LIN241H1 Lecture Notes - Lecture 8: Propositional Attitude, Hersham And Walton Motors, Gottlob Frege
Document Summary
If we identified the meaning of a sentence with its truth-value, we wouldn"t be able to account for the fact that sentences with the same truth-value can have different meanings. The meaning of a sentence is not its extension but the intension. Intension of a sentence is a proposition: to define a proposition, must use the concept of possible-worlds. [[john smokes]]m,c,g,w = 1 iff john smokes in w. In our world: v(dodo)(w) = v(pterosaur)(w) = , there is some possible world w" such that, v(dodo)(w") v(pterosaur)(w", thus, dodo and pterosaurs have different intensions, although they have the same extension in our world. [[john smokes]]m,c,g,w = 1 iff [[john]]m,c,g,w [[smokes]]m,c,g,w. More interestingly, we can now define propositions as sets of worlds. The intension of a sentence s is simply: Easy to confuse between truth-values and propositions. {w: [[john smokes]]m,c,g,w = 1} is a proposition: certain expressions of english take propositions are arguments, rather than truth-values.
