Vito Balorda

In the debate on causal explanation in biology, in the past two decades largely influenced by the new mechanist approach, the concept of a pathway has recently reemerged as a promising research agenda, 551-572, 2018; The British Journal for the Philosophy of Science, 72, 131-158, 2021). Ross’ account of biological explanation differentiates several autonomous types of causal structures that play explanatory and other roles across the life sciences. NM, however, prioritizes mechanisms as vehicles of biological explanations. According to this program, the causal architecture of biological pathways and other causal structures, such as cascades and processes, can be interpreted with at least one of the NM’s mechanism concepts. In other words, these alternative causal structures are not sufficiently distinctive to merit the explanatory autonomy with regard to the NM corresponding concepts. We examine the explanatory practice of molecular biology and concur with Ross that there are indeed distinct types of causal structures, not all falling under the concept of a mechanism. Nonetheless, we show that the concept of mechanism is referring to a privileged causal structure, at the center of explanatory efforts in molecular biology. Pathways and other causal concepts, while somewhat distinct from mechanisms themselves, are explanatorily relevant to the degree in which they exhibit mechanistic features, are parts of a mechanistic architecture, or may lead to a mechanistic arrangement. What emerges in that manner is a hierarchy of causal structures with mechanisms at the explanatory top, and lower levels differing in the degree in which they contribute to mechanistic arrangements.

In this paper, we examine the issue of characterizing natural selection. Usually, natural selection is characterized as a force, as a statistical concept, and as a certain causal structure (e.g., a mechanism). We focus on the characterization of natural selection as a mechanism, and, considering the unsettled debate on the issue, particularly in the light of new mechanistic accounts, argue for a pathway characterization. We examine this issue by addressing the following three questions: (i) how does a strategic consideration of mechanisms, according to which, roughly, is methodologically best to give primacy to the cognitive-epistemic power of mechanistic modelling and scientific methods even in evolutionary biology, relate to the extant interpretations of natural selection as a mechanism? (ii) Which part of the process of natural selection could be, if at all, characterized as a pathway, specifically, considering pathway’s strategic aspect, i.e., its modelling and methods? Accordingly, (iii) how do the concepts of mechanism and pathway relate to each other in this domain? In the present paper, we address primarily the first two questions. Thus, with regard to (i), we examine the characterization of natural selection as a mechanism. In particular, we apply the strategic consideration of mechanisms to other types of causal structures as well, such as that of a pathway. That discussion leads us to addressing question (ii), and to some extent (iii), where we argue that certain stages of natural selection conform to specific strategic pathway features.