Jessica Pfeifer- An Alternative Account of Objective Probabilities in Evolution

Jessica Pfeifer (University of Maryland, Baltimore County)

The Center for Philosophy of Science invites you to our Featured Former Fellow online lecture presented by:   

Featured Former Fellow:   Jessica Pfeifer

Friday, October 2nd @ 12:00 pm - 1:30 pm EST

Title:  An Alternative Account of Objective Probabilities in Evolution

Abstract: 

Strevens, Abrams, and Rosenthal have independently developed accounts of objective probability consistent with determinism grounded in the theory of arbitrary functions. In this talk, I focus on Strevens’ way of developing and describing the approach in terms of microconstancy and macroperiodicity. These accounts face (at least) two major problems: (1) the problem of initial conditions; and (2) the question of whether systems studied by scientists satisfy the conditions required for these accounts to work, in particular whether the systems are microconstant and macroperiodic.

The aim of the talk is to outline an alternative account of physical probability in a deterministic system that is grounded in the dynamics of that system, without requiring that the system is microconstant or macroperiodic, and without being dependent on the actual distribution of initial conditions in some form or other. Like Strevens, Abrams, and Rosenthal, I think objective probabilities in deterministic systems can be grounded in facts about the dynamics of the actual world. However, I argue that we should separate out what these facts entail about what would happen over a large class of possible outcomes from what happens in a large class of actual events. Physical probability first and foremost tells us about the former. We can only make inferences about the latter with additional assumptions or information (such as microconstancy, macroperiodicity, and facts about initial conditions). However, as I will show, the lack of the latter does not entail that objective probabilities have no significant role to play in science. I focus specifically on the use of probabilities in evolutionary theory. Based on an account I develop elsewhere, I argue that probabilities allow biologists to represent the causal difference between natural selection and random genetic drift, and that this has implications for what would happen over possible (and perhaps non-actual) conditions. Moreover, this allows us to distinguish different roles that probabilities can play in science and what is required for each. Some of these roles might require microconstancy and macroperiodicity, but others do not. The aim of the talk is to argue that there is a role that objective probabilities can play even when a system is not microconstant or macroperiodic.

This talk will be available online only:

Zoom:   https://pitt.zoom.us/j/91318992513

 YouTube at https://www.youtube.com/channel/UCrRp47ZMXD7NXO3a9Gyh2sg.