Lexicon of Arguments

 

I 128
"True in the other possible world"/Operator/Cresswell: ambiguous: ((lx)Oφx: "is such an x that x φ is in the other world".
Then: ((λx)Oφx)(s): the thing x (in this world, actual world) has the complex property of being wooden in the other possible world).
Ambiguous:
a) it is true in the other world that it is true in the other world that the largest wooden building is wooden. This can simply be represented like this: O(O(φs)).
b) if the parentheses are omitted: OOφs: then it is equivalent to φs.
This is appropriate for (18)

(18) It is true in the other possible world that the largest wooden building of the southern hemisphere is wooden in the other world

and certainly also for all specific descriptions.
Problem: then all the laws of classical logic do not longer apply.
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II 72
Def true/truth/Possible World Semantics/Cresswell: a sentence is true in a possible world iff this world is in the sets of worlds that is its intension (of the sentence).
>Possible world semantics.
((s): inversion of the definition of extension: extension of the sentence: set of worlds in which it is true).
>Truth values/Frege.
Cresswell: therefore one can say that the extension of the sentence is its truth value. (Frege).