1、1,Chapter FiveMeaning,2,1. The Study of Meaning,Semantics: The meaning of words: Lexical semantics The meaning of sentences: Propositional meaning, compositional meaning Linguistic semantics vs. Logical semantics/philosophical semantics,3,2. Semantic Meaning,Semantics is the study of meaning in lang

2、uage. Meaning has been studied for thousands of years by philosophers, logicians and then linguists. E.g. Laozi (China) Plato (2) writes red red eyes: white of eyes is red blue eyes: iris is blue,73,9. Propositional Logic,Truth condition: conditions which must hold for the sentence to be used to mak

3、e a true statement (at least if it is used literally). Thus, before we can truthfully say, on some occasion, The cat is on the mat, there must be some relevant feline occupying a specific position relative to an appropriate item of floor covering.,74,Those aspects of the meaning of a sentence which

4、determine its truth conditions are collectively known as the propositional content of the sentence. Two sentences with identical propositional content will yield statements with the same truth values on all occasions of use, as for instance, John caressed Mary and Mary was caressed by John. By the s

5、ame token, if two sentences have different propositional content, there will necessarily exist some conceivable situation in which they will yield statements with opposite truth values.,75,Proposition: a statement, with a truth value (true or false), eg The earth is flat. The earth goes around the s

6、un. All teachers are female.,76,9.1 Logical relations,Not/: P (false) And : PQ Or : PQ, PQ If then : PQ Equals to /(bi-conditional) : P Q,77,Truth value: Not ,78,Truth value: And ,79,Truth value: Or : PQ,80,Truth value: Or : PQ,81,Truth value: Ifthen ,82,Truth value: Equals to ,83,9.2 Predicate Logi

7、c,Argument and Predicate John runs. runs (John) or R(j) John loves Mary. loves (John, Mary) or L(j, m) John gave Mary a book. gave (John, Mary, book) or G(j, m, b),84,One-place predicate: run Two-place predicate: love Three-place predicate: give,85,Quantifiers: all , some All teachers are female. x (T(x) F(x) = For all x, if x is a teacher, x is female. Some teachers are female. x (T(x)F(x) = There are some xs that are b