Fisher’s Fundamental Theorem of Natural Selection—A Philosophical Analysis

This paper provides a philosophical analysis of the ongoing controversy surrounding R.A. Fisher’s famous ‘fundamental theorem’ of natural selection. The difference between the ‘traditional’ and ‘modern’ interpretations of the theorem is explained. I argue that proponents of the modern interpretation have captured Fisher’s intended meaning correctly and shown that the theorem is mathematically correct, pace the traditional consensus. However, whether the theorem has any real biological significance remains an unresolved issue. I argue that the answer depends on whether we accept Fisher’s nonstandard notion of environmental change, on which the theorem rests; arguments for and against this notion are explored. I suggest that there is a close link between Fisher’s fundamental theorem and the modern ‘gene’s eye’ view of evolution.