In ergative and active languages only secondary topicalization, by means of changing the word order in the sentence, is possible. Primary topicalization or subjectivization – choosing either agent or patient as subject – is not possible in these languages. This is due to the fact that in ergative languages transitive verbs lack the opposition of an active and passive voice and in active languages the version opposition is of a non-voice character.
Standardized
IF alignment is ergative or active, THEN primary and secondary topicalization cannot be by means of diathesis/voice alternations, but only by means of word order changes.
An absence of a voice opposition in ergative languages was also claimed by Serebrennikov (1974: 300), among many others.