Overdetermination and Elimination

Abstract

I focus on two arguments, due to Jaegwon Kim and Trenton Merricks, that move from claims about the sufficiency of one class of causes to the reduction or elimination of another class of entity, via claims about overdetermination. I argue that in order to validate their move from sufficiency to reduction or elimination, both Kim and Merricks must assume that there can be no ‘weak overdetermination’; i.e., that no single effect can have numerically distinct but dependently sufficient causes occurring at the same time. One problem for both arguments is that weak overdetermination isn't obviously objectionable. That point has been well made before. But I want here to go further than merely shifting the burden of proof onto the advocates of overdetermination arguments. I want to tease out why they are so convinced that we must resist weak overdetermination and explain why their conviction is misguided. Both Merricks and Kim, I shall argue, ultimately rest their case on the same motivating principle, which I call the principle of additional causal powers. This principle, I argue further, should be rejected. It lacks argumentative support, and it begs the question against those at whom the arguments are directed.