A primer on causal emergence

This primer sets out causal emergence: cases where macro-level modelling exhibits greater causal efficacy than micro-descriptions. It introduces effective information as a measure, shows how coarse-graining and intervention guide model selection across scales, and addresses common misunderstandings. Framed as a reply to criticism, it situates causal emergence within debates on reductionism and multiscale explanation, offering concrete examples and practical notes for applying the framework to complex systems and observed behaviour.