Interchangeability of Ablative and Instrumental Cases in Avestan Language

In Avestan Language, ablative case is sometimes used for encoding functions of instrumental case and instrumental case is used for encoding functions of ablative case. These two cases encode semantic roles. Ablative case is a spatial case whose main function is to encode source, location, and path. Instrumental case is a non-spatial case whose main function is to encode accompaniment, instrument, manner as well as cause and agent in passive voice. Ablative and instrumental cases- in case hierarchy- are located in the last position and are not distinguished hierarchically. In the present study, Avestan data were explored and it was found that these two cases are polysemic and overlap functionally; hence, they are used interchangeably in Avestan language. The ablative case encodes the semantic roles of manner and cause in passive voice in addition to semantic roles of source, location, and path. Along the same vein, the instrumental case indicates source, path and location in addition to semantic roles of accompaniment, instrument, manner and cause and agent in passive voice. Semantic map of these two cases is drawn to demonstrate their semantic range and polysemy.