Semantics 2

Semantics: Meanings of Words and Sentences

• There are two components of meaning:
1. Meanings of the parts (lexical meaning)
2. Meanings of the combinations (phrase meaning)

Pragmatics and Semantics

• There is a continuum between Semantics (things that are true by the DEFINITIONS and RULES) and Pragrmatics (things that are true by virtue of the REAL WORLD).
• Consider the following sentences:
• The rock ate my lunch.
  Semantically false, because "eat" requires an ANIMATE subject.
• The giraffe ate the hyena.
  Grey area, does SEMANTICS include the concept VEGETARIAN??
• The giraffe ate one hundred pounds of grass today. Pragmatics, how much DOES a giraffe eat in a day?

Lexical Meaning

• Each one of us knows thousands of words. Some of these words have very complicated meanings. We feel that these words can be defined in terms of "simpler" words.
• An "assassin" is "someone who kills someone who is prominent"
• We can take this idea further and develop a conception of SEMANTIC FEATURES which encode the CORE PROPERTIES of words. Since the semantic features cover only core properties, they will NOT capture every nuance of meaning.
• For example FEMALE and HUMAN are characteristics shared by words such as "woman", "mother", and "widow".
• FEMALE and NONHUMAN characterize "lioness", "ewe" and "mare".
• The border between including a concept in the definition and not doing so can be very fuzzy.
• "bachelor = UNMARRIED (ADULT) (HUMAN) MALE
• "The most eligible bachelor I know is that ____"
1. two-year old
2. priest
3. divorced man
4. widower
• The quality of NEVER-MARRIED and MARRY-ABLE might be part of the meaning as well.
• Verbs have semantic features too, giving classes of verbs such as:
• motion -- "walk", "arrive", "leave"
• sensation -- "taste", "feel", "see"
• propositional attitude -- "believe", "know"
• There is abundant psychological evidence for semantic features:
• Slips of the tongue:
  "bridge of the neck (nose)" (body parts)
  "he came too early (late)" (time)
  "the lady with the VW (dachshund)" (SMALL and GERMAN)
• Semantic Features are NOT based on scientific/biological taxonomies.
• Rather, items are often classified with respect to HUMANS.
• For example relative size, bigger/smaller than a human being.
• Or, whether something is dangerous to human beings.
• There is little (if any) evidence for semantic features for MAMMAL (including whales especially) or RODENT (biologically defined as a subclass with the special characteristic of ever-growing teeth).
• Thus, though for SCIENTIFIC purposes (biology, etc.) we make up categories such as MAMMAL and RODENT to explain facts of species and evolution, these categories do NOT necessarily plan a role in the cognitive (mental) classification of animals.
• Some semantic feature IMPLY the presence of others:
  HUMAN ==> ANIMATE
  ANIMATE ==> NOT ABSTRACT
• Verbs and adjectives encode features of their ARGUMENTS:
  "swim" -- medium is a liquid
  "splash" -- object is a liquid
  "viscous" -- object is a liquid
• Likewise, we know whn actions or properties are incompatible, thus one cannot "cut" a liquid or "bend" a liquid.

Synonyms and Homophones

• Two words with the same semantic features (meaning) but which sound different are called SYNONYMS (e.g. "sofa"/"couch").
• Two words that sound (or are spelled) the same but which have different semantic features (meanings) are called HOMONYMS or HOMOPHONES (e.g. "bear"/"bare").
• One word with multiple related meanings is called POLYSEMOUS.
• In practice it can be difficult to distinguish homophony from polysemy.
• Homonyms are one source of AMBIGUITY. One sentence can be understood in different ways if the meaning of one of the words changes.
• "He hit the bat with the ball."
  bat1 -- the flying animal
  bat2 -- baseball bat
• "She cannot bear children."
  bear1 -- give birth to
  bear2 -- tolerate
• Polysemous words can also lead to ambiguity:
  marry1 -- to take as a spouse
  marry2 -- declare to be marry1-ed
1. Jane marry1-ed Bill.
2. Jane and Bill marry1-ed.
3. Lanny marry2-ed Jane and Bill.
4. Lanny marry2-ed Jane.
• So "X married Y" is ambiguous between marry1 and marry2.
• Consider the following sentences:
  John sold the house to Bill.
  John sold the house.
  Bill bought the house from John.
  Bill bought the house.
• Now consider the analogous sentences for renting instead of buying, with John and Bill playing the analogous roles again:
  John rented the house to Bill.
  John rented the house.
  Bill rented the house from John.
  Bill rented the house.
• Thus, "X rented the house" is ambigous in a way which "buy"/"sell" are not.
• Synonyms are different words with the same (or similar) meaning.
• Some people claim that there are no perfect synonyms, by which they mean words X and Y such that every sentence with X can be changed to a sentence with Y without changing the meaning. But this is too strong a requirement, because it requires ALL meanings of X and Y to be the same, and ALL grammatical properties of X and Y to be the same.

Antonyms

• ANTONYMS are NOT words with totally different meanings. Rather they are words which are different along ONE DIMENSION.
• For example, "bachelor" is ADULT UNMARRIED HUMAN MALE.
• The antonym of "bachelor" is NOT a NONADULT MARRIED NONHUMAN FEMALE.
• One possibility for an antonym for "bacholor" is "husband", changing only the UNMARRIED feature.
• Another possibility would be to change the MALE to FEMALE, giving "spinster".
• Changing ADULT or HUMAN do not seem to yield antonyms, leading us to speculate that the features might be more or less SALIENT.
• There are several kinds of antonyms:
1. Complementary pairs (X, not X)
   dead/alive, awake/asleep
2. Gradable pairs (opposite sides of a scale)
   hot/cold, big/small
   Such pairs seem to be approximately samne magnitude from the middle, warm/cool.
   Usually one end of the scale is less marked--
   How tall is he? (no implication)
   How short is he? (implies that he IS short)
3. Relational opposites (opposite roles in a relation)
   teacher/pupil, employer/employee, buy/sell

Names

• Naming is not only a linguistic function, many other factors are involved.
• There are very few real constraints on names.
• Anything Goes
• The The
• UB40
• Toad the Wet Sprocket

Meanings in Combination

• The meanings of combinations of words is largely a product of the conbinations of the meanings of the words.
• meaning(A + B) = meaning(A) + meaning(B)
• However, since some words have NEGATIVE meanings, the meaning of the composite can get complicated.
• Some adjectives have a meaning that is largely independent of the noun that they modify. One example is color words--
  a red balloon
  a red house
  are both "red" in the same way.
• Other adjectives (for example size words) have a context (prototype) set up by the noun, and the adjectives compare to the prototype--
  a big balloon
  a big house
  As someone said, a big mouse is still smaller than a small elephant.
• As in morphology the HEAD sets up the main component of meaning and the context modifies the meaning--
  a bluebird -- a type of bird
  a house with a white picket fence -- a type of house
  John sold the house to Bill -- an event of selling

Thematic Roles

• In the case of sentences, the parts of the sentence play specific roles in the meaning, as determined by the verb.

·         John put the book on the table

·         ====     ======== ============

·         Agent    Theme    Goal (a Location)

• The themeatic roles for "put" are Agent (for the subject), Theme (for the object) and Goal (for the prepositional phrase).
• Notice that the PP must be of the correct type:
  *John put the book in the morning.
  *John put the book at five o'clock.
• Some thematic roles:
• Agent -- doer of action
• Theme -- thing done to
• Location -- place
• Source -- original place
• Goal -- destination place
• Instrument -- something that aids Agent in doing
• Another example:

·         The boy carried the red brick from the wall to the wagon.

·         =======         ============= ============= ============

      Agent           Theme         Sourc         Goal