Introduction: Décio Krause, Quantum Mechanics, Non-individuality, and This Volume

Décio Krause, Jonas R. Becker Arenhart

Jonas R. Becker Arenhart, Raoni Wohnrath Arroyo

Christian DE RONDE, Ivan Klarreich

In this work we address the contemporary debate about quantum individuality expressed as an opposition between those who, like Décio Krause, defend the reference of the theory to "non-individual particles", and those like Dennis Dieks, who propose instead to preserve the notion of "classical particle" as commonly applied by contemporary physicists. We will argue that these viewpoints rather than truly opposed share a common methodology which has helped to reinforce the doctrine of classical concepts that was imposed by Bohr and Dirac within the "standard" formulation --which remains the orthodox physical account of the theory of quanta. We will also discuss a recently proposed relativist yet objective relational account of quantum individuality [25] which, going back to Einstein's methodological approach, opens the doors to a completely new, truly realist understanding of quantum individuality.

Anna Marmodoro

Nick Huggett

Introduction In sections 6 and 7 of their paper in this volume, French and Rickles raise the question of the logical relations between the indistinguishability postulate (IP) and the various senses in which particles might fail to be individuals. In section 6 they refer to the convincing arguments of French and Redhead (1988) and of Butterfield (1993) that IP does not logically entail non-individuality, understood several ways – even though, as all seem to concede, there is something perverse about taking bosons and fermions to be individuals. Going the other way, the possibility of IP violating ‘quons’ (Greenberg, 1991) shows that if non-individuality is taken to mean the absence of continuous distinguishing trajectories, characteristic of standard quantum mechanics (QM), then non-individuality does not entail IP. Nor, as French and Rickles point out, do substance or haecceity views of individuality. But what if we conceive of individuality in terms of the Principle of the Identity of Indiscernibles (PII)? First, French and Redhead (1988) and Butterfield (1993) have given theorems showing that bosons and fermions violate PII, while the former have also demonstrated violations of PII in the case of a certain paraparticle state. But these cases, as I will explain (and as French and Rickles point out), cover just a very few of the possible kinds of quantum particles, and so for each kind the question arises as to whether it violates PII.

Robert P Crease, Delicia Antoinette Kamins, Paul Rubery