emergence

Emergence is a concept used across philosophy, physics, biology, and complex-system studies to describe properties or behaviors that appear at a higher level of organization than the components that compose a system. These higher-level features arise from interactions among parts and are not readily predictable from the properties of the individual components alone. The term was popularized in the late 19th century by George Henry Lewes to capture how organized complexity can yield novel phenomena.

There are two broad senses of emergence. Weak emergence refers to higher-level phenomena that, in principle, can be derived from lower-level rules, even if such derivations are computationally difficult or impractical. Strong emergence denotes higher-level properties that are said to be genuinely novel and not reducible to lower-level explanations, potentially requiring new laws or descriptions. In contemporary science, weak emergence is the more common framework for understanding macro-level patterns.

Common examples include flocking patterns in birds, traffic flow, and pattern formation in chemical and physical systems during phase transitions. Biological and social systems also display emergent organization, such as ant colonies, neural networks, and ecosystems. In the philosophy of mind, emergence is used to argue that consciousness may arise from neural processes, though this remains a topic of debate. Emergence is often explored through models like agent-based simulations and cellular automata, which show how simple local rules can produce complex global behavior.

Emergence complements reductionism by acknowledging that higher-level descriptions—patterns, laws, and behaviors—can be informative and robust even when micro-level details are known. It highlights nonlinear interactions, feedback, and organization as drivers of complex phenomena, a central concern in complexity science and systems theory.