Semantics, part 2

December 3, 2012

And Then There Were Three• Course Evaluations at the end of today’s lecture!

• Semantics/Pragmatics homework still due on Wednesday

• I will also pass out a final exam review checklist on Wednesday

• Wednesday: some comments on language preservation

• Friday: an opportunity to ask some review questions

• Semantics homeworks will be graded by Friday

Meaning Review• Referent: the actual thing in the world an expression picks out.

• Extension: a set of referents (= a predicate) in some possible world.

• Sense: what an expression refers to in all possible worlds.

• Truth: a proposition is true if the referent of its subject is contained in the extension of its predicate.

• Meaning:

• The meaning of a proposition is the set of conditions in which that proposition is true.

• Truth conditions

Compositionality• By the way:

The idea that the meaning of a sentence can be calculated from the meaning(s) of its parts is the principle of compositionality.

• Consider this sentence:

The President of the United States is a white male.

• Is this true? How do you know?

• How about this sentence:

Santa Claus is a white male.

Types of Sentences

• Propositions may be distinguished on the basis of the kinds of worlds in which they may be true.

1. Synthetic propositions may be true or false, depending on the state of affairs in the world.

2. Analytic propositions are always true, no matter what the state of the world.

3. Contradictions are always false, no matter what the state of the world.

• Quick Write check.

Moving On (Again)• There are several different ways to study meaning in

language:

1. Pragmatics

The meaningful use of linguistic expressions in conversation and discourse.

2. Compositional Semantics

How the meaning of phrases and sentences is built up from the meanings of individual words.

3. Lexical Semantics

The meaning of individual words, and how they’re related to one another.

Lexical Semantics• Here are two basic meaning relationships that words

can have with one another:

1. Synonymy

• Two words have the same meaning

• couch/sofa, groundhog/woodchuck, hide/conceal

• = real-world extensions are identical

2. Hyponymy

• one word’s extension is a subset of another word’s extension

• poodle/dog, laptop/computer, gas giants/planets

Synonym Schematic

Fido Marmaduke Garfield

Rex

Spot Snoopy

Fifi Mr. Meowser

Lassie

Scooby The Death Star

is a dogis a canine

canines and dogs are synonyms

Hyponym Schematic

Fido Marmaduke Garfield

Rex

Spot Snoopy

Fifi Mr. Meowser

Lassie

Tinkerbell The Death Star

is a dogis a poodle

poodle is a hyponym (subset) of dog

Another One• Antonymy: when words that mean the “opposite” of each other

• Complementary antonyms:

• Everything in the world is one or the other

• unmarried/married, present/absent, visible/invisible

• Relational antonyms:

• Reflect a symmetrical connection between each other

• give/receive, buy/sell, teacher/pupil

• employer/employee, adviser/advisee

• Scalar antonyms: words form two ends of a scale

• hot/cold, happy/sad, big/small, fast/slow

Homonyms/Homophones• Homonyms/Homophones are words with:

• same pronunciation

• unrelated meanings

• from Greek: /homo-/ “same” + /onyma/ “name”

• Examples:

• trunk (of an elephant), trunk (chest), trunk (of a tree)

• also: bear, bare

• Homonyms can create ambiguity:

• We saw her duck.

Polysemy• Polysemy is when one word has several different, but related meanings.

• From Greek: /poly-/ “many” + /sema/ “signal”

• Examples:

• Mouth of a river ~ mouth of an animal

• A baseball diamond ~ a geometric diamond ~ a diamond stone

Intersection• Compositional semantics, continued...

• We have discussed how the referents of nouns and the extensions of predicates get put together to form a meaningful proposition.

• Now let’s consider adjectives and nouns in noun phrases.

• Simplest case: pure intersection

• black dogs =

• the set of all dogs

intersected with

• the set of all black things

Pure Intersection Schematic

Marmaduke

Odie Charcoal

Lassie Spot

Rex Darth Vader

Spuds

Oil

dogsblack dogs

black things

Pure Intersection of Geekery

Semantic Features• Idea: the meaning of a word can be precisely determined by the pure intersection of predicates of which it is a hyponym (subset).

• Example: “square”

[TWO-DIMENSIONAL, FOUR-SIDED, EQUAL-SIDED]

• Example: “bachelor”

[HUMAN, MALE, UNMARRIED]

• The predicate sets form a word’s semantic features

• “hen” and “mare” share the feature [FEMALE]

• “bachelor” and “woman” share the feature [HUMAN]

Verb Features• The same semantic feature can be expressed by a variety of different verbs.

• Example: the feature [GO]

• reflects a change in position

• fly, walk, roll, stumble, run, crawl, etc.

• More subtle examples of [GO]:

• give: “John gave Mary an engagement ring.”

John Mary

ring

• “The boy threw the ball over the fence.”

A Syntax Flashback• Remember that, in syntax, we learned that different verbs require specific complement structures.

• For instance, transitive verbs require an object NP in their verb phrases.

I devoured the sandwich.

I met the Professor.

• Similarly, ditransitive verbs can take two objects in their verb phrases.

The dog trainer sold me a chew toy.

Larry gave Shelly the textbook.

Syntax/Semantics• There are sub-features of [GO], which are reflected in constraints on verb complements in English.

• [BALLISTIC]: a one-time [GO] V’ V NP NP

• [SUSTAINED]: a continuous [GO] *V’ V NP NP

• Ballistic Verbs Sustained Verbs

throw the boy a ball *push the boy a ball

toss the boy a ball *pull the boy a ball

kick the boy a ball *lift the boy a ball

fling the boy a ball *drag the boy a ball

Role-playing• The objects of ditransitive verbs can be expressed in two different syntactic ways:

Larry gave Shelly the textbook. (NP NP)

Larry gave the textbook to Shelly. (NP PP)

• Despite the syntactic differences, each noun plays the same role in both sentences:

Larry: Agent (the entity performing the action)

Textbook: Theme (thing being acted upon)

Shelly: Recipient (being coming into possession of something)

Thematic Roles• Verbs have semantic requirements.

• For a sentence to make sense, it has to include nouns which can play the roles required by the verb.

• give: Agent; Theme; Recipient

Larry gave Shelly the textbook.

Larry gave the textbook to Shelly.

Shelly was given the textbook by Larry.

!Anger gave Shelly the textbook.

Other Thematic Roles• Experiencer

• = animate being that has a perceptual or mental experience.

• Ex: Susan heard the music.

• Source

• = the origin of a change.

• Ex: Jan arrived from Detroit.

• Instrument

• = the means used to accomplish an action (not agent)

• Ex: The hammer cracked the window.

Other Thematic Roles• Goal

• = the end point of a change in location or possession.

• Ex: Chris hitchhiked to Alaska.

• Location

• = the place where an action occurs.

• Ex: Neil Young played a show in Winnipeg.