Placeholders

Abstract

Black boxes are placeholders. What is a placeholder? What role do they play in science? These questions are addressed via a discussion of biological fitness. Fitness is the propensity of an organism or a trait to survive and reproduce. In addition, fitness is a placeholder for a deeper account that dispenses with the concept of fitness altogether. These two theses are in tension. Qua placeholder, fitness is explanatory. Qua disposition, it explicates but cannot explain the associated behavior. The solution involves drawing a distinction between two kinds of placeholders. First, a placeholder may stand in for the range of events to be accounted for. In this case, the placeholder functions as a frame. It spells out a range of behaviors in need of explanation. Second, a placeholder may stand in for mechanisms which bring about the behavior specified by the frame. When this occurs, the placeholder becomes an explanans and one can refer to it as a difference-maker.