of NP 4 or outside of S 3. This observation might be expressed as the“Head Constraint.”
(53) Head Constraint
The syntactic arguments and adjuncts in a phrase express the semantic arguments and modifiers of the
phrase's head.The Head Constraint is subject to various sorts of exception. First, an NP argument can be embedded in a PP whose
head is a governed preposition (a socalled oblique complement).Samandthe picture of Bethin (53) are probably such
arguments. Second, there are some situations in which the syntactic arguments in a clause are not arguments of any
verb at all; we defer discussion of this case, seldo mrecognized in the literature, to section 6.6.
However, the most important exceptions to the Head Constraint are cases where syntactic arguments of a verb are
found in positionshigherthan the verb's subject position. These situations have been a major focus in generative
grammar throughout its history, phenomena that every theory has to contend with. They are by now quite well
understood and well differentiated fro meach other, both in English and in crosslinguistic context.
Consider (54), which we encountered in section 3.2.2:Johnis a semantic argument oflikebut is not its subject.
(54) John seems [to like ice cream].Classicalgenerative grammar maintained theHead Constraintas a universalbysaying that it appliesinDeep Structure.
Recall the discussion in section 3.2.2:Johnis regarded as being the subject oflikein underlying form, in conformity
withtheHead Constraint;and in thecourse of thederivationit is raised to becomethesubject ofseem. In other words,
theapparent violationoftheHead Constraint is produced bya derivationalrule(“Raising”) that moves a phrase out of
the environment in which it initially serves as an argument. This keeps the semantics-to-underlying syntax interface
simplewithrespecttoargumentstructure,preservingthenotionthatunderlyingsyntacticstructureisrelativelycloseto
meaning.
Other generativeapproaches, notably LFG and HPSG, take a differenttack on thesort ofsyntax–semantics mismatch
illustrated in (54). These approaches are committed to the elimination of movement rules from the grammar; the
syntactic formation rules create a surface form directly. The greater simplicity in the syntactic component is
counterbalanced by a more complex syntax–semantics interface, one that treats the Head Constraint as only a default.
In particular, in configurations like (54) where the classical theory uses a derivational rule to move a constituent
upward, the non-derivational theories have an interface