Ethics is central to the project of humanity, that is, the project of the humanization of our world. Ethical life, central as it is to human praxis, hinges on the possibility of freedom. The concept of human nature as a complex dynamic system points to a level of explanation that makes freedom, empathy, and reason possible, without having to avail ourselves of metaphysical, or nonnatural, entities such as the soul or the mind. If materialism is to be successful, it must be shown that freedom is indeed possible. The starting point of Kant's conception of freedom is the paradox that freedom is the absence of natural causation, yet no action is possible without its being the effect of natural determination; all action is after all a set of events in the natural world. Materialists have been beset by a major difficulty: materialism is committed to a determinist view of the world, which, it would appear, is incompatible with freedom.