Edward Halper’s three volume One and Many in Aristotle’s 'Metaphysics' contends that Aristotle argues for his central metaphysical doctrines by showing that they alone resolve various versions of what is known as “the problem of the one and the many.” The present volume, Alpha–Delta, argues that these books constitute the first stage of Aristotle’s inquiry, his case for the existence of metaphysics. Halper shows that the possibility of metaphysics turns on its having a subject matter with a sufficient degree of unity to be known by one science. Although books Alpha–Delta address the problem that occupied Aristotle’s predecessors, they also prepare the way for—and are consistent with—the second stage, the inquiry into principles in the central books. Along the way Halper argues for unique interpretations of “being qua being,” the source of the aporiai, the method of “saving the phenomena,” “said in many ways,” the principle of non-contradiction, and the significance of book Delta.