More on the genetical theory of multilevel selection

In my article The genetical theory of multilevel selection, I provided a synthesis of the theory of multilevel selection (MLS) and the theory of natural selection in class-structured populations. I framed this synthesis within Fisher’s genetical paradigm, taking a strictly genetical approach to traits and fitness. I showed that this resolves a number of longstanding conceptual problems that have plagued the MLS literature, including the issues of “aggregate” versus “emergent” group traits, “collective-fitness1” versus “collective-fitness2” and “MLS1” versus “MLS2”. In his commentary, Goodnight suggests this theoretical and conceptual synthesis is flawed in several respects. Here, I show this is incorrect, by: reiterating the theoretical and conceptual goals of my synthesis; clarifying that my genetical approach to traits is necessary for a proper analysis of the action of MLS independently of non-Darwinian factors; emphasising that the Price-Hamilton approach to MLS is consistent, useful and conceptually superior; and explaining the role of reproductive value in the study of natural selection in class-structured populations