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Drawing Conclusions. Entailment and Implicature. (1) Tom is an undergraduate. (2) Tom is a student. (3) I have a Siamese kitten. (4) I have a cat. Entailment. A relationship between two words or sentences such that if the first is true, the second must be true. Entailment Diagnostic.
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Drawing Conclusions Entailment and Implicature
(1) Tom is an undergraduate. (2) Tom is a student. (3) I have a Siamese kitten. (4) I have a cat.
Entailment • A relationship between two words or sentences such that if the first is true, the second must be true.
Entailment Diagnostic • A sentence X entails a sentence Y if whenever X is true, Y must be true as well • A sentence X entails a sentence Y if there is no situation in which X is true and Y is false.
Entailment constitutes a commitment on the part of the speaker. • Entailment allows the listener to make completely sure conclusions.
(1) Tom is an undergraduate. (2) Tom is a student. (3) I have a Siamese kitten. (4) I have a cat.
Entailment relationship not generally reciprocal (1) Tom is a student. (2) Tom is an undergraduate. (3) I have a cat. (4) I have a Siamese kitten.
(1) It’s hot outside. (2) It’s sunny. (3) The ground is wet. (4) It rained recently.
(1) It’s hot outside. (2) It’s sunny. (3) The ground is wet. (4) It rained recently. These conclusions may be reasonable, but the first statement of the pair does not entail the second.
Entailment Diagnostic • A sentence X entails a sentence Y if whenever X is true, Y must be true as well • A sentence X entails a sentence Y if there is no situation in which X is true and Y is false.
Applying the diagnostic X: The lawn is wet. Y: It rained recently. Is there ever a situation in which X is true and Y is not?
Applying the diagnostic X: The lawn is wet. Y: It rained recently. • rain • snow • dew • bucket of water/ice dumped • sprinkler system/lawn watering • washing car/sidewalk • guy peeing on it • people spitting on it …
Do people make conclusions not based on entailments? • Would anyone ever conclude that it had rained if someone commented that the ground was wet? • Of course!
Implicature • A conclusion drawn in conversation that is based on warranted evidence though not necessarily logically valid.
(1) I only slept four hours last night. (2) I am tired.
(1) There’s a funny smell in Evans Laboratory. (2) A chemistry experiment must have gone wrong.
(1) I was ironing this morning and I burned my finger. (2) I burned my finger while ironing.
People use contextual knowledge in making conclusions based on implicature • knowledge of the way the world is • Gricean maxims (rules of conversation)
Entailment or Implicature? X: If you give me a quarter, I’ll give you a cookie. Y: If you don’t give me a quarter, I won’t give you a cookie.
People are generally poor judges of entailment/implicature distinction. • Exploited by lawyers and advertisers, among others.
Scenario: An interrogation in a police station X: If you don’t tell us who gave you the gun, you’re going to prison for life. Y: If you tell us who gave you the gun, you will not go to prison for life.
Scenario: An ad for laundry detergent. X: Surf removes dirt and odors. Y: Surf removes all dirt and odors. Z: Surf removes a lot of dirt and odors.
Scenario: Ad for gum • Four out of five dentists surveyed recommend Trident for their patients that chew gum.