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Philosophy

The Logic of Modal Realism and Concrete Possible Worlds

Quick fact

Lewis's theory is often called 'modal realism' because it treats the modal operators 'necesarily' and 'possibly' as quantifiers over a vast plurality of concrete worlds. He famously compared our position to being in a universe that is one of many, much like a grain of sand on a beach—yet each world is fully real.

Why this is interesting

If there are infinitely many universes just as real as ours, then every way the world could have been is actually a way some world is. What would that mean for your choices and your reality?