Requisite Variety (Ashby's Law)

W. Ross Ashby's cybernetic law: a controller must have at least as much variety (range of responses) as the system it's trying to control. A thermostat with only on/off can control temperature to a range; one with variable output can control it precisely. Applied to management: a leader with only one leadership style (command-and-control) cannot effectively manage a team that requires multiple approaches (mentoring, coaching, delegating, directing). An organization with a single strategy cannot navigate an environment that presents multiple types of challenges. Requisite variety demands that your response repertoire match the complexity of your environment.

When to use it

When management approaches aren't working despite being 'right' for some situations (they may lack variety for the full range of situations); when organizations struggle with environmental complexity; when designing systems that need to handle diverse inputs; when leadership development needs a framework for what capabilities to build.

How it can help

Audit the variety gap: how complex is the environment you're managing, and does your response repertoire match? If your market is highly variable but your strategy is monolithic, you lack requisite variety. If your team has diverse needs but your management style is uniform, you lack requisite variety. The interventions: (1) Expand your response repertoire (learn new skills, strategies, approaches). (2) Reduce environmental variety to match your capacity (simplify, focus, choose markets you can handle). (3) Build organizational variety through diverse teams, decentralized decision-making, and flexible processes.