A Cross Linguistic Analysis of Pro-drop Parameter in Persian

The Null Subject Parameter (NSP) can be defined based on ‘Subject Requirement Constraint’ of Perlmutter (1971) (Jaeggli & Safir 1989). According to this parameter, Null Subject Languages may have phonologically null subjects in tensed sentences whereas non-Null Subject Languages require phonologically realized subjects. Then all languages of the world can be divided to two subgroups: pro-drop or null subject languages and non-null subject languages. However in this article we want to show in spite of some similarities, the null subject languages have different properties and they are divided to four subgroups: consistent, expletive, discourse and partial null subject languages. This article deals with common properties of each subgroup and investigates justifying each of them based on null subject parameters of Rizzi (1982). It also studies the behavior of Persian and tries to find the status of Persian in such classification. This issue is critical especially when linguists want to investigate a syntactic phenomenon in Persian and try to achieve a generalization in this area.