David Lewis published a seminal paper on time travel in 1976, called 'The Paradoxes of Time Travel'. It is a foundational piece that has impacted later discussions of time travel in analytic metaphysics. The paper was read at the APA in March 1976. His commentator was...

David Lewis was a contented atheist. He was adamant that he would never be converted. Throughout his career as he discussed topics of religion with other philosophers he realised that he would never convert his opponents either. Despite this, he thought there was...

This month’s letter — from Lewis to Tony Coady — is a bit of light relief from abstract philosophising. Lewis is worrying about testimony, and in particular worrying about whether or to what extent someone’s known past deception affects, or should affect, whether we...

In February’s letter of the month, Lewis responds to Stewart Cohen’s 1998 article ‘Contextualist Solutions to Epistemological Problems: Scepticism, Gettier, and the Lottery’, Australasian Journal of Philosophy 76 (2):289 – 306. Lewis accepts the suggestion that the...

One area of philosophy that Lewis had an impact on was epistemology. But, unlike other areas he influenced, his writings on epistemology derive from just one article, namely, his widely read 1996 'Elusive Knowledge', Australasian Journal of Philosophy vol. 74. It is...

December’s letter of the month is to Paul Fitzgerald, a peer of David Lewis at Harvard University who wrote his thesis on the metaphysics of time under Donald C. Williams. This letter is in reaction to Fitzgerald’s The Truth About Tomorrow's Sea Fight. 1969. Journal...

Lewis and Vagueness (guest post, by Daniel Nolan, University of Notre Dame) This month's letter is an eleven-page letter David Lewis sent to Timothy Williamson in May 1999. The letter divides into three main sections. In the first, Lewis sets out his own views about...

In ‘New Work for a Theory of Universals’ and ‘Putnam’s Paradox’ Lewis famously argued that Putnam’s model-theoretic argument against realism fails. His response to Putnam is that there is a real division between natural and non-natural properties out there in the...

Soon after the publication of Gareth Evans’s classic one-page Analysis paper on vagueness in 1978, Lewis was struck by how many misunderstood what Evans was up to. He wrote several letters about this issue. His letter to Allen Hazen, 15 November 1978, led to Lewis’s...

Lewis’s recipient - John Coker - was a student of Alvin Plantinga at Notre Dame in the 1980s. Coker wrote a paper arguing that modal realism, with Lewis’s added trappings of concrete worlds, no overlap, qualified principle of recombination, etc, is atheististic in the...

In this letter, Lewis provides comments on a draft of Colin McGinn’s 1980 Functionalism and Phenomenalism: A Critical Note. Australasian Journal of Philosophy 58 (March):35-46. This letter is important for understanding Lewis’s theory of mind but also for...

In this letter to Solomon, Lewis reflects on disagreement in philosophy and ascribing mental states to turkeys. Disagreement in Logic and Philosophy Lewis believes that philosophical disagreements often reach a deadlock where neither side will move. Lewis here points...

In this letter to Follesdal, Lewis presents an early draft of his famous theory of counterparts. Do Possible Worlds Exist? Famously, Lewis believed in the existence of infinitely many physical possible universes. Lewis had been an early adopter of modal logic. Such...

In this letter to Wellesley philosopher Mary Kate McGowan, Lewis discusses causation, explanation, and conceptual analysis in connection with dispositions. Classification, dispositions, and conceptual analysis Lewis tells McGowan that he thinks to have a concept of x...

In this letter to Quine Lewis discusses Quine's contribution to the appendix of Lewis's set theory book, Parts of Classes. Summary of Letter Lewis argued, in Parts of Classes, for the equation: set theory = mereology + plural quantification + the singleton function....

This 1971 letter to Mondadori contains an early version of Lewis's reply to the famous problem now known as the 'Humphrey objection'. In the first paragraph, Lewis agrees to publish ‘Languages and Language’ in Italian. It duly came out in 1973 as 'Lingue e lingua'...

Lewis here comments on two key issues: reference and methodology. In this letter, Lewis's assesses the debate between him and Putnam about reference. Putnam had taken a pessimistic line on the question how words connect to their worldly referents. In short,...

In this letter David Lewis argues against Reinhardt Grossmann's claim that logic is about states of affairs (or facts), and not about sentences or propositions. It is an interesting example of Lewis's opposition to factualist ontologies and his steadfast commitment to...

This month's letter is from 1984 and sees Lewis asking the cartoonist Roz Chast whether she will allow him to use her 'Parallel Universes' cartoon as the frontispiece for On the Plurality of Worlds. Chast said 'no' since she was about to use it as the cover for her...