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.