David Lewis

1941-2001 · American · Metaphysics, Philosophy of Language, Philosophy of Mind, Epistemology, Philosophy of Science

There are ever so many ways that a world might be; and one of these many ways is the way that this world is.

When David Lewis published On the Plurality of Worlds in 1986, most philosophers greeted it with what he cheerfully called the incredulous stare. His claim: the other possible worlds are just as real and concrete as this one, populated by their own stars, people, and quarks, causally sealed off from us. Lewis meant it literally, and defended it not by arguing it was intuitive but by arguing it was worth the price.

Topics David Lewis addresses

modal realism
counterpart theory
the incredulous stare
Humean supervenience
the Humean mosaic
perfectly natural properties
the abundant/sparse distinction
the Best System Analysis of laws
the counterfactual analysis of causation
counterfactual dependence
causation as influence
small miracles and quasi-miracles
the Principal Principle
finkish dispositions
mad pain and Martian pain
analytic functionalism
realizer functionalism
the Lewis-Nemirow ability hypothesis
convention as game-theoretic coordination
common knowledge
truthfulness and trust in L
the rule of accommodation
scorekeeping in a language game
epistemic contextualism

Questions to put to David Lewis

Modal Realism and Counterpart Theory

What do you mean when you say other possible worlds are as real as this one?
Why think possible worlds are concrete rather than abstract representations?
How does counterpart theory work, and why not just say the same object exists in many worlds?
What's your answer to the incredulous stare?
How do you respond to the worry that modal realism is just too extravagant to believe?

Humean Supervenience and the Mosaic

What is the Humean mosaic, and what does it mean for everything to supervene on it?
What are perfectly natural properties, and how do they carve nature at its joints?
How can laws of nature just be patterns in the mosaic rather than something that governs it?
What would you say if quantum entanglement turns out to violate Humean supervenience?
Why defend Humean supervenience as tenability rather than truth?

Causation, Counterfactuals, and Laws

How does your counterfactual analysis of causation work?
What's the difference between your 1973 chain-of-dependence view and the 2000 causation-as-influence revision?
How do you evaluate counterfactuals using similarity of worlds?
What is the Best System Analysis of laws, and why not think laws necessitate their instances?
How can a law here depend on patterns elsewhere in the cosmos?

Mind, Qualia, and Psychophysical Identity

What's the difference between your type-type identity view and standard functionalism?
How does the Mad Pain and Martian Pain case support relativizing identity to populations?
What does Mary the color scientist gain when she leaves the black-and-white room?
Why think she gains new abilities rather than new propositional knowledge?
How do you use the Ramsey-Carnap-Lewis method to define mental states?

Convention, Language, and Coordination

What makes a regularity a convention rather than just a habit or coincidence?
How does your game-theoretic analysis of convention work?
What are the conventions of truthfulness and trust in a language?
How can a language be the language of a population without anyone agreeing to use it that way?
What role does common knowledge play in sustaining conventions?

Mereology, Persistence, and Vagueness

Why accept unrestricted mereological composition—that any objects whatsoever compose a further object?
What is the problem of temporary intrinsics, and how do temporal parts solve it?
What's the difference between perduring and enduring through time?
How does your contextualist treatment of vagueness work in scorekeeping?
What is the rule of accommodation, and how does it apply to knowledge claims?

Converse with David Lewis on Simposeum. Replies are grounded in David Lewis's own writing, cited to the page.