Abstract

Developments in the sequencing of whole genomes and in simultaneously surveying many thousands of transcription and translation products of specific cells have ushered in a conceptual revolution in genetics that rationally introduces top-down, holistic analyses. This emphasized the futility of attempts to reduce genes to structurally discrete entities along the genome, and the need to return to Johannsen's definition of a gene as 'something' that refers to an invariant entity of inheritance and development. We may view genes either as generic terms for units of inheritance whose referents are pragmatic ad hoc and context-dependent, or as (epistemologically) representing entities of cell functions. It is cellular functions that determine the structural referents along the DNA. Structures that happened to secure specific functions that were essential for or conducive to the survival of cells were selected for. With natural selection being the etiological background of genes as functions, genes obtain again their theoretical role as intervening variables, abstractive variables that purely 'summarize' characters. The importance of DNA sequences is that of all possible phenotypes these are the most basic ones from which we can read off the genotype directly.