The differences between “が” and “は”.

I’ve been teaching quite a few students online. I saw some students struggle to understand how to use “が” and “は” and the differences in between those two. In this article, I would like to explain more clearly.

You need to consider 5 cases when you accurately use が and は.

1. If it’s a new information or not.
2. If it’s a sentence to indicate phenomenon or judgement.
3. If it’s the nominative case for whole sentence or for only some parts of sentence.
4. If it means comparison or exclusion.
5. If the nominative case can be replaced to the objective case or not.

Here are the explanation to prove those logic with some examples below.

1. If it’s a new information or not.

が is used for unknown things but は is used for known things.

Ex.

A : かれが　社長しゃちょうです。

A : He is a president. (A speaks to someone who doesn’t know he is a president.)

B : かれは　社長しゃちょうです。

B : He is a president. (B speaks to someone who knows he is a president.)

2. If it’s a sentence to indicate phenomenon or judgement.

が is used for the sentences without subjective judgement but は is used the ones including subjective judgement.

Ex.

A : 冷蔵庫れいぞうこに　りんごが　あります。

There is an apple in the fridge. (A just refers to the matter there is an apple in the fridge.)

B : 冷蔵庫れいぞうこに　りんごは　あります。（でも、　たまごはありません。）

There is an apple in the fridge. (B mentions there is an apple in the fridge but there might not be other foods.)

3. If it’s the nominative case for whole sentence or for only some parts of sentence.

If the nominative case is the subject of whole sentence, は is used.

If the nominative case is the subject of some parts of the sentence, が is used.

Ex.

A : わたしは　ねるとき、　必かならず　窓まどを　閉しめる。

When I go to bed, I definitely close the windows. (The subject is わたし.)

B : わたしが　ねるとき、　猫ねこが　いつも　近ちかくに来くる。

When I go to bed, my cat always comes closely. (The subject of the first part is わたし. Whereas, the one of the second part is 猫.)

4. If it indicates comparison or exclusion.

は is used to indicate comparison. が is used to indicate exclusion.

Ex.

A : わたしは　東京に　住んでいるけど、　かれは　大阪に　住んでいます。

I’m living in Tokyo but he is living in Osaka. (は is used to compare where I live and where he lives.)

B : わたしが　大阪に　住んでいます。

I’m living in Osaka. (This sounds like “I’m the only one living in Osaka. No one is living there except for me.”)

5. If the nominative case can be replaced to the objective case or not.

If the nominative case in a sentence can be replaced with the objective case, both は and が can be used. Whereas, if the objective case indicates the character of the subject, は is only used and the nominative case can’t be replaced with the objective case.

Ex.

A : 水は　液体です。

Water is liquid. (Liquid is the character of water. Therefore, は can’t be replaced が.)

B : わたしの名前は　田中です。

My name is Tanaka. (My name is equivalent to Tanaka. は can’t be replaced with が. Whereas, Japanese use は for their introduction.)