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Towards a Semantic Lexicon Jerry A. Fodor & Ernie Lepore James Pustejovsky . References Pustejovsky, J. (1991). The syntax of event structure. Cognition , 41 , 47-81. Pustejovsky, J. (1995). The generative Lexicon . Cambridge, MA: MIT Press.
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Towards a Semantic Lexicon Jerry A. Fodor & Ernie Lepore James Pustejovsky
References • Pustejovsky, J. (1991). The syntax of event structure. Cognition, 41, 47-81. • Pustejovsky, J. (1995). The generative Lexicon. Cambridge, MA: MIT Press. • Fodor, J. A., & Lepore, E. (1998). The emptiness of the lexicon: Reflections on James Pustejovsky’s “The Generative Lexicon”. Linguistic Inquiry, 29, 269-288. • Pustejovsky, J. (1998). Generativity and explanation in semantics. A reply to Fodor and Lepore. Linguistic Inquiry, 29, 289-311.
Structure of Presentation • The two approaches: Theoretical starting points/assumptions and proposals for lexical semantics. 1a) Fodor & Lepore 1b) Pustejovsky • Criticism and responses 2a) - Fodor & Lepore against Pustejovsky - Pustejovsky against Fodor & Lepore 2b) Central themes: analyticity & compositionality
1a) Fodor & Lepore: Theoretical assumptions i. Lexicalatomism: Lexical entries lack internal structure. ii. Denotationalsemantics: the only thing a lexical entry specifies is the denotation of the item it describes : the lexical entry for dog says that it refers to ‘dogs’. iii. Compositionality: the meaning of a phrase is always a function of the meanings of its lexical constituents. The problem of compositionality: how lexical semantics contributes to determining the semantic interpretation of phrases?
• want a beer = ‘want to have a beer’ • drink a beer = ‘drink a beer’ How does the theory that derives the meanings of phrases from the meanings of their lexical constituents ensure this difference of interpretation? Sense Enumeration Lexicon (SEL): two wants, differing somehow in meaning, one of which takes an infinitival complement and one of which takes an NP. But such treatment would miss the equivalence: if Bill wants to drink a beer and Mary wants a beer, they both want something and they both want to have something. So, how are we to handle want avoiding lexical polysemy?
Want denotes a relation which is the same whether its complement is an infinitive or a NP. This is the relation that holds between x and y when and only when x is a creature & y is a state of affairs, and x want y. This way want NP and want INF get the same semantic values without us having to assume two lexical entries. But the question remains: how does a compositional semantics operate to assign the interpretation ‘wants to have NP’ to expressions of the form want NP?
A lexical entry is allowed to be complex. If it is, it specifies: • the meaning (content, denotation) • a rule of composition that contributes to determining the logical form of the phrases of which the item is a constituent. (Contrary to pure compositionality,) The logical role of an expression can be determined by the lexical entries of the forms that govern it; beer is the logical object of drink in want to drink a beer, but it is the logical object of have in want a beer.
Schematic derivation of the interpretation of expressions of the form wants X (where X is a lexical item). The semantic interpretation proceeds, node by node, from the bottom to the top of the syntactictree. Domain ·VP VP··NP wants x Stage 1 Input: <wantsV, XNP> Operation: Assigns lexically specified semantic interpretations. Output: Interpretations of assignments of denotations to the lexical nodes: assigns to the V node the set of ordered pairs <y,x> such that y wants x, and to the NP node the lexically specified denotation of X. Stage 2 Input: The domain tree with the lexical nodes interpreted as per stage 1. Operation: Interprets the node VP. Output: VP is assigned ‘{y: y wants to have F(X)}’ where F(X) designates the interpretation that X receives in stage 1.
Note: We assume that the operation in stage 2 is driven by a composition rule that is part of the lexical entry for want: namely, if the constituents of VPi are <wantsV, XNP>, then the interpretation of VPi is ‘want to have F(X)’. Such complex lexical entries would preserve an atomistic lexical semantics of denotations (as opposed to a lexical semantics of complex structures). Want does not denote anything except a relation between a creature and a state of affairs (its content is absolutely context invariant). There can be context effects on what a lexical item contributes to logical form but not on what it contributes to content.
1b) Pustejovsky’s Theory of Generative Lexicon Theoretical Starting Points: The human conceptual apparatus (i.e. the ability to categorize and represent the world) is one of generative categorization and compositional thought (as opposed to extensional). The human linguistic capacity reflects our ability to categorize and represent the world in the particular ways we do. Therefore, language is a natural manifestation of our generative construction of the world through the categories it employs.
Linguistic reality to be accounted for: Finite lexical resources able to convey the richness and diversity of meaning (meaning is dirty). Traditional view: fixed meanings can serve countless purposes. (sense enumeration lexicon) Generative view: the semantic features change in context. Words undergo semantic modification and modulation with respect to the context of use.
Polysemy a key aspect to linguistic creativity and a window into the generative nature of thought. (1)a. Mary doesn’t believe the book. b. John sold his books to Mary. (2)a. Eno the cat is sitting on yesterday’s newspaper. b. Yesterday’s newspaper really got me upset. (3)a. Mary is in Harvard Square looking for the Bach sonatas. b. We won’t get to the concert until after the Bach sonatas. (4)a. I have my lunch in the backpack. b. Your lunch was no longer today than it was yesterday. (5)a. The phone rang during my appointment. b. My next appointment is John.
A Semantic Lexicon needs to account for semantic compositionality: what contribution lexical information makes toward the overall semantic interpretation of sentences. (the meaning of the whole is a function of the meaning of the parts, words play an active role in meaning determination) A lexical entry should provide for: • the basic content meaning of the word (basic meaning derived meaning generatively produced) • the different meanings the word might acquire in different contexts • the compositional emergence of new senses • the syntactic forms predicted by the semantics of the word.
(methodological starting points) • Empirical investigation: the theory must connect to the observables = the range of polysemies a word exhibits. II. Development of the theory to describe observables satisfying simplicity at the same time = a mechanism of recursive generative devices able to explain the semantic adaptation of the word.
Generative Lexicon • A lexical entry models the meaning of a word by means of a semantic typing system encoding generative factors. • Compositional rules sensitive to the contextual determination of a word’s meaning operate on its semantic structure. (type coercion, subselection, co-composition)
The semantic typing system involves at least four basic levels of linguistic representation: 1. Argument Structure: Specification of number and type of logical arguments. 2. Event Structure: Definition of the event type of an expression and its subeventual structure. 3. Qualia Structure: A structural differentiation of the predicative force for a lexical item. 4. Lexical inheritance structure: Identification of how a lexical structure is related to other structures in the type lattice.
Word meaning is structured on the basis of four generative factors, called qualia roles, that capture how humans understand objects and relations in the world and provide the minimal explanation for the linguistic behavior of lexical items. FORMAL: the basic category that distinguishes an object within a larger domain CONSTITUTIVE: the relation between an object and its constituent parts TELIC: the object’s purpose and function AGENTIVE: factors involved in the object’s origin or ‘coming to being’
A schematic description of a lexical item a: a ARGSTR= ARG1= x ……… QUALIA= CONST = what x is made of FORMAL = what x is TELIC = function of x AGENTIVE = how x came into being
The qualia structure is at the core of the generative properties of the lexicon, since it provides a general strategy for creating increasingly specific concepts with conjunctive properties. Semantic types should be discriminated in a way that also accounts for their grammatical behavior; in other words, semantic well-formedness should be accounted for. For example, take rock and chair. Functionality (i.e.TELIC) plays an important role for the individuation of chair – being an artifact_object – but not for rock – being a natural_kind – (functionality undefined). This is reflected in grammatical behavior: a good chair, enjoy the chair but *a good rock, *enjoy the rock. EXCEPTION: The climber enjoyed that rock is well-formed. Rock itself takes on a new meaning, by virtue of having telicity associated with it, and this is accomplished by co-composition with the semantics of the subject NP.
Nominal Polysemy Nominal types in natural language: (i) non-polysemous (food) (ii) polysemous (lunch) Conventional semantic treatments would fail to account for the distinction between these two types of nominals. Whereas the meaning of our concept of food can be minimally captured by the intersective property of ‘edible substance’, a similar treatment would fail to account for lunch being a more complex concept since it also refers to a specific period of or event. What is the treatment proposed by the Generative Lexicon Theory?
(i) The Generative Lexicon Theory proposes to separate the characteristic property (FORMAL role) from the functional aspect (TELIC role) of the notion of food. Food is a concept making reference to distinct and orthogonal facets of knowledge, each expressing a different explanation of this concept. We can represent our analytic knowledge associated with food by conjoining or unifying ‘orthogonal’ values from and qualia roles. Such a structure is called a unified type. This method permits a general strategy for creating increasingly specific concepts with conjunctive properties. (Unified types can be seen as structured by orthogonal dimensions or perspectives, rather than as inheriting properties from multiple parents in a homogeneous property structure.)
Schematic Representation food ARGSTR = [ARG 1 = x:substance] QUALIA = FORMAL = x TELIC = eat(e,y,x) Let PFand QTbe the values associated with the FORMAL and TELIC qualia respectively and analyze the orthogonal values of the qualia roles as logical conjunction: λx[PF(x) QT(x)]. For the interpretation of the noun food, this would give the expression: λx[substanceF (x) λyλe [eatT (e,y,x)]]
A concept is semanticallywell-formed only if it inherits from a single parent within a given quale. Generative Lexicon Theory assumes that there is no multiple inheritance per se in natural language semantics. What appears to be instances of concepts that inherit from multiple superordinates are in fact either types orthogonal inheritance structures or complex types. • Simple unified types: simple conjunctive typing or interpretation • Complex unified types: more than one senses, therefore, contradictory types ‘denoted’ as multiple inheritance seems to be involved.
(ii) Complex types or dot objects. A dot object is a deeper structure relating the apparently contradictory senses of the word. For each sense pair there is a relation that ‘connects’ the senses in a well-defined way. The dot object is characterized as: - a Cartesian type product of n types (the product τ1xτ2, of types τ1and τ2, each denoting sets, is the ordered pair <t1, t2>, where t1 ε τ1 ,t2 ε τ2) • with some additional constraints: there exists a relation R between the elements of τ1and τ2 , namely, R(t1, t2). This relation must be seen as part of the definition of the semantics for the dot object.
Type combinations included in the broad range of complex types encountered in natural language: a. phys_objinfo : e.g., book, record b. eventevent : e.g., construction, examination c. eventquestion : e.g., exam d. eventfood : e.g., lunch, dinner e. eventhuman : e.g., appointment For each of these type products, there is a unique relation, Ri, that structures the types. For example, nouns such as book or record, are structured by a containment relation R (container-like concepts). This containment relation -hold(x,y)- must be encoded directly into the semantics of the concept as the FORMAL quale value.
The lexical structure for book as a dot object is represented as follows: book ARGSTR = ARG1 = y:information ARG2 = x:phys_obj QUALIA = informationphys_obj FORM = hold(x,y) TELIC = read(e,w,xy) AGENT=write(e,v,xy) This translates to the following logical expression: λx yev[book(x:physobj y:info) hold(x,y) λwλe [read (e,w,xy) [write(e;v,x y)]]
Verbal Polysemy The distinction between syntactic and semantic polysemy is largely arbitrary and difficult to maintain. Syntactic polysemy deals with polyvalency (I), object deletion (II) and the general properties of argument expression (III). (I) a. Mary began to read the novel. b. Mary began reading the novel. c. Mary began the novel. (II) a. Mary ate (her meal) quickly. b. Mary devoured *(her meal) quickly. (III) a. John carved a doll (out of the wood). b. John carved the wood (into a doll).
Semantic polyvalency deals with different but related senses of a verb. (I) a. Mary enjoyed the movie last night. b. John enjoys his morning coffee. c. Bill enjoyed Kundera’s last book. (II) a. John opened the door. b. Mary opened the letter.
Examples where two dimensions of the linguistic behavior of verbs are being modulated: (a) the arity of the verb complex, (b) the meaning of the verb itself. Polysemy as both syntactic variation in the complement structure and semantic mutability effects in the verb. (I) a. John gave a talk to the academy today. b. John gave a talk today. c. *John gave a book today. (II) a. Mary showed a movie to her guests. b. Mary showed a movie. c. *Mary showed a record. what is it about the meaning of the nouns talk and movie that allows a reinterpretation of (i.e., co-composition with) the verb meaning in each example?
Generative Lexicon Theory provides an explicit model for how meaning shifts and polyvalency phenomena interact. The qualia structure provides the structural template over which semantic transformations (=generative devices such as co-composition, typecoercion and subselection) may apply to alter the meaning of a lexical item or phrase. • John used the knife on the turkey. • Mary used soft contact lenses since college. • This car uses unleaded gasoline. The verb use is semantically underspecified. The factors allowing us to determine which sense is appropriate for any of these cases are twofold: a) the qualia structures for each phrase in the construction b) a richer mode of composition, which is able to take advantage of this qualia information.
It is an empirical question as to how much of the syntactic behavior of a lexical item is determined by the semantic type. a. John read a book. (Read permits complements of type b. John read a story. physical_object as well as complements c. *John told a book. of type information. Tell uniquely for complement that is of type information.) Verbs of transfer: • both directions of transfer, e.g. get, rent. a. John got a book for Mary. (give) b. John got book from Mary. (take) - specified directionality of transfer, e.g. give, sell.
2a) Fodor & Lepore against Pustejovsky Arguments for the complexity of lexical entries either depend on Inferential Role Semantics (IRS) or are independently wrong. IRS: It’s part and parcel of dog meaning ‘dog’ that the inference from x is a dog to x is an animal is valid. lexical entries = ‘bundles of inferences’ IRS is wrong: It might be that what denotes a dog denotes an animal but knowing that dogs are animals is not necessarily for knowing what dog means.
a) Interlexical Semantic Relations P: An atomistic and purely denotational lexicon will fail to capture ‘interlexical relations’. For example: • a lexical entry that says only that dog refers to ‘dogs’ will not specify that dogs are animals (hyponymy). • a lexical entry that says only that bachelor refers to ‘bachelors’ will not thereby specify that bachelor means the same as unmarried man (synonymy). FL: Such a constraint (including ‘interlexical relations’) should not be imposed on lexical entries, because these relations are not part of the linguistic meaning.
‘Analytic inferences’ (lexical entailments) They are not meaning constitutive because even if necessary they are not part of what it means to know a word. e.g. dog animal, square circle ‘Defeasible inferences’ are not even necessary. - from want a cigarette to want to smoke a cigarette (Synonymy relations are typically defeasible.) - plank and board synonymous in some contexts - elephants and asteroids in the context are often bigger than a bread box -from my wife uses the subway every day to wife travels on the subway every day
Questions to be answered by any IRS theory. • What distinguishes lexical entailment form mere necessity? • What distinguishes linguistic knowledge from world knowledge? Important questions for deciding which of inferences (interlexical relations) are meaning constitutive and which are not.
b) Semantic Well-Formedness P: A level of representation in the semantics of words, which operates according to its own set of constraints. Examples of semantic ill-formedness? • ?Mary buttered the toast with butter. • ?John began the dictionary. • ??Mary began the rock. FL: Semantic well-formedness can’t be a constraint on representations of lexical meanings without determining first what it means for sentence to be semantically ill-formed.
c) Distribution P: Semantic determinants of syntactic contributions should be part of the lexical entries. FL: a) Semantics/syntax correlations have not been made out with sufficient clarity to permit the claims to be evaluated. e.g. John is running. Therefore, John has run. John is building a house. *Therefore, John has built a house. b) Even if syntax is semantically driven, it doesn’t necessarily count in favor of a semantics of lexical meanings ratherthan denotations.
d) Generativity J: The complexity of lexical entries is required to account for lexical generativity. The more context sensitive the meanings of governing expressions are supposed to be, the richer must be the lexical entries for the expressions they govern. FL: a) Polysemy is compatible with denotational semantics. If a word is ambiguous, then it denotes two different objects, processes etc. b) Polysemy doesn’t count in favor of the complexity of lexical entries. Because it is no evidence that the meaning of governing expressions is ever modulated by the semantics of the expressions that they govern. Examples: • Bake a cake vs. bake a potato (bake as ‘creative’ and as ‘warming up’) • Good knife vs. good car • Bank a check vs. bank a plane
- Generativity and lexical complexivity should be dissociated. With denotational semantics it is still an open question whether generativity should be accounted for. (Whether cake contributes to the meaning of bake a cake is neutral as to whether the lexicon is generative.) • What is the function of the dot operator if not to account for the data in a post hoc fashion? (The lexical entries are not constrained if they are allowed to combine freely.)
Pustejovsky against Fodor & Lepore Main criticism: FL fail to explain the semantic properties of natural language use. Silence over a number of observable phenomena that exhibit undeniable systematicity (e.g. object drop, phenomena, constraints on coercion etc.) In particular, they fail to account for: • logical relationships between the senses explaining what combinations are possible in natural language • the non arbitrary modes of inheritance for concepts associated with linguistic expressions FL do not recognize the relevance of polysemy to semantic theory. With words having fixed meanings the expressive and creative power of word sense cannot be accounted for.
2b) Analyticity P: FL’s criticisms of the representational hypothesis in natural language semantics crucially rely on the impossibility of a distinction between analytic and synthetic expressions: there is nothing in the form of the semantic representation associated with a word that can be inviolably as part of its meaning. Analyticity need not require the concepts of definition and substitution, as conventionally assumed. It does presuppose, however, a specific mode of identification in the computation of an expression. In the process of determining the interpretation of a sentence, we can identify subprocesses that are analytic in nature and those that are not. [Bake the cake is formally ambiguous just as John drank two wines can refer to portions or kinds. FL miss the point: co-composition is not an obligatory semantic rule.]
Its part of our analytic knowledge about verbs such as like and enjoy that allows syntactic variation. The distinction is not just a pragmatic one, revealing different conventions of usage for the two verbs, but arises from the underlyingly distinct types selected for by these verbs. a. Mary enjoys watching movies. b. Mary enjoys movies. a. Mary likes to watch movies. b. Mary likes watching movies. c. Mary likes movies. d. Mary likes for John to watch movies with her. e. Mary likes that john watches movies with her. f. Mary likes it that John watches movies with her.
Compositionality P: FL’s notion of compositionality (‘licencing an inference’) is irrelevant to the evaluation of semantic theories. To hold that ‘brown cows’ are dangerous, when neither brown nor cows contains hints of danger, is not devastating to the view that meanings are construed compositionally from word meanings; it is simply irrelevant. Not all inferences associated with the composition of the expressions have equal force. (The set of possible identifiable inferences associated with a particular expression should not be confused with those that are automatic and unsuprising to the expression.)