November & December 2019 Lunchtime Abstracts & Details

Squaring the Extrapolator’s Circle 
Jonathan Fuller, U. Pittsburgh, Dept. of HPS
Tuesday, November 5, 2019
12:05 pm, 1117 Cathedral of Learning

Abstract: To explain or predict the effect of some exposure in a human target population, health scientists and social scientists often extrapolate from a study done on some other human or non-human population. This procedure is used frequently in toxicology and epidemiology, where the exposure is a potential toxin or carcinogen, the outcome is a disease such as cancer and the study is an animal experiment. In these situations, extrapolators often use information about the exposure’s mechanism of action. In so doing, they must confront the extrapolator’s circle, the problem of how information about the mechanism could be used to extrapolate from the study without that information already containing the conclusion one is extrapolating. Steel (2008, 2010) explores the extrapolator’s circle and proposes a selective comparative process tracing as a solution, in which the extrapolator compares the study and the target population to see if the mechanism is undisrupted at certain stages in order to extrapolate the conclusion that the exposure is causally relevant. Steel’s solution fails to escape the extrapolator’s circle but points the way towards a successful strategy. I will illustrate using the example of aflatoxin B1, which causes liver cancer in rats and is an occasional food contaminant leading to exposure in people. The illustration may even shed light on whether you yourself should be worried about aflatoxin exposure! 

Baroque Mathematics
Paolo Palmieri, U. Pittsburgh, Dept. of HPS
Tuesday, November 12, 2019
12:05 pm, 1117 Cathedral of Learning

Abstract: In this talk I conjure, or evoke by supernatural power, or jugglery, the emergence of early modern calculus, the geometry of indivisibles, in confrontation with the ghost of Archimedes, the wonders of Baroque aesthetics, rhetoric, and the estranging creative power of extenuated metaphor.

On the Analogy Between Electric Charge and Color Charge
Marian Gilton, U. Pittsburgh, Dept. of HPS
Tuesday, November 19, 2019
12:05 pm, 1117 Cathedral of Learning

Abstract: Philosophers and physicists alike introduce color charge as a new kind of charge that is like electric charge. There is good reason for this. It makes good sense to begin with the case of electric charge in the simpler theory of electromagnetism and then introduce the more complicated theory of chromodynamics and its associated color charge in reference to what is already understood from the simpler theory. Moreover, the theorists who first constructed chromodynamics did so with a conscious effort to generalize the methods of electromagnetism. However, it is often unclear how exactly the analogy between electric charge and color charge is supposed to go. Electric charge is measured in laboratories; it is given in positive and negative rational numbers; it is gauge invariant. None of these features apply to the properties of red, blue, and green (as well as their anti-charge counterparts) that we usually think of as color charge. In this talk, Gilton will argue that the color charge properties of red, blue, and green have no analog in electromagnetism. Instead, an analogy between electric charge and color charge can be recovered by considering the more general notions of ‘having electric charge at all’ and ‘having color charge at all.’

Isolated Systems and Their Symmetries
David Wallace, U. Pittsburgh, Dept. of Phil & HPS
Tuesday, December 3, 2019
12:05 pm, 1117 Cathedral of Learning

Abstract: I provide a fairly systematic analysis of when quantities that are variant under a dynamical symmetry transformation should be regarded as unobservable, or redundant, or unreal; of when models related by a dynamical symmetry transformation represent the same state of affairs; and of when mathematical structure that is variant under a dynamical symmetry transformation should be regarded as surplus. A central feature of the analysis is that in order to draw any of these conclusions for a dynamical symmetry it needs to be understood in terms of its possible extensions to other physical systems, in particular to measurement devices; as such, I also consider the implications for the interpretation of symmetries of systems of the application of symmetry transformations to subsystems of those same systems.