The syntactic restriction on the passive in Southern Tiwa is that it cannot be formed if the subject of the sentence is not represented by a noun. For example, the sentence I saw the man cannot be changed into a passive construction The man was seen by me, as the latter will be ungrammatical. This takes place because in Southern Tiwa the categories of person and number are expressed by affixes which are added to verbs. According to Tallerman there are two “properties” of passive which are similar in many languages: it presupposes promotion of the object and demotion of the subject (21). Basically, no pronouns are used: the phrase You saw me in English (the subject and the object are expressed by pronouns) is expressed by a verb with corresponding affixes in Southern Tiwa. These affixes represent both the subject and the object, so the object (expressed by an affix) cannot be put into the demoted position as an affixe cannot become a separate part of a sentence.
Apparently, if the subject and the object are not expressed by nouns, the subject and the object are expressed by affixes added to the verb in Southern Tiwa. The form of the verb signals about the doer of the action, and the object of this action. Therefore, the object cannot be in passive position as in cases of (4), (6), (10) it is expressed by affixes. So, it is ungrammatical to say by me or by you in Southern Tiwa. This is why examples in (4), (6) and (10) are ungrammatical.
The Southern Tiwa has certain restrictions on the passive. This can be due to peculiarity of the verb in this language. The verbs have affixes which denote the person (doer of the action and the object of the action). Logically, there are not all pronouns which exist in other languages as they appear to be superfluous (as the verb possesses the necessary aspects of person and number). Thus, it becomes impossible (or rather ungrammatical) to form the passive structures in sentences where the subjects and the objects are not expressed by nouns. Therefore, the object expressed by pronouns cannot be put in the demoted position.
Work Cited
Tallerman, Maggie. Understanding Syntax (Second Edition). Oxford: University Press, 2005.