if both are used to clear the topic of a sentence and what is spoken about, who do i know wich one to use?
difference between "wa" and "ga"

MensoW
October 27, 2020

EarleyGrave
October 28, 2020
WA/は is a topic marker and GA/が is the subject marker. Each sentence has a subject/GA, though they are usually understood through context and dropped from the sentence. As for a topic/WA, you can translate that part as “As for X…” or “In regards to X…”.
“Watashi-WA Amerika-Jin Desu” is actually “As for me, (I) am an American".
The pronoun “I” isn't Watashi-WA… it's an implied Watashi-GA. If you said “Amerika-Jin Desu”, it would still be understood as “I'm an American” with the same implied GA. [This GA is expected to be dropped, so if you say “Watashi-GA Amerika-Jin Desu”, it heavily emphasizes the “I”.]
The topic and the subject can be different. If you overhear someone saying “Watashi-WA Usagi Desu”, you might think they're saying “As for me, (I) am a rabbit”. More likely they are responding to a question, like what they'd like to eat, with “As for me, (it) is rabbit”. The “it” is the omitted subject that people understand through context.
If you use both WA & GA in the same sentence, the WA will come first. “Watashi-WA Neko-GA Suki Desu” gets translated to “I like cats”, but it's closer to meaning “to me, cats are pleasing”. The cats are the actual subject. What makes sentences like this confusing is that in our typical English translation, we turn the adjective “suki” into the verb “like”! The more we understand Japanese in Japanese, the less confused we become. ;)
There are more nuances, and I'm by no means a master of the language, so I'd recommend you check out a YouTube video series called “Organic Japanese with Cure Dolly”. It goes over WA/GA pretty extensively, even within the first 2-3 videos.
Cheers!

Emma-Rocket-Japanese-Tutor
October 29, 2020
Thanks for your question! は (Wa) and が (ga) are definitely one of the most complicated concepts to grasp in Japanese.
Here's a quick summary:
- は (Wa) is used to identify the TOPIC (or theme) of a sentence. It is mainly used with nouns and adjectives; however, you can also use it with verb when you want to show CONTRAST.
- が (Ga) is the IDENTIFIER particle, since it can identify a whole bunch of things, for example, the SUBJECT of a sentence. Since the subject is a person or thing that does an action, we usually use が (ga) with verbs, but we can also use it with nouns and adjectives when we really want to EMPHASIZE something.
In most sentences, you can use は (wa) or が (ga) interchangeably, it really just depends on what you want to say.
In EarleyGrave's example, "I am American," we could in fact ay this in one of two ways:
わたし は アメリカ じん です。 (Watashi wa Amerika-jin desu)
わたし が アメリカ じん です。 (Watashi ga Amerika-jin desu).
Both of these sentences are perfectly correct! However, when we use が here, we're really pointing out that the one who is American is "I" (and not someone else). I've bolded which part of the sentence is the most important to make it a little clearer.
Also, EarleyGrave, just like you say, when the subject or topic of the sentence is obvious from context, we usually leave it out.
If you want to learn a little more about how these particles work, you can check out our brand new Language and Culture lessons on は (wa) and が (ga) from the links below:
は (Wa)
https://members.rocketlanguages.com/members/japanese/lessons/5040/1-7-Introducing-Yourself
が (Ga)
https://members.rocketlanguages.com/members/japanese/lessons/5041/1-8-To-Like-Not-Like
https://members.rocketlanguages.com/members/japanese/lessons/5042/1-9-Describing-Things
I hope this helped! Please let me know if you have any more questions.
べんきょう を がんばって ください! (Benkyō o ganbatte kudasai!)

EarleyGrave
October 29, 2020
Thanks Emma, I'm not very good at explaining this stuff. It's good we have new lessons too!