Debating the interpretation of the Burgess Shale fossil records, Stephen Jay Gould and Simon Conway Morris have formulated two conflicting theses regarding the nature of evolutionary processes. While Gould argued that evolution is essentially a contingent process whose outcomes are unpredictable, Conway Morris claimed that the omnipresence of convergence testifies that it is in fact deterministic, leading to predictable and inevitable outcomes. Their theses have been extensively researched from various perspectives. However, a systematic parallel analysis of the core arguments each (...) of them offered in support of their thesis has been lacking. I argue Conway Morris has successfully exposed the core weaknesses of Gould's thesis and offered a comprehensive account in favor of the major role of convergence in evolutionary history. On the other hand, I will point out some of the weak points in the latter's arguments supporting the deterministic view of life's evolution. Although Conway Morris has been more successful in arguing for the deterministic nature of the evolutionary processes, both theses could be improved if their shortcomings are taken into consideration. (shrink)

I develop an account of homology and homoplasy drawing on their use in biological inference and explanation. Biologists call on homology and homoplasy to infer character states, support adaptationist explanations, identify evolutionary novelties and hypothesize phylogenetic relationships. In these contexts, the concepts must be understood phylogenetically and kept separate: as they play divergent roles, overlap between the two ought to be avoided. I use these considerations to criticize an otherwise attractive view defended by Gould, Hall, and Ramsey & Peterson. By (...) this view, homology and homoplasy can only be delineated qua some level of description, and some homoplasies (parallelisms) are counted as homologous. I develop an account which retains the first, but rejects the second, aspect of that view. I then characterize parallelisms and convergences in terms of their causal role. By the Strict Continuity account, homology and homoplasy are defined phylogenetically and without overlaps, meeting my restriction. Convergence and parallelisms are defined as two types of homoplasy: convergent homoplasies are largely constrained by external factors, while parallelisms are due to internal constraints. (shrink)

‘Gouldian arguments’ appeal to the contingency of a scientific domain to establish that domain’s autonomy from some body of theory. For instance, pointing to evolutionary contingency, Stephen Jay Gould suggested that natural selection alone is insufficient to explain life on the macroevolutionary scale. In analysing contingency, philosophers have provided source-independent accounts, understanding how events and processes structure history without attending to the nature of those events and processes. But Gouldian Arguments require source-dependent notions of contingency. An account of contingency is (...) source-dependent when it is indexed to some pattern and some process. Positions like Gould’s do not turn on the mere fact of life’s contingency—that life’s shape could have been different due to its sensitivity to initial conditions, path-dependence or stochasticity. Rather, Gouldian arguments require that the contingency is due to particular kinds of processes: in this case, those which microevolutionary theory cannot account for. This source-dependent perspective clarifies both debates about the nature and importance of contingency, and empirical routes for testing Gould’s thesis. (shrink)