Semantics

What Is Word Meaning?

Dictionary definitions

• Who decides what words mean?
• Can the meanings of words be expressed in English (Chinese, etc.) sentences?
• How do we know what the meanings of the words in the definitions are?

Mental images

• Are people's images for words the same?

Prototypes

• What about members of a category which differ significantly from the prototype?

Reference

• What about words for the referents do not exist?
• What about different expressions with the same referent?
  Mary wanted to know if Boris Yeltsin was the current President of Russia.

Sense, as opposed to reference

• We need an account of the meaning of expressions like the current President of Russia, the current King of France, and a world in which pigs can fly.

Semantic decomposition

• Can the meaning of a word be described in terms of a set of primitive semantic features?

Rules about meaning

• If something is swimming, it is in a liquid.
• If something is open, it is not closed.
• If something is [+human], it is [+animate].
• If and only if x owns y, then y belongs to x.

Necessary and sufficient conditions

• If something is a horse, what do you know about it?
• What things must be true of a thing in order for you to call it a horse ?
• Is it possible in general to arrive a set of necessary and sufficient conditions for the meaning of a word?

More typical and less typical features

• What are the typical features of a horse?

Semantic relations

• Can the meanings of words be expressed in terms of their relations with other words?
• Synonyms, complementary pairs, relation opposites, reversal pairs, hyponyms, transitive/intransitive pairs

Context-freeness

• Is it possible to specify the meaning of a word independent of its linguistic context?
• a red brick, red hair, a toy gun

Literal and figurative meaning

• Is it possible to separate the literal meanings of words from the figurative?
  • The rock hit me like a bolt out of the blue.
  • The idea hit me like a bolt out of the blue.
• Idioms: should they simply be stored as separate lexical items along with their (idiomatic) meanings?
  • Mary spilled the beans.
  • Jack kicked the bucket.

Polysemy, ambiguity, and indeterminacy

• How many meanings does a word such as give have? The sentence the priest married my sister seems to be ambiguous.
• What about eat in Mary ate a cucumber and Mary ate a noodle?
• Indeterminacy is an alternative to polysemy.

Meanings of particular parts of speech (syntactic categories)

• Noun meanings: things
  • Proper nouns and common nouns: individuals and types
  • Mass and count nouns
• Verb meanings: relations
  • Number and kinds of arguments
  • Arguments that are obligatory in the syntax vs. those that aren't
  • Transitivity
  • Causitive
• Adjective meanings: properties

An overview of formal semantics

• Compositionality revisited
• Reference (extension)
• Syntactic rules and associated semantic rules
  • NP: individual
  • VP: set of individuals
  • S: truth value
• Interpretation of a declarative sentence: determining its truth conditions
• Identity statements
• Belief and opaque contexts
• Possible worlds
• Sense (intension)
  • NP: function from possible circumstances to individuals
  • VP: function from possible circumstances to sets
  • S (propositions): function from possible circumstances to truth values
• that complements of verbs like believe refer not to a truth value but to the set of circumstances in which the embedded sentence is true
• Quantification
  • Ambiguity: Every student took a test.
  • There is a test T, such that for each student S, S took T.
    For each student S, there is a test T, such that S took T.
• Adjective meaning
  • Intersection: blue
  • Relative intersection: big
  • Anti-intersection: fake

Acquisition of Word Meaning

• Some features of the acquisition process
  • Complexive concepts
  • Overgeneralization
  • Underextension
  • The Naming Explosion (last half of second year)
  • Rapidity of word learning following the Naming Explosion: approximately 9 words per day for several years
  • The Shape Bias
  • Dimension adjectives: context specificity and failure to infer relations among words ("if A is larger than B, then B is smaller than A")
• "Poverty of the stimulus" for word learning: multitude of meanings possible given a word and a context
• One account: children are born making particular assumptions.
  • Labels refer to whole objects rather than their parts.
  • Nouns refer to taxonomic categories not to classes associated by thematic relations.
  • Each object has only one label.
  • Every two forms contrast in meaning.
• Another account: rich input in combination with statistical learning mechanism is powerful enough to do without innate assumptions