معرفت فلسفی

This paper examines the circularity challenge inherent in the definition of “fitness” from the standpoint of the explanatory value of natural selection in evolutionary theory. The fundamental issue arises from the fact that fitness is often defined in a circular manner without offering an independent criterion. In other words, employing the statement “those that survive are the fitted ones” without specifying the precise causal factors for survival transforms natural selection into a tautology: “those that survive are those that survive.” Initially, the paper reviews the historical background and the conceptual position of fitness in Darwin’s work, regarding the efforts of earlier biologists in formulating evolutionary theory. It then thoroughly examines the criticisms raised by philosophers and biologists such as Popper and Brandon. Subsequent sections analyze Elliott Sober’s response to this tautology challenge, in which he proposes a probabilistic propensity interpretation of fitness—incorporating viability and fertility components—to establish a causal formulation. However, the analysis reveals that even Sober’s proposal regarding the causal role of variety in fitness within evolution faces significant challenges, ultimately leaving his response inconclusive.