The concept of possible worlds is useful because it defines the four modalities - possibility
necessity contingency and impossibility - but a challenge lies in defining it. David Lewis'
polemical hypothesis (genuine modal realism as it is called) succeeds in it. Lewis' modal
realism stirred controversy because he maintains that a plurality of worlds exists. Some
philosophers suggest that the Lewisian view is a violation to the law of parsimony also known
as Ockham's Razor i.e. not multiply entities beyond necessity. While avoiding a circular
definition Lewis constructs an inflated ontology. Is it worth it and if we do not want to
assume too many Lewisian worlds what alternatives remain? Actualist modal realism and modal
antirealism are the most relevant alternatives because modal abstentionism simply will not
progress in this direction. This study evaluates the theories of possible worlds.
