“more superficial,”rather than simply“underlying” and“superficial,”is that derivational rules can chain up, one
applying to the output of another. Let me illustrate. In approaches that make use of derivational rules (i.e. all of
Chomsky's successive frameworks), it is standard to treat the subject of a passive sentence as derived from a more
underlying object, as sketched in (II). (I give only the string of words; the structure is to be understood.)
Similarly, it is standard to derive the subject of certain predicates such asseemfro ma more underlying subject of a
subordinate clause; that is, the underlying for mof (12b) is close to the nearly synony mous (12a). The derivational rule
involved is called“raising.”
(13) can then be derived as the product of passive followed by raising.
Inother words, we can understandthis bookas theunderlying objectofstudy, despiteits considerabledistancefro mthis
position. It has achieved this distance by a sequence of independently motivated movements.
Thus a full derivation for a sentence consists of the creation of an underlying form by means of the formation rules,
followed by a sequence of derivational rules to create the ultimate surface form.^21 In theAspects framework the
underlying for mwas called the sentence's“Deep Structure,”the most superficial for mits“Surface Structure”; in later
frameworks these terms were abbreviated to“D-structure”and“S-structure.”
Such a derivation has an inherent directionality, fro munderlying to surface. Students are always re minded that the
notion of movement is intended“metaphorically,”and that this directionality is just a way of defining a set of well-
formed structures. No claim is impliedthat speakers actuallymove phrases around intheir heads—thisis takentobea
matter of performance. However,
COMBINATORIALITY 47
(^21) In some approaches, such as thatof Syntactic Structures, the Minimalist Program, and Tree-Adjoining Grammar (Joshi 1987; Kroch 1987; Frank and Kroch 1995) ,
structures created by derivational rules can be inserted for variables in formation rules, so that this strict ordering need not be observed.