and six fingers at that world. But how should these modifiers be understood? According to McDaniel (2004), if Lewis is right, the defender of overlapping individuals has to accept genuine contradictions or defend the view that every object has all its properties essentially. How can you be one year older than you are? One way is to say that there is a possible world where you exist. Another way is for you to have a counterpart in that possible world, who has the property of being one year older than you. Trans-world individuals Take Humphrey: if he is a trans-world individual he is the mereological sum of all of the possible Humphreys in the different worlds. He is like a road that goes through different regions. There are parts that overlap, but we can also say that there is a northern part that is connected to the southern part and that the road is the mereological sum of these parts. The same thing with Humphrey. One part of him is in one world, another part in another world. "It is possible for something to exist if it is possible for the whole to exist. That is, if there is a world at which the whole of it exists. That is, if there is a world such that quantifying only over parts of that world, the whole of it exists. That is, if the whole of it is among the parts of some world. That is, if it is part of some world – and hence not a trans-world individual. Parts of worlds are possible individuals; trans-world individuals are therefore impossible individuals." Haecceity A haecceity or individual essence is a property that only a single object instantiates. Ordinary properties, if one accepts the existence of universals, can be exemplified by more than one object at a time. Another way to explain a haecceity is to distinguish between suchness and thisness, where thisness has a more demonstrative character. David Lewis gives the following definition of a haecceitistic difference: “two worlds differ in what they represent de re concerning some individual, but do not differ qualitatively in any way.” (Lewis 1986:221.) CT does not require distinct worlds for distinct possibilities – “a single world may provide many possibilities, since many possible individuals inhabit it” (Lewis 1986:230). CT can satisfy multiple counterparts in one possible world. Temporal parts Perdurantism is the view that material