Spontaneous contexts: Explanatory diversity in biological self-assembly

In this paper, I argue that explaining spontaneous phenomena in biology requires multiple types of scientific explanations. First, I contend that explaining spontaneity necessitates citing both topological and nomological features as explanans. Second, I assert that the context-sensitivity of spontaneity complicates mechanistic localization, necessitating the inclusion of functional and network features to account for mechanistic operations. To develop this argument, I present two models of activated self-assembly and their roles in explaining two cases of biological structures: virus capsids and microtubule dynamics. This approach reveals a complex explanatory landscape that spans multiple levels of generality. I term this structure of explanations an "explanatory reservoir."