the class, they didn't get any credit from Stanford. Why did so many people enroll?
My own prior is that tertiary education performs three roles: consumption, signaling, and training. Education is consumption because it is fun to learn new things, particularly if those things are presented well. A signaling aspect of college is necessary to explain why employers are willing to pay a large premium for a humanities major over a mere high school graduate. There is training in college as well. After four years of term papers I was able to write down my thoughts without embarrassing myself.
So which apply: Is the Stanford certificate worth something on the labor market, is it fun to learn AI basics from a couple of top researchers, or is there some productive use for the course material?