A common criticism of punctuated equilibria as an evolutionary theory is that it erects a straw man by characterizing the modern synthesis as being devoid of mechanisms that bring about rapid speciation and abrupt changes in morphology. Thompson supports this view and argues that the modern synthesis does not entail gradualism, all-pervasive adaptationism, or extrapolationism and that punctuationists have mischaracterized the theory on all these points; properly understood the synthetic theory is hierarchical and able to explain phenomena at all levels (...) of the hierarchy, thus rendering macroevolutionary theories, such as punctuated equilibria, unnecessary. I argue in this paper that Thompson's approach is overly dependent upon rational reconstruction in the style of the logical empiricists, and as such ignores important sociological and historical factors that when taken into account justify punctuational criticism of the synthetic theory. (shrink)

A review of Paul Thompson's semantic interpretation of evolutionary theory.

The conflation of two fundamentally distinct issues has generated serious confusion in the philosophical and biological literature concerning the units of selection. The questions of how a unit of selection is defined, theoretically, is rarely distinguished from the question of how to determine the empirical accuracy of claims--either specific or general--concerning which unit(s) are undergoing selection processes. In this paper, I begin by refining a definition of the unit of selection, first presented by William Wimsatt, that is grounded in the (...) structure of natural selection models. I then explore the implications of this definition for empirical evaluation of group selection models. I examine an objection to Wimsatt’s definition raised by Elliott Sober, and I conclude by indicating how the proposed refined definition can clarify which sorts of empirical evidence could be brought to bear on group selection controversies. (shrink)

Weak links, in the form of inadequacies in both reasoning and supporting evidence, exist at several critical steps in the derivation of an hierarchical concept of evolution from punctuated equilibria. Punctuation itself is predicated on a distorted reading of phyletic change as phyletic gradualism, and of allopatric speciation as the instantaneous formation of unchanging typological taxa. The concept of punctuation is further confounded by the indescriminate employment of the same term to denote both a causal explanation for evolutionary change and (...) an outcome of substantiated evolutionary processes. Even when the intended usage for the term is specified, each denotation of punctuation entails respective drawbacks. As a causal explanation, punctuation clearly belongs to the class of quantum theories with all their attendant impedimenta, including special salsatory non-adaptive mechanisms of evolutionary change. Redefinition of punctuation as a pattern of morphologic change reduces it to one possible outcome of known microevolutioanry processes, thus obviating any need for an hierarchical explanation of macroevolution. While vacillation between usages has preserved the term in the literature, the end result of this obfuscation has been a circle of faulty reasoning in which the pattern of punctuation is invoked as its own proof. Widespread confusion concerning what constitutes an adequate test of punctuation is directly attributable to imprecision in both the original and revised formulations of the concept.The argument for species-level selection is based on the typological and philosphically flawed premise of species as individuals, and further requires the hypothesis of heritable emergent properties, for which empirical evidence is lacking. (shrink)

Why has it been so difficult to integrate paleontology and mainstream evolutionary biology? Two common answers are: (1) the two fields have fundamentally different aims, and (2) the tensions arise out of disciplinary squabbles for funding and prestige. This paper examines the role of fossil data in phylogeny reconstruction in order to assess these two explanations. I argue that while cladistics has provided a framework within which to integrate fossil character data, the stratigraphic (temporal) component of fossil data has been (...) harder to integrate. A close examination of how fossil data have been used in phylogeny reconstruction suggests that neither explanation is adequate. While some of the tensions between the fields may be intellectual turf wars, the second explanation downplays the genuine difficulty of combining the distinctive data of the two fields. Furthermore, it is simply not the case that the two fields pursue completely distinct aims. Systematists do disagree about precisely how to represent phylogeny (e.g., minimalist cladograms or trees with varying levels of detail) but given that every tree presupposes a pattern of branching (a cladogram), these aims are not completely distinct. The central problem has been developing methods that allow scientists to incorporate the distinctive bodies of data generated by these two fields. Further case studies will be required to determine if this explanation holds for other areas of interaction between paleontology and neontology. (shrink)