Phil-Convos

Dialogue with David Lewis

David Lewis icon

David Lewis

1941–2001

Modal Realism, Counterpart Theory, Metaphysics

American philosopher known for modal realism, counterpart theory, and Humean supervenience.

Philosophical Contributions

  • Modal Realism: All possible worlds are equally real concrete entities
  • Counterpart Theory: Objects in different worlds are counterparts rather than identical
  • Humean Supervenience: All facts about the world supervene on the arrangement of local qualities
  • Conventions and Language: Language meaning emerges from conventions in communities
  • Counterfactuals: Counterfactual analysis of causation

Dialogue with David Lewis

This chatbot draws from Lewis' seminal works including On the Plurality of Worlds and Counterfactuals. Ask about:

  • Modal Realism: Are all possible worlds equally real?
  • Counterpart Theory: How do objects exist across different worlds?
  • Humean Supervenience: How do properties emerge from arrangements?
  • Conventions: How do linguistic conventions determine meaning?

The chatbot uses concepts, arguments, and examples from Lewis' works to engage with you.

Thought Experiments

Modal Realism

Consider a world where everything is identical to ours except that one atom is positioned differently. Is that world less real than ours?

Counterpart Theory

If you exist in multiple possible worlds, are you identical across worlds or are you a counterpart?

Example: In world W1, you are a philosopher. In world W2, you are a musician. Are these the same person or counterparts?

Humean Supervenience

Imagine a world with exactly the same distribution of atoms as ours but with different laws of nature. Is this possible?

Conventional Meaning

If everyone in a community uses "green" to refer to red objects, does "green" mean red in that community?

Dialogue Interface

David Lewis Now
I'd like to begin with a fundamental question about reality - what do you make of the claim that all possible worlds are equally real?
David Lewis Now
The standard view is that only our world is real, while other worlds are merely possibilities. I argue that all possible worlds are concrete entities, just as real as our world, but spatiotemporally disconnected from us.
David Lewis Now
This leads to counterpart theory: objects in different worlds are counterparts rather than identical persons. A counterpart relation is based on qualitative similarity rather than identity across worlds.

Key Concepts to Explore

Modal Realism

The view that all possible worlds are equally real concrete entities.

Counterpart Theory

The theory that objects in different worlds are counterparts rather than identical.

Humean Supervenience

The doctrine that all facts about the world supervene on the arrangement of local qualities.

Conventions

The view that language meaning emerges from conventions in communities.