Jens Rasmussen

Jens Rasmussen (1926–2017) was a Danish engineer and cognitive systems theorist whose work on human factors, cognitive systems engineering, and risk management shaped the modern understanding of how operators interact with complex technological systems. His "abstraction hierarchy" framework provided a method for analyzing the functional structure of complex systems across multiple levels — from physical form to abstract purpose — and his work on boundary violations and the "drift to failure" anticipated later developments in resilience engineering.

Rasmussen's most influential contribution was the recognition that human operators in complex systems are not unreliable components but adaptive agents who respond to local pressures and system constraints. His work provided the theoretical foundation for understanding accidents as the result of systemic drift rather than individual error.