Jonathan Lowe argues that metaphysics should be restored to a central position in philosophy, as the most fundamental form of rational inquiry, whose findings underpin those of all other disciplines. He portrays metaphysics as charting the possibilities of existence, by identifying the categories of being and the relations of ontological dependency between entities of different categories. He proceeds to set out a unified and original metaphysical system: he defends a substanceontology, according to which the existence of the world as one world in time depends upon the existence of persisting