Logical possibility

A logically possible proposition is one that can asserted with out entailing a contradiction.

Logical possibility should be distinguished from other sorts of subjunctive possibilities. For example, it may be logically possible for the universe's physical laws to be different from what they actually are. If it is, then many things which we would normally consider to be demonstrably impossible can be logically possible: for example, traveling faster-than-light might be possible or escaping from black holes is not impossible. Many philosophers, then, have held that these scenarios are logically possible but nomologically impossible (impossible under the actual laws of nature).

With this understanding of logical possibility in mind, other logical modalities may be defined in terms of it: a proposition is logically necessary if it is not logically possible for it to be false in some possible world, logically impossible if it is not logically possible for it to be true in some possible world, and logically contingent if it is logically possible for it to be true and logically possible for it to be false in some possible world. Logical possibility can be further distinguished from metaphysical possibility, as the former refers to what is permissible in a logically possible world (i.e. contains no contradictions), while the latter concerns how the world could have actually been. possible world. Given the aforementioned description of logical possibility, some propositions can be logically possible and yet metaphysically impossible (some philosophers take metaphysical possibility to be construed as distinct and narrower than logical possibility i.e Water is H2O, is metaphysically necessary while still logically contingent).

See also

• Modal logic
• Paradox
• Possibility theory
• Possible world
• Subjunctive possibility

External links

• Do Modal Claims Imply the Existence of Possible Worlds?, paper criticizing David Lewis' theory of possibility.