A は／が difference


> **Possible Duplicate:**  
>  [What’s the difference between wa (は) and ga
> (が)?](https://japanese.stackexchange.com/questions/22/whats-the-difference-
> between-wa-%e3%81%af-and-ga-%e3%81%8c)

I've been trying to wrap my head around the は/が differences, and I'm trying to
figure out the differences between the thematic は and the neutral descriptive
が.

Take for example.

> 日本語の授業は面白いです。

vs

> 日本語の授業が面白いです。

Can someone tell me the difference between the switching of the particles?




The key to understanding は is to understand how a sentence ties back to the
discourse. This is where the "topic" comes in. Some linguists will claim that
all Japanese sentences have a topic, even if it's implicit and unstated.

If you're asked:

> 日本語の授業についてどう思いますか？  
>  What do you think about your Japanese lessons?

what ties back to the discourse is "日本語の授業", so it will be marked with は:

> 日本語の授業は面白いです

On the other hand, if somebody says to you:

> 今日は機嫌がいいですね  
>  You're in a good mood today

what ties back to the discourse is _not_ "日本語の授業", rather, it's the cause-and-
effect relationship of why you're in a good mood. Using the sentence with は
will sound strange, as if you're switching topics. Rather, to explain why
you're in a good mood (staying on topic, although the topic is never
explicitly stated), you might say:

> 日本語の授業が面白いです

Note that this (has a reading which) is _not_ an exhaustive-listing が. **I
disagree with the answers that claim that there's no "neutral description" が
for this sentence because 面白い is not state-change.**

Just to preempt possible comments, this sentence does sounds slightly
uncommon. Usually it is more idiomatic to add a の/ん, which is another way to
tie a sentence into a discourse.

> はい、日本語の授業が面白いんです  
>  Yes, my Japanese classes are fun!

So to your question in the comments about whether this が is exhaustive-listing
or neutral-description, my answer is: "It can be both".

