Implicature, Presupposition, and Speech Acts

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• Implicature, Presupposition, and Speech Acts

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A Goal for Question-Answering Systems

• Understanding queries
• S Are you traveling to La Guardia?
• U Im going to New York.
• U When does the 5 oclock train leave from
  Newark?
• S (thinks) U believes there is a 5 oclock train
  from Newark.
• S I heard you say New York City?
• U New York City./?

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• Cooperative responses
• Correcting misconceptions
• U When does the 5 oclock train leave from
  Newark?
• S (thinks) U believes there is a 5 oclock train
  from Newark.
• S There is no 5 oclock train from Newark there
  is a 520 tho.
• Providing more information than is asked for
• U Do I have the 500 minimum in that account?
• S1 Yes.
• S2 You have 739.

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Discourse Pragmatics

• Context-dependent meaning, invited inference,
  intended meaning vs. propositional content
• Speech Acts and illocutionary force
• Presupposition
• Implicature
• Conversational
• Conventional

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Speech Acts (Austin, Searle)

• Can you tell me the time? Can you open the
  window?
• Locutionary acts the act of uttering
• Illocutionary acts the act the utterance is
  intended to perform (question, assertion,
  exclamation)
• Perlocutionary acts the rhetorical act intended
  by S in performing the illocutionary act (getting
  H to do something, conveying to H that S is
  cold,)

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Linguistic Cues to Speech Act Identification

• Performative verbs
• Can indicate illocutionary force promise, order,
  ask, beseech, deny, apologize, curse
• But not perlocutionary force (I convince you to
  vote for me for president)
• Speech acts in NLP often identified with
  illocutionary force
• Cottage industry in identifying speech acts
  automatically from large labeled corpora using
  lexical and acoustic/prosodic cues

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Why Does It Matter?

• S/DA recognition important for
• Turn recognition (which grammar to use when)
• Turn disambiguation, e.g.
• S What city do you want to go to?
• U1 Boston. (reply)
• U2 Boston? (request for information)
• S Do you want to go to Boston?
• U1 Boston. (confirmation)
• U2 Boston? (question)

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• Same word/phrase -- different speech acts
• Okay acknowledgment, acceptance, question,
• Different word/phrase -- same speech act
• Yes, Right, Okay, Certainly,..
• Okay
• Contours distinguish different uses (Hockey 91)
• Contours context distinguish different uses
  (Kowtko 96)

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Using Prosodic Information for DA Identification

• Nöth et al 99 prosodic information improves DA
  identification
• Prosodic phrase boundaries signal potential DA
  boundaries
• Iding most frequently accented words in training
  corpus improves key-word selection for
  identifying DAs
• ACCEPT (ok, all right, marvelous, Friday, free)
• SUGGEST (Monday, Friday, Thursday, Wednesday,
  Saturday)

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Presupposition

• That which is taken for granted, given some
  linguistic expression X
• The King of France is bald.
• All of Hermans children are bright. (How many
  children does Herman have?)
• Test the negation and question presuppose the
  same thing
• The King of France is not bald. Is the King of
  France bald?
• None of Hermans children are bright. Are any of
  Hermans children bright?

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Linguistic Cues to Presupposition

• Factives
• Its a shame that X vs It is thought that X
• I realized that X vs I thought that X
• He managed to X vs He tried to X
• She regretted that X vs She feared that X
• ...
• Definites
• The X are Y (The King of France is bald vs. The
  King of France is dead)
• Lexical presupposition

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• John assasinated Bill (Bill died, the killing was
  intentional, the victim had some political
  status)
• Susan is accused of X (X is bad)
• Susan was criticized for X (X is bad and Susan
  did X)
• Merlin is a bachelor (Merlin is an unmarried male
  person)
• Presuppositions can be suspended but they cannot
  be felicitously denied
• All of Hermans children are bright, though he
  has no children.
• All of Hermans children are bright, if he indeed
  has children.

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Why do we care?

• Presuppositional information adds facts/beliefs
  to the database for NLP systems
• Information to store and check for accuracy
• My wife will also be a driver (S has a spouse)
• My number is 212-555-1212 (S has a telephone
  account)
• Ill take the red-eye (S believes there is a
  red-eye)
• Im upset about being charged for a call to
  Ethiopia (S was charged for a call to Ethiopia)
• Im a bachelor. (S is an unmarried male person)

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Conversational Implicature

• H. Paul Grice conversation is different from
  formal logic
• and is not , or is not v, some is not
• George got married and had a baby. Was it a boy
  or a girl? Some people sent baby gifts. Do
  they need clothes or toys? All the grandparents
  came to visit.
• Cooperative Conversation
• Make your conversational contribution such as is
  required, at the stage at which it occurs, by the
  accepted purpose or direction of the talk
  exchange in which you are engaged

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Maxims of Cooperative Conversation

• Maxim of Quantity
• 1. Make your contribution as informative as is
  required (for the current purposes of the
  exchange)
• 2. Do not make your contribution more than is
  required.
• Maxim of Quality
• Try to make your contribution one that is true.
• 1. Do not say what you believe to be false.
• 2. Do not say that for which you lack adequate
  evidence.
• Maxim of Relation Be relevant

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• Maxim of Manner Be perspicuous
• 1. Avoid obscurity of expression.
• 2. Avoid ambiguity.
• 3. Be brief (avoid unnecessary prolixity).
• 4. Be orderly.
• Maxims may be
• Observed
• John got into Columbia and won a scholarship.
• Violated quietly
• I never said that.
• Flouted
• He has excellent handwriting.

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• Speakers may not be able to observe all maxims
  simultaneously
• Implicature interpretation requires both S and H
  to be in sync
• That which S licenses and H infers via the CP and
  the Maxims
• A. I got an A on that exam.
• B. And Im Queen Marie of Rumania.
• A. Where did you go?
• B. Out.

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• A Where does Arnold live?
• B Somewhere in southern California.

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Other Implicatures

• Generalized Conversational, e.g. indefinites
• A car ran over Johns foot. (not Johns car)
• John broke a foot yesterday. (Johns foot)
• John broke a nose yesterday. (not his own)
• Conventional
• George is short but brave.
• George is short therefore he is brave.

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Distinguishing among Types of Meaning

• The King of France is bald but handsome.
• Propositional content
• What is asserted (entailed)
• Presupposition
• What is taken for granted, even if the
  propositional content is negated or questioned

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• What are you getting me for Christmas?
• The King of France is bald but handsome.
• Conversational implicature
• What is implicated
• Cancelable/defeasible
• Nondetachable
• Conventional Implicature
• What is implicated
• Not cancelable/defeasible
• Not nondetachable

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For Next Class

• Read Ch 4.7