émergence

Emergence (émergence in French) refers to the phenomenon whereby higher‑level properties, patterns, or behaviors arise from the interactions of a system’s components in ways that are not straightforwardly predictable from the properties of the parts alone. Emergent phenomena typically become evident only when many elements interact, producing regularities at a larger scale. Common examples include the coordinated motion of a bird flock, the spontaneous organization of chemical reactions, and the macro-scale properties of ecosystems. The term is used across philosophy, science, and engineering to describe patterns that arise from complexity rather than being explicitly engineered into individual elements.

Two broad notions are used in the literature: weak emergence and strong emergence. Weak emergence covers higher‑level phenomena that arise from lower‑level rules and can in principle be derived or simulated, though often with substantial computational effort. Strong emergence claims that certain higher‑level properties are genuinely novel and not deducible from subcomponent behavior, sometimes with causal powers that affect the parts. The distinction is debated, and some writers prefer terms such as supervenience or downward causation to articulate related ideas.

Emergence is discussed in philosophy of mind, physics, biology, economics, and computer science. In physics, phase transitions show macroscopic properties arising from microscopic interactions. In biology, developmental processes and ecological networks reveal emergent structure. In computer science and artificial intelligence, agent‑based models illustrate how simple local rules produce complex global behavior, such as flocking or traffic patterns. In neuroscience, the question of whether consciousness is an emergent property of neural activity remains a topic of debate.