laureano luna laureanoluna at yahoo.es
Wed Oct 19 14:42:02 EDT 2005

This post just means to ask for help.
I propose the following (usual) definitions:
1. A truth is contingent whenever its negation has a model.
2. For any sentence "p" and any model "M", M satisfies not-p whenever it does not satisfy p.
Add to these definitions the classical excluded middle for formal logic:  every sentence (closed well-formed formula) is either true or false.
Henkin´s semantics shows there are general non-standard models in which some sentences, that under classical excluded middle are second order logical truths, are not satisfied (since those models make SOL semantically complete, which it can´t be under classical excluded middle). 
According to 2. those models satisfy the negations of some second order logical truths.
According to 1. those logical truths (whose negations have a model) are contingent.
So, there must be some contingent second order logical truths.
What is wrong above?
Laureano Luna Cabañero.


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