Teleology is a philosophical view which ascribes the changes and direction of phenomena or events to final causes or previously existing plans, purposes, or ends. This can be contrasted to causality where changes in phenomena are determined by the unfolding of the laws of nature. Teleology played a crucial role in the work of Ludwig von Mises especially in the development of his science of praxeology. More specifically he believed that human action, i.e. purposeful behavior, is teleological based on the presupposition that an individual's action is governed or caused by the existence of their chosen ends. Or in other words an individual selects the most appropriate means to achieve a sought after goal or end. Mises's however also stressed that teleology with respect to human action was by no means independent of causality as he states "no action can be devised and ventured upon without definte ideas about the relation of cause and effect, teleology preupposes causality".