Abstract: "In this talk, I will give an overview of the debate on whether Leibniz's Principle of the Identity of Indiscernibles (PII), according to which qualitative difference is necessary for numerical difference, is violated by similar particles (like, e.g., two electrons). According to so-called orthodox views, PII is always violated or, at best, valid in a weak sense only. According to heterodox views, however, (a strong version of) PII is valid for similar particles in at least some cases. The main motivation for heterodox views is that orthodox arguments for the violation of PII (tacitly) rely on a certain background assumption - called factorism - which can be questioned from a physical point of view. Factorism is a semantical view concerning the quantum mechanical formalism; more specifically, it is the view that indices within this formalism have physical (not just mathematical) meaning. However, factorism yields some implausible consequences; e.g., according to one prominent argument, it hinders quantum particles from becoming localized in the classical limit. Another important concept on which heterodox views rely is a certain understanding of entanglement - called GMW-entanglement, because it goes back to physicists Ghirardi, Marinatto and Weber - which is argued to fit better for similar particles than the usual understanding in terms of non-factorizability. Since heterodox views are relatively recent, they suffer from a problem - the so-called ambiguity problem - to which a complete and satisfying solution is yet to be found. The ambiguity problem shows that individuation via properties (i.e., what heterodox views want to accomplish on an ontological level) is not unique, i.e., ambiguous. I will discuss different aspects of the ambiguity problem and propose some potential solutions".
The PoP-Grunch (Philosophy of Physics Graduate Lunch) is a weekly informal seminar in which graduate students in Philosophy of Physics present their work in progress.
Philosophy of Physics Graduate Lunch Seminar Convenor: Eleanor March, Bryan Cheng and Paolo Faglia
