Understanding meaning involves knowledge about the truth value of sentences relative to situations.
Example Sentence: (1) "King Henry VIII snores."
The truth value of this sentence is context-dependent; it cannot be classified as genuinely true or false without reference to the state of the world.
At present (early 21st century), the sentence is false, as King Henry VIII died in 1547 AD.
Conversely, it may have been true in 1525 AD, highlighting that total knowledge of all situations is unattainable for most speakers.
Knowing a sentence's meaning implies an understanding of the situations wherein the proposition would be true:
Definition (2): “To know the meaning of a [declarative] sentence is to know what the world would have to be like for the sentence to be true.” (Dowty et al. 1981)
Concept of Proposition:
A proposition is a claim about the world, potentially true or false in various situations.
Some scholars argue that grammatical entities (sentences) do not hold truth values; only propositions do.
A speaker makes a true statement when the meaning of their sentence aligns with the state of affairs.
Using sentences as true or false is considered an imprecise way of speaking since the truth belongs to the propositions they express.
3.2 Analytic Sentences, Synthetic Sentences, and Contradictions
Understanding sentence meaning enables us to determine truth conditions.
Analytic Sentences (Tautologies):
These sentences are true under all circumstances, meaning they hold no informative power regarding the world.
Examples (3):
(3a) "Today is the first day of the rest of your life."
(3b) "Que será será."
(3c) A statement by Sen. Olympia Snowe regarding a health care reform vote highlights the tautological nature of some expressions.
Despite being non-informative, tautologies are used in speech for their communicative value, stemming from the pragmatic inferences they generate.
Contradictions:
Propositions that can never be true. Example (4): “And a woman who held a babe against her bosom said, 'Speak to us of children…'”
Synthetic Propositions:
Can be true or false depending on context; these form the majority of declarative sentences.
An effective semantic analysis should explain why certain sentences are analytic or contradictory.
3.3 Meaning Relations Between Propositions
Consider the pair of sentences (5):
(5a) "Edward VIII has abdicated the throne in order to marry Wallis Simpson."
(5b) "Edward VIII is no longer the King."
Entailment:
The truth of (5a) logically necessitates the truth of (5b).
Properties of entailment:
Whenever proposition p is true, q must be true.
If q is false, then p must also be false.
These relations derive from the meanings of p and q, independent of context.
Example (6):
(6a) "I broke your Ming dynasty jar."
(6b) "Your Ming dynasty jar broke."
The relationship confirms that (6a) entails (6b).
Mutual Entailment:
Sentences that mutually entail each other are synonymous (7).
(7a) "Hong Kong is warmer than Beijing (in December)."
(7b) "Beijing is cooler than Hong Kong (in December)."
Inconsistency and Compatibility:
Incompatible propositions cannot both be true. Contradictions always hold opposing truth values.
Example (8):
(8a) "Ringo Starr is my grandfather."
(8b) "Ringo Starr is not my grandfather."
Contrary propositions may both be false in certain contexts but can’t co-exist as true (9).
Independent propositions:
Neither entail nor contradict each other, having an independent truth value.
3.4 Presupposition
Definition of Presupposition:
A statement that implies the truth of another statement or conveys information assumed to be shared in conversation.
Common Ground:
Refers to shared knowledge between speaker and hearer, including general world knowledge or information mentioned previously in conversation.
Trigger for Presupposition:
Certain words or grammatical constructions trigger presuppositions.
Example (10):
In the interaction between the March Hare and Alice, the use of “more” presupposes Alice had tea previously.
Presupposition Failure:
If the presupposition is incorrect (Alice had no tea), it leads to confusion or offense.
Identifying Presuppositions:
Unlike entailments, presupposed information remains unaffected by whether the speaker asserts, questions, or denies the truth of the presupposing statement.
For example, all variations of (11) imply the vice president falsified his dental records, highlighted by the presence of "regret."
Family of Sentences Test:
This test shows that presuppositions persist under negations and questions, unlike entailments, which do not.
Example (12a) presupposes that Susan has been dating an Albanian monk, with the presence of "stop."
Testing Presupposition Failure:
If a presupposition fails, the hearer may challenge it by expressing confusion about the claim (13).
Common Presupposition Triggers:
Definite Descriptions:
E.g., "the King of France" presupposes a unique entity exists.
Factive Predicates:
E.g., "regret, aware, realize" necessitate their complements be true.
Implicative Predicates:
E.g., "manage to presupposes try" underlines an underlying condition.
Aspectual Predicates:
E.g., stop presupposes duration of the event discussed.
Temporal and Relative Clauses:
The truth of subordinate clauses must hold true as part of the presupposition.
Comparisons:
E.g., comparative sentences bring in assumptions of known qualities.