MECE (mutually exclusive, collectively exhaustive)

MECE (Mutually Exclusive, Collectively Exhaustive) is a principle for organizing ideas into categories that do not overlap and do not leave gaps. Developed by McKinsey, MECE helps break complex problems down into clear, complete, and non-redundant parts.

MECE is most useful at the outlining stage of writing. Start by identifying the core question your article must answer. Then list every component required to answer it fully — nothing more, nothing less. Each section should cover a distinct part of the problem, with no overlap (mutually exclusive), and together, the sections should fully address the topic (collectively exhaustive).

If your article repeats the same idea in multiple sections, it isn’t mutually exclusive. If it skips an obvious step or leaves part of the question unanswered, it isn’t collectively exhaustive.