The Architecture of Complexity

The companion paper to Simon's books already in the library. Here Simon argues that complex systems evolve faster when they are hierarchically modular — "nearly decomposable" — because subsystems can evolve independently without destroying the whole. This is the theoretical foundation for microservices, team topologies, and every modern argument about loose coupling, written three decades before any of those terms existed. Forty pages that explain more about organisational design than most contemporary books on the subject. For product people the paper settles a recurring debate: modularity is not an architectural preference but an evolutionary necessity — systems that lack it do not survive long enough to matter.