Notes on labeling and subject positions

The study of subject positions has illuminated different aspects of syntactic theory as well as the study of the interface with meaning and discourse. For instance, the analysis of the constraints on subject movement has nourished much research on locality, leading to various versions of the Empty Category Principle (Chomsky 1981) and to the subsequent study of freezing effects; and then the discovery that “free subject inversion ” in Romance is in fact local movement of the thematic subject to a low focus position (Belletti 2001, 2004) has profoundly modified the study of the Null Subject Parameter (with consequences for the general conception of the parametric approach), and has contributed to establish the transparent view of the syntax – pragmatics interface which is congenial to cartographic studies. In this paper I would like to address some properties of subjects which interact in significant ways with a key ingredient of syntactic computations: the algorithm that assigns labels to the structures created by merge. I will first adopt a version of the approach proposed in Chomsky (2013), according to which the assignment of labels is essentially a matter of locality. The functioning of the system will be illustrated on the basis of the implementation proposed in Rizzi (2013), in connection with the fact that subjects typically must undergo movement and vacate the thematic position. This raises a “halting problem ” for subject movement: under what conditions can it stop? Where does it have to stop, giving rise to a freezing configuration? Can freezin