The tragedy of the commons is an economic and ecological concept concerning situations where private parties will overuse a common resource because private incentives and public interests aren't aligned. For example, overfishing or carbon emissions.

In this case, the problem as articulated in this article is that each party in the AI gold rush - Google, OpenAI, Baidu, etc - has an incentive to rush their AI development without adequate controls so they can get ahead of their competitors, potentially taking us into dangerous outcomes in which one of them produces AI that has far-reaching harmful consequences for humanity. I guess the 'commons' here is the future of human society, which AI developers have private incentives to take for granted.

The solution proposed is to adopt many of the classic solutions economists have devised for tragedies of the commons - points 1-8 in the article - and apply them to AI development in the ways set out in the article.