Advances in Biolinguistics - The Human Language Faculty and Its Biological Basis

it gets more deeply embedded into a larger SO. To extend this inductive
defi nition to formal features, let us assume that each LI can be characterized
as a set of features and that, therefore, any feature F of an LI H counts as a
daughter of H. Then, it follows that no feature F of H and XP can be equally
prominent in {H, XP}, because, given Depth(H) = Depth(XP), it is necessarily
the case that Depth(F of H) < Depth(F of some other LI H’ within XP).
Therefore, {H, XP} can never count as symmetric according to the defi nition
in (18).
In contrast, (9b) and (10b) can still successfully count as symmetric, given
the defi nition of structural prominence in (18). Furthermore, SOs created by
head-movement also count as symmetric. To take a familiar example, consider
a prototypical case of V-to-v head-movement in (19).

(19) a.
v[V]
V[uCat] nP

b.

a’. {v, {V, nP}} b’. (i) {v, {V, nP}}
(ii) {v, V}

V-to-v head-movement can be regarded as an instance of root-incorporation,
driven by the need to categorize the root (the same can be said of N-to-n and
A-to-a movement as well). We may describe this situation by assuming that
root categories are associated with an unvalued Cat(egorial)-feature that is in
need of matching with a neighboring categorizer. Then, root-incorporation
can also be seen as driven by the need for Cat-feature symmetry. (19) illustrates
the situation with V-to-v IM, where V/root’s [uCat] enters into a Cat-equi-
librium with v’s [V-Cat] (a categorial-feature valued as [V(erb)]). Further, if
we follow Chomsky (2007, 2008) and Richards (2007) in assuming that T’s
tense feature is dependent on C, then we might also say that T-to-C incorpora-
tion is just another instance of movement driven by the need for feature-
equilibrium. We assume that T has an unvalued T(ense)-feature [uT] that
undergoes matching with an interpretable counterpart in C. Thanks to this
T-feature-matching, T-to-C movement results in a symmetric structure {T, C},
just like root-incorporation.

(20) a.
C[vT]
T[uT] vP

b.

a’. {C, {T, vP}} b’. (i) {C, {T, vP}}

(ii) {C, T}

C

T

[vT]

[vT] vP

v[V]

V[V] nP

18 Hiroki Narita and Naoki Fukui