2. Introduction
Sometimes, semantic relation are the result
of particular words in a sentence, but in
other cases the relations are the result of
syntactic structure
Based on the notion of truth, we can see
the semantic relation of entailment and
presupposition
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3. Entailment [1]
It is a relation between propositions one of which
necessarily follows from the other.
For example
a. The anarchist assassinated the emperor.
b. The emperor died.
a is said to entail b
Entailment is not an inference in normal sense. We just
know it instantly because of our knowledge of a
language, e.g. English.
Entailment defined by truth:
A sentence p entails a sentence q when the truth of the
first (p) guarantees the truth of the second (q), and the
falsity of the second (q) guarantees the first (p).
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4. Entailment [2]
Thus, the composite truth table for entailment is
p q
T T
F T or F
F F
T or F T
The source for entailment may be lexical (on the
example) or syntactic.
a. The Etruscans built the tomb.
b. This tomb was built by Etruscans.
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5. Presupposition [1]
It is relation between propositions by which a
presupposes b if a to have truth value, b must be true.
It is what a speaker assumes is true or known by the
hearer.
e.g. your brother is waiting.
P you have a brother.
In some respects presupposition seems like entailment: a
fairly automatic relation, involving no reasoning, that
seems free of contextual effects. In other respects
though, presupposition seems sensitive to facts about
context of utterance.
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6. Two approaches to presupposition
1. In the first approach, sentences are viewed as
external objects. Meaning is seen as an
attribute of sentences rather than something
constructed by participants (semantics).
2. The second approach views sentences as the
utterances of individuals engaged in a
communication act (pragmatics).
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7. Presupposition [2]
Presupposition as a truth relation.
If p (the presupposing sentence) is true then q (the
presupposed sentence) is true. If p is false, then q is still
true. If q is true, p could be either true or false.
A composite truth table for presupposition
p q
T T
F T
T or F T
One of the tests to check for the presupposition
underlying sentences involves negating a sentence with
a particular preposition and considering whether the
preposition remains true.
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8. Types of Presupposition
Type Example Presupposition
Existential The X >> X exists
Factive I regret leaving >> I left
Non-factive He pretended to be happy >> He wasn’t happy
Lexical He managed to escape >> He tried to escape
Structural When did she die? >> she died
Counterfactual If I weren’t ill, >> I am ill
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9. Presupposition Failure
Presupposition Failure happens when there is
no referent for the nominal. Thus, there is truth
value gap.
e.g. The king of France is bald.
P There is a king of France. ??
Other types of presupposition are produced by
particular words or construction, which
together are sometimes called presupposition
triggers.
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10. Presupposition Triggers
Syntactic Structure
e.g. a. It was his behavior with frogs that disgusted me.
b. Something disgusted me
Subordinate Clause
e.g. a. I was riding motorcycle before you learned to walk
b. You learned to walked.
Lexical triggers
e.g. a. Sheila regretted eating the banana
?? b. Sheila considered eating the banana
c. Sheila ate the banana.
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11. Presupposition and Context
Often presuppositional behavior seems sensitive to context.
e.g. 1. She died before she finished her thesis
She hasn’t finished her thesis
2. She died before she finished her thesis
She finished her thesis
The presupposition is blocked or cancelled by our general knowledge of the world.
This characteristic is known as defeasibility
The same phenomenon is found with intonation, where stressing different parts of
the sentence can produce different presuppositions.
a. Alice loved HARRY Alice loved someone
b. ALICE loved Harry. Someone loved Harry
Projection problem can also cancel a presupposition. Sometimes the presupposition
produced by a simple clause does not survive when the clause is incorporated into
a complex sentence.
a. John will regret doing linguistics
b. John is doing/will do linguistics
c. If John does linguistics, he’ll regret it.
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