PHIL 2020 Lecture Notes - Lecture 2: Propositional Calculus, Law Of Excluded Middle
19 May 2017
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New vocabulary: our new language introduces three new concepts: predicates, quantifiers and constants, there are no more simple statement variables. Instead, the basic element of our language will be predicates. If they are not operated on, then every predicate will make a predication of a constant (or constants). Just like when we picked an abbreviation for simple statements, we want to pick a letter that makes clear what predicate we are translating. Socrates: mx = x is a mortal, hx = x is a (hu)man, the predicate is symbolized with an upper-case, latin letter. The subject of the predicate is indicated with a lower-case latin letter, which is recorded after the predicate. Constants: we treat the subjects of predications as constants. Constants and variables: since both constants and variables are abbreviated with lower-case latin letters, we need to set up a (cid:272)o(cid:374)(cid:448)e(cid:374)tio(cid:374) that assu(cid:396)e that (cid:449)e do(cid:374)(cid:859)t get the two mixed.
