Next, the derivational process at LoC is mainly controlled by the need to
make the thematic roles assigned at LoT visible to hearers, which can be called
the Visibility Requirement.
(17) Visibility Requirement
Thematic roles of NP must be visible at the Communicative Interface.
The former Visibility Condition has been considered to be imposed at the
CI interface.^15 In the model presented here, however, SEM1 is visible intrinsi-
cally because it is a direct output from LoT and what matters is SEM2 at the
SM interface. In other words, as (18) shows, thematic roles at LoC are invisible
to hearers and several systems such as case infl ections, functional projections
and prosody help to make them visible.
(18) a. [√like √John In this paper we focus on morphological case and functional projections. (19) (19) Thematic roles and morphological cases In (20) functional projections help to make thematic roles visible. For example, (20) Thematic roles and FPs (21) indicates the change of the ways to keep the visibility in the history of the (21) morphological case > morphological case and FP > FP That is, as (22) illustrates, thematic roles were made visible by morphological case √like]]] → CI interface → SEM1
b. [√like √John<exp←necessary to identify> [√like √these socks<th←necessary to identify> √like]]]
→ SM interface → SEM2
is an example of the morphological case realization.^16
a. Agent is made visible by Nom.
b. Experiencer is made visible by Dat.
c. Recipient is made visible by Dat.
d. Theme is made visible by Nom or Acc.^17
F
a. Agent is made visible by F
b. Experiencer is made visible by F
c. Recipient is made visible by F
d. Theme is made visible by F.
e. Patient is made visible by F
f. Goal is made visible by F
English language.
in early English, whereas in PDE, FP plays a role in identifying them as in (23).
Two aspects of syntactic evolution 205