Peter's principle, also known as the upward climbing principle, is a conclusion drawn by American scholar Lawrence Peter based on the analysis of thousands of incompetent failures in relevant organizations, that is, in various organizations, because they are used to promoting people who are competent at a certain level, employees always tend to be promoted to their incompetent position.
According to the above definition, Li's appointment as a middle manager because of his father-in-law's position in the company, but his inability to do the job due to a lack of experience, conforms to Peter's principle.