Does Elementary Classical Mechanics Obey the Principle of the Composition of Causes?
Sheldon Smith, UCLA
At least part of what Bertrand Russell was claiming in “On the Notion of Cause” was that 1) physics appeals to mathematical equations that don't obviously tolerate an interpretation in terms of causation and 2) when one nonetheless describes the content of those equations using causal vocabulary, one introduces “misleading associations.” The most familiar example of this phenomenon occurs when one describes an initial condition of a time reversal invariant differential equation as a “cause”, thus introducing associations of time asymmetry that are not present in the equation. I want in this paper to give a novel example of the introduction of such misleading associations by causal vocabulary. Specifically, I will argue that the “Principle of Composition of Causes” --- the way some describe the summation of forces used in derivations of differential equations of motion in classical point-particle mechanics --- introduces misleading associations that have led some to make errors. Moreover, I will argue that those errors trace to the causal vocabulary in which the principle is stated.