Full Idea
For the counterpart theorist, the trick is to say that 'Humphrey' names not the Humphrey of our world, and not the Humphrey of another, but rather the trans-world individual who is the mereological sum of all those local Humphreys.
Gist of Idea
In counterpart theory 'Humphrey' doesn't name one being, but a mereological sum of many beings
Source
David Lewis (On the Plurality of Worlds [1986], 4.1)
Book Reference
Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.197
A Reaction
On Lewis's perdurantism Humphrey is a 'spacetime worm' across his lifetime. Now we are adding all the possible Humphreys to the sum. I'm losing track of Humphrey's shape.