In Chapter 9 we present and defend a causal account of multilevel mechanistic explanation by examining various case studies from biology. We argue that two key consequences of Causal Mechanism are (1) that levels and mechanisms are distinct notions and (2) that levels of multilevel explanations are levels of composition. This view is in stark contrast to Craver’s account, according to which levels in multilevel explanations are levels of mechanisms and multilevel explanations are instances of constitutive explanations. A key claim of the chapter is that whatever contributes to the phenomenon is part of the same pathway; but causal pathways can contain entities from multiple levels of composition. In order to motivate and illustrate our view, we use various examples from biology and medicine. We criticise some common views associated with the picture of a hierarchy of mechanistic levels and argue that our view allows for causation at higher levels.

In this introductory chapter, we outline some conceptual building blocks for an ecosocial view of the co-construction of mind, brain, and culture. The brain is the organ of culture; mind and experience are processes located in loops of active engagement of brain and body with the social world. This engagement occurs on multiple time scales, from evolution and co-evolutionary adaptation to humanly designed niches, through the cultural history of populations and communities, to individual developmental trajectories, narratives of the self, and moment-to-moment engagements with social contexts. We are born biologically equipped to acquire culture and, across our lifespan, we become attuned to particular social and cultural environments. The niches we inhabit are cooperatively constructed and presented to us as cultural affordances that enable our cognitive capacities, sense of self, adaptive skills, and meaning-making capacity. The rewiring of brain circuits, synaptic plasticity, and underlying changes in gene regulation only make sense in relation to the particular resources, affordances, and adaptive tasks presented to us by specific cultural environments. Answering the question of what makes us human then turns out to involve not just an evolutionary story in deep time, but also cultural and individual stories in historical, developmental, and biographical time.

In this epilogue, we reflect on the prospects for advancing interdisciplinarity in the sciences of culture, mind, and brain. Neuroscience is increasingly applied to address questions of central concern to the social sciences. Social sciences, in turn, can contribute to neuroscience research in a variety of ways, including: (1) the study of social factors that influence the brain across the lifespan; (2) the context-sensitive translation of neuroscience research into applications in clinical and other social settings; (3) critical social analyses of cultural, conceptual, and institutional framing and constraints on neuroscience research, knowledge production, and applications; and (4) integration of each of these approaches in an ecosocial view of the brain in its social-cultural niche. Obstacles to interdisciplinarity stem from institutional structures, methodological strategies, epistemic commitments, and divergent ontologies. We describe strategies to surmount these obstacles, including: (1) institutionally, creating spaces for collaborative work, supporting interdisciplinary career tracks, and ensuring sustained funding; (2) conceptually, borrowing models and metaphors across disciplines, establishing boundary objects of common interest, using system diagrams to locate diverse levels and processes in the same model; and (3) methodologically, establishing convergent validity through mixed and hybrid methods, and creating shared databases and pipelines to facilitate integration of multiple perspectives.