He's referring to the Dunning-Kruger effect. When you’re incompetent, the skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is. In logical reasoning, in parenting, in management, problem solving, the skills you use to produce the right answer are exactly the same skills you use to evaluate the answer.
At work I'm in charge if IT and I'm the most cautious and conservative person when it comes to technology I'm not familiar with. I think that bothers some people but I can live with it. I try to be smart enough to know when I'm not smart enough to know.