Goodhart's Law
Goodhart's Law states that when a measure becomes a target, it ceases to be a good measure. Originally formulated by British economist Charles Goodhart in the context of monetary policy, it is one of the most important and underappreciated principles in management, policy design, and artificial intelligence. It explains why metrics get gamed, why KPI culture often produces perverse outcomes, and why AI systems misaligned with actual goals can behave destructively.