A pluralistic (mosaic) approach to causality in health complexity

There is an increasing appreciation in the health sciences that the health of populations involves complex systems. Health complexity requires a re-orientation of health research and the nature of interventions, acknowledging key features of complex systems such as emergence, feedback loops, interactions, and adaptation. Causality is a central notion in the health sciences, but how should causality be understood in complex systems, specifically in the context of population health? In this chapter, we argue that a causal mosaic approach to thinking about and using causal concepts is appropriate for answering this question because it helps us see how causal relations are studied and how they are intervened upon using a plurality of methods. The phrase 'causal mosaic' should not be understood as referring to a plurality of causal factors preceding an outcome, but rather to the plurality of concepts available for thinking about causality. We show how causality can be incorporated and remain central as complex science approaches are developed in population health.