Summary Of David Lewis On The Plurality Of Worlds

In his book On the Plurality of Worlds, David Lewis introduces his counterpart theory. This theory is first and foremost an argument from defence. Lewis presents this as a solution to the worries of possible world theory – namely the claims that possible worlds are concrete objects “entering into spatiotemporal relations with each other and nothing else” . This means that concrete possible worlds are real but are spatiotemporally closed from other worlds. This classification is an important factor for modal logic, as it means possible worlds are not taken to be ‘quasi-worlds’ but can stand on their own merit. This, however, leads to a major problem for the identity of a person, specifically that one cannot be a transworld individual. This means

Simply put, the indiscernibility of identicals states that if two objects have the same properties, then they must be the same thing. This, however, is not true, for example there may be a drinkable substance that is clear, boils at 100 centigrade and has a balanced ph. Level. This does not mean it is water, as it may have in a possible world, a different chemical makeup. Saul Kripke states that proper names such as water, or ‘Alex Imbert’ are rigid designators, that is they refer to the same thing in any possible world. If say, one were to change the chemical makeup of water, then for Kripke that substance in question would no longer be water. This view is transferable to an individual as well. Take myself, if I were to be different in a possible world, lets say I lost an arm, then that person would not be me, as actual ‘Alex Imbert’ is rigid to me and me alone. Even if the person in the possible world shares the same name as me, still, we would not be identical. It is important to note that even if the ‘Alex Imbert’ in the closest possible world to the actual world, who is exactly the same as me,