 In “The Paradoxes of Time Travel” (1976d), Lewis discusses the many complicated philosophical issues about  time travel.  He discusses  temporal parts,  personal identity, causation and causal loops, free will, and the complications arising from our many different modal concepts. In some cases he uses the canvas provided to illustrate his own take on the metaphysical issues that arise. But in some cases he notes that the problems that arise are problems for everyone.