Notes to Intensional Logic

1. Actually, in the original 1946 paper, Marcus is working in S2, and she uses the fishhook, fishhook, representing “necessary implication”, to formulate the Barcan formula, not material implication. It doesn’t make a difference in the more usual modal logics, but it is important to know how the original was formulated.

Copyright © 2015 by
Melvin Fitting

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