Multi-Level Selection and the Explanatory Value of Mathematical Decompositions

Domulti-level selection explanations of the evolutionof social traits deepen the understanding provided by single-level explanations? Central tomultilevel explanations is a mathematical theorem, the multi-level Price decomposition. I build a framework through which to understand the explanatory role of such non-empirical decompositions in scienti c practice. Applying this general framework to the present case places two tasks on the agenda. e rst task is to distinguish the variousways bywhich onemight suppresswithin-collective variation in tness, or indeedbetween-collective variation in tness. I distinguish ve such ways: increasing retaliatory capacity; homogenising assortment; collapsing either tness structure or character distribution to a mean value; and boosting tness uniformly within collectives. I then evaluate the biological interest of each of these hypothetical interventions. e second task is to discover whether one of the right-hand terms of the Price decomposition measures the effect of any of these interventions. On this basis I argue that themulti-level Price decomposition has explanatory value primarily when the sharing-out of collective resources is ‘subtractable’. us its value is more circumscribed than its champions Sober andWilson ([1998]) suppose. 1 Single-Level andMulti-Level Selection 2 ree Conditions on Explanatory Decompositions 3 e Multi-Level Price Decomposition 4 e Biological Interest Problem for Sober andWilson ∗Forthcoming 2014/2015. ismanuscriptwas created July 23, 2014— e content is identical to the copy submitted for nal proo ng.