Micro-Macro Link

The micro-macro link is the explanatory gap between individual-level behavior and collective-level outcomes in social, biological, and economic systems. It is the central methodological problem of agent-based modelling and the conceptual bottleneck that prevents bottom-up theories from achieving general predictive power. The link is not merely a technical challenge but an ontological one: what level of aggregation preserves causal relevance, and what level dissolves into statistical noise? Sociology calls this the structure-agency problem; economics calls it the representative-agent problem; biology calls it the unit-of-selection problem. These are not different problems — they are the same micro-macro link viewed from different disciplinary shores. The field remains fragmented because no general formalism has emerged that can translate across all three domains. Recent attempts to formalize the link have drawn on social physics and computational social science, but no consensus framework has emerged.