句子语义学词和词之间有各种各样的意义关系，我们称之为sense relation。
句子也一样，可以有各种意义关系。
句子语义学是在句子层面对意义进行研究，并把句子当成一个整体来看待。
◆Presupposition前提/预设，这一概念是由哲学家弗雷格（G.Frege）首先提出来的。
在言语交际中，我们所说的一句句话并不是孤立的，相互之间毫无联系的。
相反前一句话和后一句话往往有密切的联系。
Please open the door.这句话的意思很清楚，就是“请把们打开”，但是说这句话必须有一个前提，那就是“现在要开的门再说话时是关着的”。
所以从语义的角度来看，句子所包含的“前提”和这个句子本身的意义有十份密切的关系句子的前提有这样的特点：否定了句子本身，句子的前提保留不变。
John is married.John exists.John is not married.◆Semantic presupposition and pragmatic presupposition语义预设是对语句之间关系所做的逻辑分析，他面对的是一种不变的关系：即如果P在语义上预设Q, 则P总是在语义上预设Q。
但在实际的语言活动中（语用预设），预设通常不是语义中稳定的不受约束的部分。
这也正是有些语言学家认为预设属于语用学而不属于语义学的主要原因。
一个重要的事实是，在一定的语境里，预设会消失，也就是说预设具有可消失性(defeasibility)。
例如：Sue cried before she finished her thesis.Sue died before she finished her thesis.◆What is Semantic Presupposition?In many discussions of the concept, presupposition is treated as a relationship between two propositions by the linguists. If we say the sentence in (1a.) contains the proposition p and the sentence in (1b.) contains the proposition q, then, using＞＞to mean …presupposes‟, we can represent the relationship as in (1c.).(1) a. Mary‟s dog is cute. (＝p)b. Mary has a dog. (= q)c. p ＞＞qInterestingly, when we produce the opposite of the sentence in (1a.) by negating it (= NOT p), as in (2a.), we find that the relationship of presupposition does not change. That is, the same proposition q, repeated as (2b.), continues to be presupposedby NOT p, as shown in (2c.).(2) a. Mary‟s dog isn‟t cute. (＝NOT p)b. Mary has a dog. (= q)c. NOT p ＞＞qPresupposition is an inference（推论）to the proposition of the sentence. Take the following sentences for example again:e.g. (3) John is married.(4) John exists.(5) John is not married.Comment: if (3) is true, (4) is true; if (3) is not true, (4) is still true. In this case, we can say both (3) and (5) presuppose (4). A presupposition is something the speaker assumes to be the case prior to making an utterance. Speakers, not sentences, have presuppositions. An entailment is something that logically follows from what is asserted in the utterance. Sentences, not speakers, have entailments.◆Semantic presupposition would be based on the following definition:Sentence A semantically presupposes another sentence B iff:if and only if, iff是充分必要条件(a) in all situations where A is true, B is true(b) in all situations where A is false, B is true◆Types of presuppositionPotential presupposition: in the analysis of how speakers‟ assumptions are typically expressed, presupposition has been associated with the use of a large number of words, phrases, and structures. These linguistic forms shall be considered as indicators of potential presuppositions, which can only become actual presuppositions in contexts with speakers. The following kinds of presuppositions are all potential presuppositions. Now we‟ll look at the major presupposition types marked by different linguistic features.◆Existential presupposition: presuppose the existence of something.(my). It is not only assumed to be present in possessive constructions, but more generally in any definite descriptions such as definite noun phrase with determines …the‟, …this‟, …that‟, …these‟, …those‟, etc. By using any of the expressions in (16), the speaker is assumed to be committed to the existence of the entities named.(16) e.g. The king of Sweden, the cat, the girl next door (Yule, 2004: 27)◆Factive presupposition: presuppose something as a fact.(know). A number of factive verbs, such as …realize‟in (17a) and …regret‟in (17b), as well as phrases involving …be‟ with …aware‟ in (17c), …odd‟ in (17d), and …glad‟ in (17e) have factive presuppositions.(17) a. She didn‟t realize he was ill.(＞＞He was ill)b. We regret telling him.(＞＞We told him)c. I wasn‟t aware that she was married.(＞＞She was married)d. It isn‟t odd that he left early.(＞＞He left early)e. I‟m glad that it‟s over.(＞＞It‟s over)The presupposed information following the verb …know‟ can be treated as a fac t, and is described as a factive presupposition. Words like know, realize, regret as well as phrases involving …be‟ with …aware‟, …odd‟, and …glad‟ have factive presuppositions. (Yule, 2004: 27-28)◆Lexical presupposition: when a specific word triggers a presupposition. It is featured by implicative verbs like …manage‟, …start‟, …stop‟, …forget‟, etc. Generally speaking, in lexical presupposition, the use of one form with its asserted meaning is conventionally interpreted with the presupposition that another (non-asserted) meaning is understood.Each time you say that someone …managed‟to do something, the asserted meaning is that the person succeeded in some way. When you say that someone …didn‟t manage‟, the asserted meaning is that the person did not succeed. In both cases, however, there is a presupposition (non-asserted) that the person …tried‟to do that something. So, …managed‟ is conventionally interpreted as asserting …succeeded‟ and presupposing …tried‟.(18) a. He stopped smoking.(＞＞He used to smoke)b. They started complaining.(＞＞They weren‟t complaining before)c. You‟re late again.(＞＞You were late before)Lexical presupposition: in lexical presupposition, the use of one form with its asserted meaning is conventionally interpreted with the presupposition that another(non-asserted) meaning is understood. For example, someone …managed‟ to do something, the asserted meaning is that the person succeeded in some way. Someone …didn‟t manage‟; the asserted meaning is that the person did not succeed. In both cases, there is a presupposition (non-asserted) that the person …tried‟ to do that something. So …managed‟is conventionally interpreted as asserting …succeeded‟ and presupposing …tried‟. Other examples, involving the lexical items, are …stop‟, …start‟, and …again‟. (Yule, 2004: 28)◆Structural presupposition: certain sentence structures presuppose something to be true.(wh-questions). We might say that speakers can use such structures to treat information as presupposed (i.e. assumed to be true) and hence to be accepted as true by the listener.For example, the wh-question construction in English, as shown in (19a) and (19b), is conventionally interpreted with the presupposition that the information after the wh-form is already known to be the case.a. When did he leave?(＞＞He left)b. Where did you buy the bike?(＞＞You bought the bike)Certain sentence structures have been analyzed as conventionally and regularly presupposing that part of the structure is already assumed to be true. We might say that speakers can use such structures to treat information as presupposed (i.e. assumed to be true) and hence to be accepted as true by listener. For example, the wh-question construction in English is conventionally interpreted as that the information after the wh-form is already known to be the case. Such structurally-based presuppositions may represent subtle ways of making information that the speaker believes appear to be what the listener should believe.(wh-questions)◆Non-factive presupposition: It is one that is assumed not to be true. Verbs like …dream‟, …imagine‟, and …pretend‟, as shown in (20), are used with the presupposition that what follows is not true.(20). a. I dreamed that I was rich.(＞＞I was not rich)b. We imagined we were in New York.(＞＞we were not in New York)He pretends to be ill.(＞＞He is not ill)◆Counter-factural presupposition: What is presupposed is not only not true, but is the opposite of what is true, or …contrary to facts‟. (Conditional structure)A conditional structure of the type shown in (21), generally called a counterfactual conditional, presupposes that the information in the if-clause is not true at the time of utterance.(21). If you were my friend, you would have helped me.(＞＞you are not my friend)Summary:◆The properties of presuppositions★Cancel ability / Defeasibility:Levinson(1983:186) states that they can be cancelled out by either the immediate linguistic context or by some wider context or mode of discourse. If we say …The committee failed to reach a decision‟, it presupposes that they tried, but we can cancel out that presupposition if we add …because they didn‟t even get round to discussing it‟. Similarly, we can argue presupposition out of the way by a variant on the reductio ad absurdum (the disproof of a proposition by showing that its conclusion can only be absurd) mode of discourse: …He didn‟t do it, and she didn‟t do it…In fact, nobody did it ‟. They are defensible in (a) certain discourse contexts, (b) certain intra-sentential context. This property will prove to be the undoing(doing away with) of any possible semantic theory of presupposition. They are defeasible in certain intra-sentential contexts and certain discourse context, for example,(1) Sue cried before she finished her thesis.(2) Sue finished her thesis.(3)Sue died before she finished her thesis.In Sentence(3) the presupposition seems to drop out, since we generally hold that people do not do things after they die, it follows that she could not have finished her thesis. They are liable to evaporate in certain contexts, either immediate linguistic context or the less immediate discourse context, or on circumstances where contrary assumptions are made.(Levinson,2001, p187)Another kind of contextual defeasibility arises in certain kinds of discourse contexts. For example, the cleft sentence 1 is supposed to presuppose 2:1. It isn‟t Luke who will betray you.2. Someone will betray you.You say that someon e in this room will betray you. Well maybe so. But it won‟t be Luke who will betray you, it won‟t be Paul, it won‟t be Matthew, and it certainly won‟t be John. Therefore no one in this room is actually going to betray youHere each of the cleft sentence(It won‟t be Luke, etc.)should presuppose that there will be someone who will betray the addressee. But the whole purpose of the utterance 1 is, of course, to persuade the addressee that no one will betray him, as stated in the conclusion. So the presupposition is again defeated; it was adopted as a counterfactual assumption to argue to the untenability (站不住脚) of such an assumption.So far we have shown that some of the core examples of presuppositional phenomena are subject to presupposition cancellation in certain kinds of context, namely:(i)Where it is common knowledge that the presupposition is false, the speaker is not assumed to be committedto the truth of the presupposition(ii) Where what is said, taken together with background assumptions, is inconsistent with what is presupposed, the presuppositions are cancelled, and are not assumed to be held by the speaker(iii) In certain kinds of discourse contexts, presuppositions can systematically fail to survive.3.4.2 Presuppositions are apparently tied to particular aspects of surface structure. This property may serve to distinguish presupposition from conversational implicatures (which are tied to the context rather than the surface structure.), the other major form of pragmatic inference.( Levinson, S. C. 2001)There are no doubt many other kinds of contextual defeasibility as well, but these examples are sufficient to establish that presuppositions are defeasible by virtue of contrary beliefs held in a context. There are also many kinds of intra-sentential cancellation of suspension of presuppositions.(Levinson, 190)3.4.3 Projection in presupposition There is a basic expectation that the presupposition of a simple sentence will continue to be true when that simple sentence becomes part of a more complex sentence. This is one version of the general idea that the meaning of the whole sentence is a combination of the meaning of its parts. However, the meaning of some presuppositions (as …parts‟) does not survive to become the meaning of some complex sentences (as …wholes‟). This is known as the projection problem. (Yule, 2004: P30-33) Another explanation given by Levinson (Levinson, 1983: 191) is that Frege held that meanings of sentences are compositional, i.e. that the meaning of the whole expression is a function of the meaning of the parts. It was originally suggested by Langendoen & Savin (1971) that this was true of presuppositions too, and moreover that the set of presupposition of the complex whole is the simple sum of the presuppositions of the parts, i.e. if S0 is a complex sentence containing sentences S1, S2…S n as constituents, then the presuppositions of S0 = the presuppositions of S1 + the presuppositions of S2 …+ the presuppositions of S n .But such a simple solution to the presuppositions of complex sentences is far from correct, and it has proved in fact extremely difficult to formulate a theory that will predict correctly which presuppositions of component clauses will in fact be inherited/maintained by the complex whole. This compositional problem is known as the projection problem for presuppositions, and the particular behaviour of presuppositions in complex sentences turns out to be the really distinctive characteristic of presuppositions. (The Chinese version may be a little easier to understand:详见索振羽,《语用学教程》2000.北京大学出版社P136-140)◆Presupposition triggers: Some of the kinds of words and structures that seem to trigger presuppositions. Definite noun phrase/definite descriptions: words like the, this, that, these, those and possessives like my, Mary’s, your, prepositional phrase like with(two heads), in, etc. trigger the basic kind of presupposition. The possessives lead to a particularly strong presupposition about the existence of something; this is sometimes called existential presupposition. (Peccei, p20)John saw/didn‟t see the man with two heads.》there exists a man with two headsWH-words like when, why, how, etc. used either to ask questions or to introduce a subordinate clause to trigger the presupposition that the speaker has assumed “the person in question did something” is true. (Peccei, p 21)Mr. Givens, why is it important for people to understand body language---that is, communication by means of movements and gestures?Where do we get mannerisms such as these?Verbs that can trigger presuppositions: implicative verbs, factive verbs, change of state verbs and verbs of judging.1) Implicative verbs（含蓄动词）: manage, forget, happen, avoid etc. triggers the presupposition that some actions were conducted(manage), not expected(happen), or should have been conducted(forget).John managed/didn‟t manage to open the door》John tried to open the doorJohn forg ot /didn‟t forget to lock the door》John ought to have locked, or intended to lock, the doorsome further implicative predicates: X happened to V 》X didn‟t plan or intend to V; X avoid Ving 》X was expected to, or usually did, or ought to V2) factive verbs(述实动词/事实动词a verb followed by a clause which the speaker or writer considers to expressa fact:know, realize, regret, deplore（谴责）, I am aware, it is strange, it is odd that, be sorry that, be proud that, be indifferent that, be glad that, be sad that, etc. triggers the presupposition that what follows is a fact。
