Archive for March, 2014

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Why the Law of Likelihood Applies Only to Mutually Exclusive Hypotheses

March 20, 2014

Greg Gandenberger

Abstract: The Law of Likelihood is the central thesis of likelihoodism, one of three major schools of thought about the notion of evidence in science (Sober, 2008, Ch. 1). It says that datum E favors hypothesis H1 over H2 if and only if the likelihood function k = Pr(E|H1)/Pr(E|H2) > 1, in which case k measures the degree of that favoring. I propose to restrict the Law of Likelihood to mutually exclusive hypotheses. This proposal seems natural and suffices to block a counterexample due to Fitelson (2007, 476- 7), but it faces at least three significant objections: (1) it conflicts with plausible constraints on the notion of evidential favoring, (2) it fails to address the tacking paradox, and (3) it seems to exclude cases involving competing causal claims and cases involving nested models. I respond to each of those objections.

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Axiomatic Quantum Field Theory in the Philosophy of Quantum Field Theory

March 14, 2014

Bihui Li

Abstract: The philosophy of quantum field theory (QFT) in North America is dominated by philosophers working in the algebraic QFT tradition. They justify their choice of this tradition by a methodological requirement that when philosophers of physics study a theory T, the referent of T must be some mathematically well-defined structure. At the same time, philosophers think that their preferred axiomatic versions of QFT are best suited for “foundational”, “fundamental”, or “ontological” inquiries. I argue that the mathematical structures satisfying the methodological requirement are not always the best starting points for foundational, fundamental, or ontological inquiries. Many foundational, fundamental, and ontological questions are best addressed by constructive QFT, which starts with the ill-defined formalisms of Lagrangian QFT and tries to make them well-defined.  Because different interactions in constructive QFT require different mathematical constructions, the mathematical structures required cannot be determined prior to constructing a solution for a particular interaction. In contrast, the advantage of axiomatic QFT is its independence from the specific interactions being modeled, but this independence also means that it cannot provide many kinds of foundational, fundamental, or ontological information.

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Idealization of scales of motion in atmospheric dynamics

March 14, 2014
Marina Baldissera Pacchetti
Abstract: I discuss the use of idealizations as descriptions in climate science, especially in dynamical models of stable systems in the atmosphere. I contrast two accounts of idealizations. The first account is one in which idealizations are departures from the target system that can be dispensed of for obtaining a more accurate description of said system.  According to the second account, idealizations are ineliminable. I use various examples from atmospheric dynamics to argue that qualitative organizational features of various atmospheric systems can only be described in terms of ineliminable idealizations.
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Scientific Collaborations

March 7, 2014

Haixin Dang