International Society for History, Philosophy, and Social Studies of Biology

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MONDAY, JULY 6  /  15:30 - 17:00  /  DS-M220
Organized session / standard talks
Formal epistemology and evolutionary biology

Bengt Autzen (University of Bristol, United Kingdom)

Evolutionary biology raises a number of epistemological questions: How to test hypotheses about natural selection? How to infer evolutionary history? And, how to combine evidence from different sources? Formal epistemology has equipped philosophers with a number of tools to address these and other issues in evolutionary biology. The symposium will present current philosophical work at the intersection of the two disciplines. The purpose of the symposium is twofold. First, the session aims to provide new insights into epistemological problems in both Darwin’s work and in contemporary biological research by applying formal methods. Second, the symposium will discuss conceptual issues arising from the application of formal methods to biological questions. That is, by applying formal methods to particular inference problems we can explore the implications and possible limitations of these techniques.

Is natural selection evidence for common ancestry?

Elliott Sober (University of Wisconsin-Madison, United States); Mike Steel (University of Canterbury, New Zealand)

Darwin thought that natural selection explains why all present-day life traces back to one or a few common ancestors. Here we investigate whether natural selection increases the probability of Darwin’s thesis about common ancestry. We show that any such claim of probability raising is indefensible. We develop our argument by identifying the property of an evolutionary process that determines what its probabilistic impact on the common ancestry thesis will be. The point of this exercise is to understand how the parts of Darwin’s powerful theory fit together, not to call into question common ancestry or natural selection, as these enjoy strong support.

Judgement aggregation and phylogenetics

Joel Velasco (Texas Tech University, United States)

Traditionally, phylogenetic inference has assumed as a background that there are unique histories for the particular taxa, species, organisms, or genes that you are examining. When you have multiple sources of evidence such as data from multiple genes, one possible class of methods for inferring that history is to treat the genes independently and try to aggregate the results in some manner. The realization that different genes quite often have different histories makes aggregation methods simultaneously more important if you are trying to build a unique tree and also less important since it opens up the possibility that we shouldn’t be building a single tree at all. In this talk I will compare the situation in phylogenetics and in other aggregation contexts such as social choice theory and group deliberation to see what connections can be drawn and what can be learned from these connections and importantly, also how these contexts differ and why that matters.

Dissolving the star tree paradox in Bayesian phylogenetics

Bengt Autzen (University of Bristol, United Kingdom)

While Bayesian methods are widely used in phylogenetic systematics today, the foundations of this methodology are still debated among both biologists and philosophers. The ‘star tree paradox’ in Bayesian phylogenetics refers to the phenomenon that a particular binary phylogenetic tree sometimes has a very high posterior probability even though a star tree generates the data. In this paper I discuss two proposals found in the biological literature of how to solve the star tree paradox. In particular, I defend the polytomy prior against some objections raised by biologists and argue that it is preferable to Yang’s data-size dependent prior from a methodological perspective.