Topic drop and pro drop

One major difference between Chinese-type and German-type languages is that the former allows extensive types of argument drop, while the latter is quite limited beyond the existence of a null topic. This study argues (a) that it is necessary to distinguish among phenomena that have sometimes been referred to with the undifferentiating term “radical pro drop”; (b) that the null topic is restricted to root clauses (CP edge) based on its locality properties; (c) that the Chinese-type null topic requires licensing at the CP edge by Internal Merge; and (d) that the CP edge requirement may be lifted only under conditions of last resort. Evidence comes from our new observation of locality effects showing a contrast between overt and null topics. Specifically, while the pro option is available with an overt topic, null topics must be brought to the CP edge via Internal Merge.