Modal Realism and Actualism
If we analyze modality with possible worlds, are those worlds as real as the actual one? Modal realists say yes; actualists hold that only the actual world is concrete and reconstruct other worlds as abstract entities.
Definition
Modal realism is the view that non-actual possible worlds are concrete realities; actualism is the view that everything that exists is actual, so other worlds, if admitted, are abstract.
Scope
Covers Lewis's concrete modal realism and its counterpart theory, actualist and ersatzist alternatives, the indexical analysis of actuality, and arguments weighing the theoretical benefits of worlds against their ontological costs.
Core questions
- Are non-actual possible worlds concrete or abstract?
- What does it mean to say that our world is the actual one?
- Can actualism recover the benefits of possible-worlds analysis?
- Do trans-world individuals exist, or only counterparts?
Key concepts
- Modal realism
- Actualism
- Possibilism
- Counterpart theory
- Indexical actuality
- Ersatz world
Key theories
- Concrete modal realism and counterpart theory
- Lewis holds that all possible worlds are equally concrete; an individual exists in only one world and is represented in others by counterparts, similar individuals that ground its de re modal properties.
- Actualism and abstract worlds
- Plantinga and Adams hold that only the actual world is concrete, analyzing possible worlds as abstract objects such as maximal states of affairs or world-stories, so that everything there is, is actual.
History
After possible worlds proved theoretically fruitful, the question of their nature became pressing. Lewis defended their concrete reality in On the Plurality of Worlds (1986), drawing the 'incredulous stare'. Actualists such as Plantinga and Adams developed abstract conceptions of worlds and an indexical treatment of actuality as the dominant alternative.
Debates
- Do the benefits of modal realism justify its ontology?
- Lewis argues that only a plurality of concrete worlds yields a fully reductive theory of modality, accepting the ontological cost; actualists contend that abstract worlds deliver comparable benefits without positing other concrete universes.
Key figures
- David Lewis
- Alvin Plantinga
- Robert M. Adams
- Robert Stalnaker
- Saul Kripke
Related topics
Seminal works
- lewis1986
- plantinga1974
Frequently asked questions
- What is the 'incredulous stare' objection to modal realism?
- It is the common reaction that Lewis's claim that countless concrete worlds exist, containing talking donkeys and the like, is simply too incredible to believe. Lewis acknowledged the reaction but argued the theory's systematic benefits outweigh it.