Jim Rutt, a noted complexity theorist, defines 'hierarchical complexity' as the classification of tasks and actions based on the structure and interdependence of their component processes. According to Rutt, hierarchical complexity emphasizes the way simpler, foundational elements combine to form increasingly sophisticated systems, each layer building upon and encapsulating its predecessors. This framework allows for the differentiation of cognitive and behavioral tasks, from basic sensory responses to advanced problem-solving and abstraction. Rutt views this concept not only as essential for understanding individual and social behaviors but also as fundamental for analyzing the evolution of complex systems in both natural and artificial domains. Through hierarchical complexity, Rutt provides a lens to view how entities evolve, adapt, and function across various levels of sophistication and interrelation.

See also: complexity science, emergence, evolutionary computing, evolution