Abstract

Merricks’s Overdetermination Argument against the existence of baseballs depends essen-tially on the following premise: BB Whenever a baseball causes an event, the baseball’s constituent atoms also cause that event, and the baseball is causally irrelevant to whether those atoms cause that event. This argument can be transformed into an argument against the existence of human organ-isms by replacing BB with HO Whenever a human organism causes an event, the human organism’s constituent atoms also cause that event, and the human organism is causally irrelevant to whether those atoms cause that event. Since Merricks believes in human organisms, he needs to explain why the considerations that support BB do not support HO equally well. What is the relevant disanalogy between hypothetical baseballs and hypothetical human organisms? Merricks’s answer to this question is this: If baseballs exist, all the facts about them are metaphysically determined by the microphysical facts. By contrast, human organisms, if