Parthood and Composition in Quantum Mechanics

Gregg S. Jaeger

Phil Pickering, Sam Baron, John Tanner

The goal of this paper is to outline a viable notion of parthood for vectors. The importance of vector parthood has come to the fore in discussions of quantum mechanics, with two accounts existing already. We show that both fail to preserve the transitivity of parthood. We thus present a new account of vector parthood that preserves transitivity and is applicable to quantum systems. We close by suggesting some applications for the notion we present here that go beyond quantum mechanics, including ordinary sinusoidal waves (e.g., water or sound waves).

Tim Maudlin

Phil Pickering, Sam Baron, John Tanner

This paper outlines a notion of parthood for vectors, which has come to the fore in discussions of quantum mechanics. We show that existing accounts fail to generalise in a way that preserves transitivity. We thus present a new more general account that preserves transitivity and is applicable to quantum systems but may have applicability beyond quantum mechanics, including classical vector quantities and waves.

Isaac Wilhelm

I propose and defend an analysis of the parthood relation among quantum wavefunctions. Roughly put, according to the analysis, one wavefunction is part of another just in case the latter can be projected onto the former. This analysis brings mereology into closer contact with contemporary physics, implies many standard mereological principles, challenges some traditional mereological presuppositions, and supports compelling answers to long-standing questions about parthood.

A. Mangoni