Natural Selection, Mechanism, and Fitness: A Response to Wei

In contemporary biology and philosophy of biology, there remains a lack of consensus regarding the nature of natural selection. Over recent decades, a wide variety of interpretations and approaches to natural selection have been proposed. In a recent paper, Wei (Citation2024, “Natural Selection, Mechanism and Phenomenon.” International Studies in the Philosophy of Science 37:37–50.) critically examines current mechanistic accounts of natural selection. For this purpose, he focuses on a particular aspect of the mechanistic approach: a mechanism is always a mechanism for a phenomenon. Wei introduces two criteria that the phenomenon assigned to natural selection should fulfil and, on this basis, evaluates phenomena previously considered. Contrary to Pérez-González and Luque (Citation2019, “Evolutionary Causes as Mechanisms: A Critical Analysis.” History and Philosophy of the Life Sciences 41:13.), Wei argues that the increase in the frequency of fitter traits cannot be considered the phenomenon for which natural selection is responsible. The aim of this paper is to analyse and engage with Wei’s critique. We contend that his arguments face significant challenges and do not substantially weaken the assignment of increasing the frequency of fitter traits.