The Peter Principle is one of my favourite books. I try to read it once a year.

The principle explains perfectly why and how people tend to rise in organizations beyond their level of competency - into their level of incompetency.

What many label “success” is actually the final placement in this model of incompetence, which is precisely why success in a hierarchy is not correlated with happiness or productivity.

Understanding the Peter principle allows us to avoid being promoted beyond our competency, or of avoiding the worst symptoms of “final placement syndrome” if we have already reached our level of incompetence.

This is a 50 year old book, but organizations and promotions style function the same way. Having organizations filled with people at their level of incompetence ensures inefficiency in the system. 

We can do better.

I do also recommend the follow-up book The Peter Prescription, but The Peter Principle is definitely mandatory reading.