Concept
Modal realism
Overview
Modal realism is the view propounded by the philosopher David Lewis that all possible worlds are real in the same way as is the actual world: they are "of a kind with this world of ours." It states that possible worlds exist, possible worlds are not different in kind from the actual world, possible worlds are irreducible entities, and the term actual in actual world is indexical, i.e. any subject can declare their world to be the actual one, much as they label the place they are "here" and the time they are "now".
Extended modal realism is a form of modal realism that involves ontological commitments not just to possible worlds but also to impossible worlds. Objects are conceived as being spread out in the modal dimension, i.e., as having not just spatial and temporal parts but also modal parts. This contrasts with Lewis' modal realism, according to which each object only inhabits one possible world.
Common arguments for modal realism refer to their theoretical usefulness for modal reasoning and to commonly accepted expressions in natural language that seem to imply ontological commitments to possible worlds. A common objection to modal realism is that it leads to an inflated ontology, which some think runs counter to Occam's razor. Critics of modal realism have also pointed out that it is counterintuitive to allow possible objects the same ontological status as actual objects. This line of thought has been further developed in the argument from morality by showing how an equal treatment of actual and non-actual persons would lead to highly implausible consequences for morality, culminating in the moral principle that every choice is equally permissible.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
Possible passages
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Vice and crime, on the other hand, arise there through the free inward operation of the creature, in so far as this can occur within the instant, repetition afterwards rendering it discernible. 389. This anteriority of nature is a commonplace in philosophy: thus one says that the decrees of God have an order among themselves. When one ascribes to God (and rightly so) understanding of the arguments and conclusions of…
Gottfried Wilhelm Leibniz, Theodicy Essays on the Goodness of God, the Freedom of Man and the Origin of Evil
States what Modal realism is; the author is tied to Modal realism in the knowledge graph.
(2) The _Realism_ of the purposiveness of nature is also either physical or hyperphysical. The _former_ bases the purposes in nature, by the analogy of a faculty acting with design, on the _life of matter_ (either its own or the life of an inner principle in it, a world-soul) and is called _Hylozoism_. The _latter_ derives them from the original ground of the universe, as from an intelligent Being (originally…
Immanuel Kant, Kant's Critique of Judgement
States what Modal realism is.
The postulate of the possibility of things requires also, that the conception of the things agree with the formal conditions of our experience in general. But this, that is to say, the objective form of experience, contains all the kinds of synthesis which are requisite for the cognition of objects. A conception which contains a synthesis must be regarded as empty and, without reference to an object, if its…
Immanuel Kant, The Critique of Pure Reason
States what Modal realism is.
Philosophers who discussed Modal realism
Related ideas
- Gottfried Wilhelm Leibniz
- Philosophy
- Subjunctive possibility
- Infinity
- Robert Merrihew Adams
- Metaphor
- Natural language
- Obligation
- Platonism
- Set (mathematics)
- Set theory
- Spacetime
- Utilitarianism
- Modal logic
- Willard Van Orman Quine
- Occam's razor
- Causality
- David Lewis (philosopher)
- Robert Stalnaker
- Morality
- Quantifier (logic)
- Reality
- Saul Kripke
- Reductionism
Opposing perspectives
Place in the tradition
Part of American philosophy.