Editing Japanese grammar (section)

===Japanese as a topic-prominent language===
In [[discourse]] [[pragmatics]], the term ''topic'' refers to what a section of discourse is about. At the beginning of a section of discourse, the topic is usually unknown, in which case it is usually necessary to explicitly mention it. As the discourse carries on, the topic need not be the grammatical subject of each new sentence.

Starting with [[Early Middle Japanese|Middle Japanese]], the grammar evolved so as to explicitly distinguish topics from nontopics. This is done by two distinct [[Japanese particles|particles]] (short words which do not change form). Consider the following pair of sentences:

{{fs interlinear|indent=3|lang=ja|transl=Hepburn|glossing=no abbr
|犬 '''が''' サンド を 食べている。
|inu '''ga''' sando o tabeteiru
|dog NONTOPIC sandwich OBJ eat|}}

{{fs interlinear|indent=3|lang=ja|transl=Hepburn|glossing=no abbr
|犬 '''は''' サンド を 食べている。
|inu '''wa''' sando o tabeteiru
|dog TOPIC sandwich OBJ eat|}}

In the first sentence {{nihongo|the dog|犬|inu}} is not a discourse topic—not yet; in the second sentence it is a discourse topic. In linguistics (specifically, in discourse pragmatics) a sentence such as the second one (with {{transliteration|ja|wa}}) is termed a '''presentational''' sentence because its function in the discourse is to present ''dog'' as a topic, to "broach it for discussion". Once a [[referent]] has been established as the topic of the current monolog or dialog, then in (formal) modern Japanese its marking will change from {{transliteration|ja|ga}} to {{transliteration|ja|wa}}.

To better explain the difference, the first sentence can be translated to "There's a dog eating a sandwich", while the second sentence can be translated to "You know the dog? It's eating a sandwich"; these renderings reflect a discourse fragment in which "the dog" is being established as the topic of an extended discussion. The first sentence answers the question "What is going on?," whereas the second sentence answers the question "What is the dog doing?"