These days 'evolution' is usually defined as any change in the relative frequencies of genes in a population over time. This definition and some obvious alternatives are examined and rejected. The criticism of these definitions points out the need for a more holistic analysis of genotypes. I attempt such analysis by introducing measures of similarity of whole genotypes and then by grouping genotypes into similarity classes. Three sorts of measures of similarity are examined: a measure of structural similarity, a measure (...) of functional similarity and one of relational or historical similarity. The functional approach is shown to be superior and a definition of 'evolution' is suggested. (shrink)

Many philosophers have asserted that evolutionary theory is unfalsifiable. In this paper I refute these assertions by detailing some falsifiable predictions of the theory and the evidence used to test them. I then analyze both these predictions and evidence cited to support assertions of unfalsifiability in order to show both what type of predictions are possible and why it has been so difficult to spot them. The conclusion is that the apparent logical peculiarity of evolutionary theory is not a property (...) of evolutionary theory; it is a property of our human-sized perspective on evolutionary theory. (shrink)

In this paper I attempt to show that adaptational sentences (i.e. sentences containing the terms "adaptive", "adapted", etc.) in evolutionary biology are best interpreted as equivalent to sentences about Darwinian or genetical selection. Thus, the use of adaptational languages does not introduce final purposes or other nonempirical notions into biology. I also try to demonstrate that adaptational sentences and functional sentences are not equivalent in an evolutionary context so that an analysis of function does not dispense with the need for (...) an analysis of adaptation. Finally, it is argued that, although some adaptational sentences might be construed as teleological explanations, given an empirical content, they do not serve as explanations. Rather, they express the outcome of selection, regarded in one way, and regarded in another, they express data for which a theory of evolution must account. (shrink)