Beyond Componential Constitution in the Brain

Componential mechanism (Craver 2008) is an increasingly influential framework for understanding the norms of good explanation in neuroscience and beyond. Componential mechanism “construes explanation as a matter of decomposing systems into their parts and showing how those parts are organized together in such a way as to exhibit the explanandum phenomenon” (Craver 2008, p. 109). Although this clearly describes some instances of successful explanation, I argue here that as currently formulated the framework is too narrow to capture the full range of good mechanistic explanations in the neurosciences. The centerpiece of this essay is a case study of Starburst Amacrine Cells—a type of motion-sensitive cell in mammalian retina—for which function emerges from structure in a way that appears to violate the conditions specified by componential mechanism as currently conceived. I argue that the case of Starburst Amacrine Cells should move us to replace the notion of mechanistic componential constitution with a more general notion of enabling constraint. Introducing enabling constraints as a conceptual tool will allow us to capture and appropriately characterize a wider class of structure-function relationships in the brain and elsewhere.