Peter Principle

Peter Principle states that in a hierarchy, members are promoted based on success in their current role, so a competent person keeps rising until they reach a role they're not competent at — at which point promotions stop, because the criterion that drove every prior promotion, success in the current job, is no longer being met. Laurence Peter formulated it as satire in 1969, but the underlying mechanism is a real and fairly mundane consequence of how promotion criteria typically work.

The failure is baked into the evaluation method rather than any individual's ambition: an organization promotes someone for doing their current job well, which is evidence about that job, not about the different job one level up. A brilliant individual contributor is promoted to managing other engineers because they were the best engineer, but managing is a substantially different skill — people development, prioritization across a team, communicating upward — that the promotion criterion never actually tested. If they're bad at the new role, there's usually no further promotion to bail them out, and no formal mechanism to demote them back to the role they were excellent at, so they simply plateau in the role that exposed the gap.

The corollary, sometimes called the "Peter Plateau," is that a stable organization's org chart is, in some statistical sense, mostly staffed by people at or near their personal ceiling — the ones still succeeding haven't yet been promoted into the role that will stop them. This is a systemic argument, not a claim about any specific manager, and it's worth separating from a simpler explanation like Hanlon's Razor would suggest: nobody has to be foolish or political for this outcome to occur, it's what promoting-on-current-performance produces by default.

The corrective some organizations use is a dual ladder — letting technical seniority advance without requiring a move into management — which works precisely because it stops treating "good at the current job" as the only signal for what the next job should be.