Mass Additivity and A Priori Entailment

TL;DR

This paper examines the principle of mass additivity, its validity in different physical theories, and explores how philosophical theories of reduction can accommodate its explanation, with implications for understanding consciousness.

Contribution

It offers a novel philosophical reconstruction of mass additivity explanations that aligns with modern theories of reduction, bridging physics and philosophy.

Findings

Mass additivity holds in Newtonian mechanics but not in special relativity.

A philosophical reconstruction can incorporate mass additivity explanations within reductive theories.

Implications for reductive explanations of consciousness are discussed.

Abstract

The principle of mass additivity states that the mass of a composite object is the sum of the masses of its elementary components. Mass additivity is true in Newtonian mechanics but false in special relativity. Physicists have explained why mass additivity is true in Newtonian mechanics by reducing it to Newton's microphysical laws. This reductive explanation does not fit well with deducibility theories of reductive explanation such as the modern Nagelian theory of reduction, and the a priori entailment theory of reduction that is prominent in the philosophy of mind. Nonetheless, I argue that a reconstruction of the explanation that incorporates distinctively philosophical concepts in fact fits both theories. I discuss the implications of this result for both theories and for the reductive explanation of consciousness.