Within
generative grammar, various types of movement have been distinguished. An important distinction is the one between head movement and phrasal movement, with the latter type being further subdivided into A-movement and A-bar movement. Copy movement is another more general type of movement.
A-movement vs. A-bar movement Argument movement (A-movement) displaces a phrase into a position in which a fixed grammatical function is assigned, such as in movement of the object to the subject position in passives: ::a. Fred read
the book. ::b.
The book was read ___ (by Fred). - A-movement Non-argument movement (A-bar movement or A'-movement), in contrast, displaces a phrase into a position where a fixed grammatical function is not assigned, such as the movement of a subject or object NP to a pre-verbal position in interrogatives: ::a. You think
Fred loves Mary. ::b.
Who do you think ___ loves Mary? - A-bar movement ::a. You think Fred loves
Mary. ::b.
Whom do you think Fred loves ___? - A-bar movement The A- vs. A-bar distinction is a reference to the theoretical status of syntax with respect to the lexicon. The distinction elevates the role of syntax by locating the theory of voice (active vs. passive) almost entirely in syntax (as opposed to in the lexicon). A theory of syntax that locates the active-passive distinction in the lexicon (the passive is not derived via transformations from the active) rejects the distinction entirely.
Phrasal movement vs. head movement A different partition among types of movement is phrasal vs. head movement. Phrasal movement occurs when the
head of a phrase moves together with all its dependents in such a manner that the entire
phrase moves. Most of the examples above involve phrasal movement. Head movement, in contrast, occurs when just the head of a phrase moves, and the head leaves behind its dependents. Subject-auxiliary inversion is a canonical instance of head movement: ::a. Someone
has read the article. ::b.
Has someone ___ read the article? - Head movement of the auxiliary verb
has ::a. She
will read the second article. ::b.
Will she ___ read the second article? - Head movement of the auxiliary verb
will On the assumption that the auxiliaries
has and
will are the heads of phrases, such as of IPs (
inflection phrases), the b-sentences are the result of head movement, and the auxiliary verbs
has and
will move leftward without taking with them the rest of the phrase that they head. The distinction between phrasal movement and head movement relies crucially on the assumption that movement is occurring leftward. An analysis of
subject-auxiliary inversion that acknowledges rightward movement can dispense with head movement entirely: ::a.
Someone has read the article. ::b. ___ Has
someone read the article? - Phrasal movement of the subject pronoun
someone ::a.
She will read the second article. ::b. ___ Will
she read the second article? - Phrasal movement of the subject pronoun
she The analysis shown in those sentences views the subject pronouns
someone and
she as moving rightward, instead of the auxiliary verbs moving leftward. Since the pronouns lack dependents (they alone qualify as complete phrases), there would be no reason to assume head movement. ==Islands and barriers to movement==