Possible worlds

Logic

Possible worlds are one of the foundational concepts in modal and intensional logics. Formulas in these logics are used to represent statements about what might be true, what should be true, what one believes to be true and so forth. To give these statements a formal interpretation, logicians use structures containing possible worlds. For instance, in the relational semantics for classical propositional modal logic, the formula ${\displaystyle \Diamond P}$ (read as "possibly P") is actually true if and only if ${\displaystyle P}$ is true in some world which is accessible from the actual world.