ABSTRACT
This article focuses on utilitarian issues in the free will versus determinism controversy, proposing three psychological principles to guide daily practice. The principle of behavioral supplementarity states that behavior is the joint result of explainable and unexplainable causes. The principle of remote antecedence states that psychologically more remote causation produces a greater proportion of the unexplainable behaviors. The principle of complementarity states that both the explainable and the unexplainable causes can be understood in terms of two discrepant conceptual systems—voluntarism and determinism—which are analogous to the two mutually exclusive conceptions of a reversible figure. I proposed that both views reflect equally valid conceptions of realities. The relative utilities of these systems are related to the psychological remoteness of the causation, with more remote causation favoring the voluntaristic mode of thinking.