5 Head Movement

Head movement is the case of Move-α where the value of α is X°. As a case of Move-α, standard conditions on movement apply to it. These include locality, structure preservation, and the requirement that movement leave a well-formed trace. The principal locality condition on head movement is the Head Movement Constraint (HMC), originally proposed by Travis (1984) and given informally in (1): (1) Head movement of X to Y cannot " skip " an intervening head Z. In section 4 I discuss the theoretical status of (1) in detail. Its empirical consequences will be illustrated in sections 1, 2, and 3. The structure preservation requirement on head movement has the consequence that the landing site of head movement must always be another head. 1 Typically (notably in Baker 1988), head movement is taken to be adjunction of the moved head X° to the target head Y°; Kayne (1991, 1994) proposes that this must always be left-adjunction. Finally, head movement must leave a well-formed trace. Since a major well-formedness condition on traces is that they must be c-commanded by their antecedents, this forces head movement always to take place in an upward direction, where " upward " is understood as defined by c-command (some possible exceptions to this idea will be briefly discussed in section 2). Taking these conditions together, we arrive at the following general schema for head movement of X° to Y°: