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Tight and Loose Coupling

Why It Matters

Coupling determines failure modes. Tight coupling enables efficiency but creates catastrophic risk. Loose coupling sacrifices efficiency for resilience.

The Key Move

Ask: how fast do changes propagate? How much slack exists between components? Tight coupling looks like: just-in-time dependencies, no buffer inventory, synchronous processes. Loose coupling looks like: buffers, queues, asynchronous processes, slack resources.

Classic Application

Nuclear power plants. Tightly coupled systems where failures cascade faster than humans can respond. Small problems become large disasters.

Surprising Application

Organization design. Tightly coupled teams (many dependencies, synchronous work) are efficient when things go well but fragile to disruption. Loosely coupled teams (autonomous, async, buffered handoffs) sacrifice coordination efficiency for resilience.

Failure Modes

  • Tightening coupling for efficiency without recognizing increased fragility
  • Assuming loose coupling means no coordination
  • Missing that coupling can be asymmetric (tight in one direction, loose in another)

Go Deeper

Perrow's "Normal Accidents." High-reliability organization literature.