Chapter 4 Presupposition and entailment

1、 Now we look at two kinds of inference. Entailment emphasizes the relationship between sentences that forms the basis for some other inferences. Presupposition emphasizes the inference that is more context-dependent. Presupposition and entailment are technical terms used to describe two different as

2、pects of the information that speakers assume that listeners already know. Presupposition is something the speaker assumes to be the case prior to making an utterance. Speakers, not sentences, have presuppositions. Entailment is something that logically follows from what is asserted in the utterance

3、. Sentences, not speakers, have entailments. PresuppositionIn the USA, an accused mugger rather foolishly chose to defend himself at the trial. The following is one of the questions he put to his victim. Did you get a good look at my face when I took your purse? Why do you think the accused mugger i

4、s so foolish?Presupposition Look at the relationship between the following two propositions. a. Marys dog is cut. (=p) b. Mary has a dog. (=q) c. p q (p presupposes q) a. Marys dog isnt cute. (=NOT p) b. Mary has a dog. (=q) c. NOT p q Presupposition a. Everybody knows that John is gay. (=p) b. Ever

5、ybody doesnt know that John is gay. (=NOT p) c. John is gay. (=q) d. p q & NOT p q Constancy under negation: The presupposition of a statement will remain constant (i.e. still true) even when that statement is negated. Types of presupposition triggerLexical Examples Existential s , the, that, th

6、is, these, those factiveRealize, regret, knowNon factive Dream, imagine, pretendStructural Examples“if” conditional structure If you were my friend, you would have helped me. You are not my friend. Wh-question /subordinate clause When did he leave? He left. Types of presupposition trigger Decide whi

7、ch ones contain the presupposition that at the time the utterance was made “ There was a chocolate cake”. What do those utterances have in common?1. (a) Mike might find the chocolate cake in the kitchen. (b) Mike might find a chocolate cake in the kitchen.2. (a) Is Mike giving Annie that chocolate c

8、ake? (b) Is Mike giving Annie a chocolate cake?3. (a) Did Mike hide a chocolate cake? (b) Did Mike hide Annies chocolate cake?Types of presupposition triggerShe didnt realize he was ill. ( He was ill.) I wasnt aware that she was married. ( She was married. ) I dreamed that I was rich. ( I was not ri

9、ch.) If you were my friend, you would have helped me. ( You are not my friend. )Types of presupposition triggerDecide which ones contain the presupposition that “Mike smashed the television”. What do those utterances have in common?a. Did Mike smash the television?b. When did Mike smash the televisi

10、on?c. I was eating popcorn when Mike smashed the television. d. Why did Mike smash the television?e. I dont understand why Mike smashed the television.f. I wonder if Mike smashed the television.g. I wonder how Mike smashed the television. The projection problem see pp30-31 12 14 The meaning of some

11、presuppositions (as parts) doesnt survive (project) to become the meaning of some complex sentences (as wholes). How to explain the projection problem? It is destroyed by entailment. The entailment (a necessary/logical consequence of what is said) is simply more powerful than the presupposition (an

12、earlier assumption). The projection problem The power of entailment can also be used to cancel existential presupposition. a. The King of England visited us. ( the existence of king) b. The King of England doesnt exist! (-There is not a king.) The presupposition of “the existence of king” is cancell

13、ed by the entailment of b. Summary We have described presuppositions as inferences about what is assumed in an utterance rather than directly asserted. Presuppositions are closely linked to the words and grammatical structures that are actually used in the utterance and our knowledge about the way l

14、anguage users conventionally interpret them. Presuppositions can be cancelled by entailment. Entailment Suppose that sentence (a) in each pair is true. Then look at sentence (b) and decide if you can assume that it is automatically true. 1. (a) Annie caught a trout. (b) Annie caught a fish. 2. (a) A

15、nnie is thin. (b) Annie is not fat. 3. (a) Annie baked a cake. (b) Annie baked something. Entailment Once sentence (a) is true, sentence (b) becomes automatically true. Sentence(b) is an entailment of sentence (a).This kind of inference is “for free”. It requires only a knowledge of the semantics. T

16、rout/fish, thin/fat, cake/something. Ordered entailments One utterance may involve very large number of background entailments. The speaker will indicate how these entailments are to be ordered. The speaker will communicate by stress, which entailment is assumed to be in the foreground. a. Rover cha

17、sed THREE squirrels. (three is foregrounded.) b. ROVER chased three aquirrels. (ROVER is foregrounded.)Ordered entailments Using “it-cleft” construction This is particularly useful in written language where stress is not available. a. The PAINTERS broke the window. (spoken) b. It was the painters wh

18、o broke the window. (written) When the cleft construction is used in spoken language combined with heavy stress, some interesting meaning differences can emerge. Compare: a. It wasnt ME who burnt the toast. (it is anybody else) b. It WANSNT me who burnt the toast. (It was me)Summary All sentences ha

19、ve a number of entailments-other sentences which are automatically true if the original sentence is true. Entailments are inferences that can be drawn solely from our knowledge abut the semantic relationship in a language. This knowledge allows us to communicate much more than we actually “say”. Exe

20、rcises Here are three different stress patterns for Annie ruined the sweater. Try to tell which entailment is being foregrounded. a. Annie RUINED the sweater. b. Annie ruined the SWEATER. c. ANNIE ruined the sweater. Exercises Which of the following sentences cannot be designated as “true” or “false” unless you have extra non-linguistic information? a. My hamster is a mammal. b. My cousin is a girl. c. My sister is a gir