Lexicon of Arguments

 

IV 49
Counterpart/Lewis: There is no possible world in which I could have beem a basilisk - counterparts have to resemble the originals in important respects - the counterpart relation is never identity. >Counterpart theory/Lewis.

IV 29
Counterpart/Modal logic/Lewis: the theory of the counterpart (c.th.) and the modal logic with quantification (qML) are mutually translatable.
The c.th. has at least three advantages over qML:
1. it has no special intensive logic
2. it is not so obscure (opaque?)
a) uncertainty about analyticity and consequently
b) Uncertainty as to which descriptions describe possible worlds. (Which worlds are impossible).
c) which things are counterparts of what?
3. if our translation scheme is correct, then each sentence in qML has the same meaning as the corresponding sentence in c.th..
But not the other way around! Not every sentence of the c.th. is the translation or is equivalent to any sentence of the qML.
((s) Asymmetry: so the c.th. contains the qML and additional phrases that cannot be translated. So the c.th. is richer).

IV 35
Essence/counterpart/Lewis: Essence and counterpart can be defined mutually.
Essence: the essence of something is the attribute that shares something with all and only its counterpart.
Def Counterpart/Lewis: Counterpart of something is everything that has the essential attribute of it.
That doesn't mean that the attribute is the essence of the counterpart! It doesn't even have to be an essential attribute of the counterpart. ((s) Essence is not transitive over worlds).
. >Counterpart theory/Plantinga.