Implicature and Explicature


Linguists and philosophers try to draw a line between semantics and pragmatics. Semantics is concerned with the literal meaning of words and sentences, while pragmatics analyzes the contributions of context to the final interpretation of sentences. The examples of conversational implicature introduced by Paul Grice provide good examples of the ways in which extra-linguistic factors impinge on our understanding of sentences. Grice’s conversational implicatures provide a good starting point for analyzing the contribution of context to semantic. In this section we explore the dependency of sentence interpretation on context.


Theories of implicature often take for granted that the literal meaning of sentences, or explicature, can be separated from the sentences’ implicatures. However, reference to the context of a sentence is almost always needed to construct its literal meaning. Contextual information is used for: i) the disambiguation of ambiguous expressions, ii) the assignment of reference to variables, and iii) the interpretation of indexical expressions.


Contextual information can be used to disambiguate both lexical and structural ambiguities, as in the following sentences.


41a. They’ve got that creamy duck on special at Weaver’s.

    b. Everyone should bring a pencil.


The assignment of reference to variables is needed to interpret pronouns and time reference. This is illustrated in the following sentences.


42a. He’ll never make it.

    b. I left your mail on your desk.

    c. The plumber came and he’ll send a quote.

    d. Everyone came to dinner last night and Jones got tipsy.


Indexical or deictic expressions derive their interpretation from the context. Indexical expressions express the central anchoring points of an utterance such as the identity and position of the participants, the time and place of the utterance.


Obviously, the evaluation of deictic expressions must be part of any sentence’s explicature. Assuming that explicature is responsible for determining the truth conditions for a sentence raises the question of whether we can maintain a clear boundary between explicature and implicature. Another possibility is that literal meaning constrains the ways in which listeners make use of implicature in determining truth conditions.



Pronouns


At one time linguists distinguished between “deictic” and “anaphoric” uses of person pronouns. Deictic pronouns receive their interpretations through the non-linguistic context as in the sentence


      I wonder who she is.


An anaphoric pronoun receives its reference from its linguistic context as in the following sentence.


      Jeb thinks he knows everything.


A long syntactic tradition attempts to connect pronoun interpretation to a set of binding conditions, but there are many examples of pronoun usage beyond the deictic pronouns that do not fit simple binding rules:


      Most accidents that Mary reported were caused by her cat.

      I don’t know Smith. Is he a linguist?


One question is whether a single theory for the interpretation of pronouns can account for all of these examples. People rely on many sources of information to make the correct pronoun interpretation. Jurafsky & Martin (2000) describe several of these sources.


Selectional restrictions


Many verbs limit the types of objects they can take. Pronouns that occur with such verbs probably refer to entities that meet the verb’s selectional restrictions. Consider the following sentences


      I found a bowl on the table.

      I filled it with candy.


Here the verb fill selects objects that can be used as containers. We are more likely to use a bowl than a table as a container, so the bowl is the most likely referent for the pronoun it.

      The only difficulty in using selectional restrictions to resolve pronoun reference comes through metaphorical contexts. Consider the following example


      Tom has a new sound card for his computer.

      It fills his need for material possessions.


Practically anything can be used to fill abstract needs and desires. The listener has to use their background knowledge of Tom and the context to compute the pronoun’s interpretation.


World knowledge


Many times hearers rely on their knowledge of the real world to resolve pronoun interpretation. Consider this example


      Tom bought a new sound card for the computer.

      It still needs several more upgrades.


Here, we are most likely to interpret the pronoun as referring to the computer rather than to the sound card, since computers are the sort of thing that is constantly in need of an upgrade. Computer upgrades are probably not part of the lexical meaning of the word computer, but rather come about through an interaction with computers in the real world.


Recency


Everything else being equal, we are more likely to tie pronoun reference to an object mentioned in the most recent sentence. See the following example


      Sally got a blue case for her computer.

      Mabel’s computer has a red case.

      I like it better.


In this example, there is a strong preference to interpret the pronoun it as referring to the case on Mabel’s computer rather than the case on Sally’s.


Grammatical Relation


Listeners display the following preference hierarchy for pronoun interpretation


      Subject > Object > Oblique


Consider the following example


      Tom went to the computer store with Ralph.

      He found a sound card for his computer.


There is a slight preference for Tom over Ralph as the referent for the pronoun he in the second sentence. This preference hierarchy can be overridden fairly easily though. Consider the following example


      Tom took Ralph to the computer store.

      He found a sound card for his computer.


In this example the action of taking someone somewhere implies that the person who was taken was the one in need of new equipment for the computer. There would not be a good reason to mention Ralph if Tom was the only person interested in sound cards.


Repeated Mention


Pronouns are more likely to refer to entities that are mentioned repeatedly in previous sentences. Consider the following example


      Mabel took Sally to the computer store to look at sound cards.

      She didn’t like the noise her current card was producing.

      The sales clerk showed her a card she could afford.


In this example, listeners prefer to give the pronouns the same referent (Sally) throughout the entire sequence. English lacks a formal distinction between pronouns that signals when the pronoun referent has changed, so the default interpretation is to maintain the same referent over a sequence of sentences.


Verb Semantics


Some verbs emphasize specific arguments over others and this can affect pronoun reference. Consider the following sentences


      Mabel promised to ask Sally. She didn’t understand directions.

      Mabel hesitated to ask Sally. She didn’t understand directions.


There is a strong preference for Mabel to serve as the referent of the pronoun in the first sentence while Sally is strongly preferred in the second sentence. The verb hesitate focuses attention on the object of the embedded clause while the verb promise emphasizes the action of its subject. Local effects such as verb semantics can override preferences due to recency or repeated mention.



Discourse Relevance


      Heim & Kratzer (1998:240) suggest that listeners assign pronoun readings to the most salient individual(s) in the discourse. The factors that we have just reviewed in addition to the context of utterance would affect the saliency of potential pronominal referents. H & K go on to suggest that pronouns in sentences with quantified NPs are non-referring pronouns in contrast to the examples we have discussed so far. Examples of such a non-referring pronoun would be:


      Every farmer beats his donkey.

      Every farmer who owns a donkey feeds it.


Such sentences were introduced into the linguistics literature by Geach (1962) who noticed that they posed a difficulty for “copy and replace” theories of pronominal interpretation. What happens when you replace the possessive pronoun with ‘every farmer’ in the first sentence?


H & K argue that in such cases, the pronoun does not single out a single individual and therefore cannot refer to the most salient individual in the discourse. H&K claim that such examples should be analyzed as bound variables since the interpretation of the pronoun is fixed by the quantified expression.


The problem of sloppy identity is illustrated in the following sentence


      (On Mary’s birthday), Sally went to her office. Jane didn’t.


These sentences have several interpretations:


referential: (On Mary1’s birthday), Sally went to her1 office. Jane didn’t (go to her1 office).

sloppy identity: (On Mary1’s birthday), Sally2 went to her2 office. Jane3 didn’t (go to her3 office).


H&K attribute the first reading to a referential pronoun and sloppy identity to a bound variable reading. In order to make the referential reading work, H&K add the condition that pronouns in the same set of sentences cannot have both referential and bound readings. This stipulation rules out the interpretation where Sally goes to Mary’s office and Jane goes to her own (Jane’s) office.



Ellipsis


Ellipsis, like pronouns, provides a perspective on the degree to which listeners depend on extra-linguistic information to interpret sentence meaning. Ellipsis refers to the missing semantic content in sentences. Ellipsis frequently occurs in discourse contexts:


      A: Did you get up early today?

      B: No.


B’s response can only be interpreted in the context of the preceding question. The natural interpretation is the full statement:


      I did not get up early.


Note that English uses a different form of negation in discourse (no) and sentence contexts (not). The discourse form of negation occurs outside of the clause. The phenomena of ellipsis clearly demonstrate the abilities of speakers and listeners to use context to construct meanings. A compositional theory of semantics has to incorporate different aspects of the speech context to infer the intended meanings.


Ellipsis displays the same type of bound pronominal reference that we have already seen within single sentences:


      A: Who did every husband visit?

      B: His mother.


Ellipsis can occur across conjuncts:


      Which of his pictures is Tom submitting, and which is Harry?


Ellipsis also generates the same sloppy identity readings as pronouns.


      John thinks he’s clever. Bill does think Bill is clever too. John’s wife however does not think John/Bill is cleaver.


Ellipsis presents the same type of semantic challenge as pronominal interpretation. Early accounts of ellipsis treat it as a syntactic phenomenon. Ellipsis is one of the basic tests of syntactic constituency:


      A: Who dislikes Mary?

      B: John.


However, ellipsis is licensed outside of syntactic structure:

 

      Topics:            John, Mary dislikes; and Sue does too.

      Wh-islands:    John hasn’t [traveled with Mary], but I know a woman [who has ___ ].


Even within a syntactic constituent, ellipsis can still raise morphological issues. One suggestion was to waive the identity of phi-features to allow ellipsis with an unspecified pronominal that could be bound by the local subject:


      A: You’re sitting on my chair.

      B: No, I’m not sitting on your/my chair.


Clearly, retaining the first-person features gives the wrong interpretation, but suppressing the first-person features for some unspecified pronominal element isn’t sufficiently restrictive. What is required is the replacement of first-person by second-person features.


Dalrymple et al. (1991) introduced a semantic account of ellipsis. Consider an example of conjunct ellipsis:


      John sneezed and Bill did too.


Dalrymple et al. suggest extracting the semantic predicate rather than the syntactic predicate, and using the semantic predicate (sneeze (x)) as the basis for reconstruction. The basic idea is that some identical property P holds of both John and Bill, and resolving the ellipsis requires determining the value of P. Kearns discusses this process as lamba abstraction in section 4.4.


The Dalrymple et al. account generates both strict and sloppy readings in conjoined predicates:


      John is thinking of taking his mother to see his sister, and so is Bill.

 

Strict:  John is thinking of taking John’s mother to see John’s sister, and Bill is thinking of taking John’s mother to see John’s sister.

 

Sloppy:     John is thinking of taking John’s mother to see John’s sister, and Bill is thinking of taking Bill’s mother to see Bill’s sister.


This result gives the semantic approach an advantage over syntactic approaches that invoke an ambiguity in the syntactic structure of the source for the ellipsis.


Both syntactic and semantic accounts run into trouble accounting for ellipsis in sentences with quantified expressions:


      Each journalist interviewed a friend of mine, and each student did too.


If the indefinite expression a friend of mine takes wide scope in the first clause, then it also has wide scope in the elliptical clause with respect to each student. The semantic approach based on predicate extraction cannot account for the scope restrictions on quantified expressions.


These examples show that neither syntactic or semantic approaches alone explain the connection between the surface structure constituting the antecedent and the ellipsis site. Ellipsis reinforces the impression that sentence structure and semantics are best studied within a discourse context.



Pragmatic Contributions to Explicature


Robyn Carston (1988) draws attention to a range of ways in which listeners draw upon the context for sentence interpretation. Kearns points to the ambiguity in the sentence


49. The park is some distance from my house.


A logician might consider this sentence to be literally true even when the house is located across the street from the park. Many people would interpret the sentence to mean that the house is a long distance away from the park, at least two or more city blocks. Can we attribute such a discrepancy to implicature? Kearns believes the long distance interpretation should be part of the sentence’s explicature. She thinks this reading does not depend on the interpretation of indexical expressions, although she does not provide an analysis for some.


Kearns offers the following sentences as further evidence that the content of explicature must include contextual information.


53a. We don’t have enough rice.

    b. The park is too far from the house.


The words enough and too must be evaluated in relation to some unexpressed purpose or proposed action. Such purposes can be overtly expressed as in the following sentences:


54a. We don’t have enough rice to make curry and rice for three people.

    b. The park is too far away from the house to walk the distance in half an hour.


Carston also investigates the variable interpretation of the sentence connective and. Kearns provides the following examples:


55a. Alice opened the wine and poured a glass.

    b. Alice opened the wine and after that poured a glass.


56a. Jackie has won the Golden Kiwi and she’s going to pay off the mortgage.

    b. Jackie has won the Golden Kiwi and as a consequence she’s going to pay off the mortgage.


57a. Stephen was tuning his bike and he was listening to the cricket.

    b. Stephen was tuning his bike and simultaneously he was listening to the cricket.


Listeners are aware of the different connections between these sentences even without the and:


59a. Alice opened the wine. She poured out a glass.

    b. Stephen was tuning his bike. He was listening to the cricket.


Carston argues that this pragmatic information should be part of the explicature. She uses evidence from responses to questions and assertions. The following response is made to the explicature, not the implicature:

 

60. (Jones is generally scruffy, but tidies himself up from time to time when he was a girlfriend. His friends are familiar with this pattern.)


      A: Jones has transformed himself again. (implicature: Jones has a new girl.)

      B: No he hasn’t. (Denying that he has clean up his act, not that he has a new girl.)


Unlike implicature, the pragmatic relation between clauses can be questioned or denied, e.g.,


      A: Jackie has won the Golden Kiwi and she’s going to pay off the mortgage.

      B: I thought she paid off the mortgage from her inheritance.

 

61. A: (to director) I light her cigarette and she smiles, right?

      B: No, she smiles and then you light her cigarette.


Carston also discusses examples like (64):


64. It’s better to meet the love of your life and get married than to get married and meet the love of your life.


These examples point to the need to include a wide variety of pragmatic information in interpreting literal meaning.


Grice maintained that implicatures are logically independent of what the speaker actually says. The explicature of the sentence The movie ends at 3:50 is independent of the implicature You can see the film and still attend your 4 o’clock lecture. We can cancel this implicature by adding But I was forgetting the detour at Fifth. We cannot cancel explicature in the same fashion. As Kearns states:

 

the literal meaning of a sentence lays down a framework which determines the set of propositions, perhaps infinitely many, that a speaker can express by uttering the sentence. But the context allows the hearer to identify which of these propositions the speaker actually expressed. (281)



Metaphor


One of the most frequent violations of Grices conversational principles occurs when we use

metaphor. Metaphors like ‘You’re the cream in my coffee’ obviously violate the Maxim of

Quality since they state propositions that are not literally true.


Lakoff and Johnson (Metaphors We Live By) observe that many metaphors observe common

themes, e.g.,

      Good is up


      Examples:

            I’m feeling up. That boosted my spirits. My spirits rose.

            You’re in high spirits. I’m feeling down. I’m depressed.


Much of our language about language is structured by metaphor:

      IDEAS (or meanings) are objects.

      linguistic expressions are containers.

      communication involves sending ideas in containers.


Examples:

      It’s hard to get that idea across to him.

      I gave you that idea.

      It’s difficult to put my ideas into words.

      His words carry little meaning.

      The sentence is without meaning.


What difficulties does metaphor create for a theory of meaning that uses truth conditions?



References

 

Cann, R., Kempson, R. and Purver, M. 2007. Context-dependent wellformedness: the dynamics of ellipsis. Research on Language and Computation 5.333-358.

Carston, R. 1988. Implicature, explicature and truth-theoretic semantics. In R. M. Kempson (ed.), Mental Representations: The Interface Between Language and Reality, 155-181. Cambridge: Cambridge University Press.

Dalrymple, M., Shieber, S. and Pereira, F. 1991. Ellipsis and higher-order unification. Linguistics and Philosophy 14.399-452.

Geach, P. 1962. Reference and Generality. Cornell University Press.

Heim, I. & Kratzer, A. 1998. Semantics in Generative Grammar. Malden, MA: Blackwell.

Jurafsky, D. & Martin, J. H. 2000. Speech and Language Processing. Upper Saddle River, NJ: Prentice Hall.

Lakoff, G. & Johnson, M. 1980. Metaphors We Live By. Chicago: University of Chicago Press.

Lappin, S. & Benmamoun, E. (eds.) 1999. Fragments: Studies in Ellipsis and Gapping. Oxford University Press.