Online Papers - Brian Weatherson

David Lewis 89
7.6 Applied Metaphysics
There’s much more that could be said about Lewis’s contributions to philosophy, but
we’ll end with a discussion of two wonderful pieces of applied metaphysics.
In “The Paradoxes of Time Travel” (1976a), 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.
“Holes” (Lewis and Lewis, 1970) was co-written with Stephanie Lewis. In it they
discuss, in dialog form, some of the metaphysical issues that holes generate. One of
the characters, Argle, wants to eliminate holes from his ontology, and the paper goes
over what costs must be met to make this form of nominalism work. The other character,
Bargle, pushes Argle to clarify his commitments, and in doing so draws out
many details of the nominalist framework. The case is of some interest in itself, but
it is also, as the authors note at the end, a useful case-study in the kind of moves nominalists
can make in eliminating unwanted ontology, and the costs of those moves.
Each paper can be, and indeed often has been, used for introducing complicated
metaphysical issues to students. The papers are, like many of Lewis’s papers, widely
anthologised. They are both excellent illustrations of the fact that, as well as being a
wonderful philosopher, Lewis was one of the best philosophical writers of his time.