Summary Of David Lewis On The Plurality Of Worlds

In his book On the Plurality of Worlds, David Lewis introduces his counterpart theory. Lewis presents this as a solution to the concerns of possible world theory – namely the claims that possible worlds exist as concrete objects, “entering into spatiotemporal relations with each other and nothing else” – consequently making concrete possible worlds exist. However, one possible world cannot interact or affect another possible world, making them ‘spatiotemporally closed off’. This description is an essential factor for modal logic, as it conveys that they are complete existing worlds, rather than being ‘quasi-worlds’. Conversely, this leads to a major problem for the identity of a person, specifically that one cannot be a transworld individual. My …show more content…
Counterpart theory is the claim that a weak relation connects an object in the actual world to an object that exists in a possible world. Lewis calls this the counterpart relation, explaining that “you are in the actual world and not other, but you have counterparts in other worlds. Your counterparts resemble you closely in content and context in important respects. They resemble you more closely than do the other things in their worlds. But they are not really you. For each of them is in his own world, and only you are here in the actual world.” Lewis believes that counterparts resolve the problem of transworld identities. Counterpart theory can easily explain away how an individual can ‘seem’ to be in both the actual world and another possible world without needing to rely on breaking spatiotemporal boundaries. Using Lewis’ theory, one would formulate the sentence ‘if I took the bus, I would have been late for my appointment’ as ‘if my counterpart in a possible world had taken the bus, my counterpart would have been late for the appointment’. Using this formula, possible world theory once again becomes useful in talking about