ている in continuous or perfect aspects

Question

I learned that ている can be used in both Continuous Tense and Perfect Tense, and with both instant state change verbs and durative verbs. If we consider only durative verbs (e.g. 食べる, 作る etc.)

When is ている interpreted as Perfect Tense, and when does it mean Continuous Tense? Let us say, my mom asks me, お祖母さんが食べたか？ If I answer お祖母さんが食べています it can mean, both "My grandmother has eaten the food", and "My grandmother is eating the food". However, what I want to imply by using ている is that she has eaten the food i.e. to use the perfect tense.

A different example:

Yamada-san: あなたは何個のクッキーを作っていますか？

Sakura-san: 私は20個のクッキーを作っています

ている seems to mean either continuous or perfect tense, and the English translation provided by the dialogue creator is perfect i.e. "I have made 20 cookies."

1. When should ている with durative/action verbs be taken as perfect tense and when as a continuous tense? Could you please give me some practical examples and tips that I could use to differentiate?

2. Do native Japanese speakers usually interpret ている with action/durative verbs like 食べる, 作る, in perfect tense or as continuous?

3. Two adverbs まだ and もう also seem to be used in perfect aspect. もう leans towards a positive perfect tense reading, when used with a verb in the past tense (た）e.g. もう食べた (I have eaten), and まだ usually points to negative perfect tense with ていません e.g. まだ食べていません (I have not eaten). Also ~ことがある. So, my third question is, whether the one of/sole purpose of using adverbs もう and まだ, is to remove the conflict, and confusion, arising because of durative/action verbs having two tenses when using ている? E.g. does the use of もう食べた, instead of plain 食べています (which also has the same perfect meaning) to remove the confusion, when the person wants to tell his state that he has eaten the food?

Answer 1

You have asked a very similar question before: Usage of ている in Punctual Verbs in Japanese and the Concept of Present Perfect in English

Ultimately, this is something you have to gradually get used to. In English, must as in "You must be hungry" and must as in "You must be brave" have different meanings, and you can somehow distinguish them intuitively. Is there a grammar rule we can use to tell apart the two meanings? No. It depends on the context and "common sense" so heavily that we cannot write rules about it. Likewise, English perfect aspect has several meanings, which has confused me for more than 20 years, seriously. I think you have already taken enough time to learn the basics of the teiru-form. From here, rather than asking "tell me everything about this form" sort of questions, you are better off learning and mastering the form through many examples.

As for 何個のクッキーを作っていますか, indeed it can mean both "How many cookies are you making (now)?" and "How many cookies have you made?", depending on the situation. Both interpretations are perfectly natural, and it's almost nonsense to ask for the "default". However, this sentence is unlikely to be confusing in practice; who says this without knowing whether the listener is making cookies now? If this sentence appears in a textbook in isolation, no one can tell which reading is intended. Simply, grammar is useless in such a situation.

Here are some hints which are useful in some cases:

• There are some verbs that exclusively accept perfective readings. Well-known ones include 知る, 始まる, 終わる, 死ぬ and 結婚する. The teiru-forms of these verbs always refer to instant changes of state, and there is no intermediate point.

  ^{(Although uncommon, the teiku-form can still express progression of these verbs. 蝶が死んでいくのを見ていた = "I was watching a butterfly dying over time." 夏が終わっていく = "Summer is (gradually) going away.")}

• The teiru-forms of the vast majority of verbs accept both perfective and progressive readings with varying degrees of frequencies. That punctual/durative classification is useful, but it's not an ironclad rule.

• There are many verbs whose teiru-form are almost always perfective but still can be forced to accept progressive readings in combination with ～ところ. (It's explained in this answer.)

  花瓶が割れているところを撮ったスローモーション映像
  a slow-motion footage of a vase being broken

  (Note that 今, 現在 and so on do not force progressive reading. 現在結婚しています means this person married in the past and still in the married status now.)

• You can force perfective readings using several keywords including これまでに, 過去に and ～回.

  彼はこれまでに3回寿司を食べています。
  He has eaten sushi for three times.

  (Note that もう does not force perfective readings. It just means "already". 彼はもう走っている can mean "He is already running" as well as "He has already run".)

Again, these rules are mostly useless for your 作っています example. Unfortunately, many verbs are like this. All you can rely on is the context and the judgment you can gradually gain through many examples.

Answer 2

So, my first question is, when is ている in durative/action verbs is to be taken as perfect tense and when as a continuous tense? Could you please give me some practical examples and tips that I could use to differentiate?

There are 動作動詞・継続動詞 (verbs of action, verbs of continuation) and their ~ている-form means it's a 進行中 (progressive action), like 食べている. Someone is still in the process of eating.

There are 瞬間動詞・変化動詞 (verbs of change) and their ~ている-form means it's a 結果残存.

More examples for 瞬間動詞・変化動詞 (verbs of change): 電気が付く 人が死ぬ 二人が結婚する

These 瞬間動詞 (verbs of change) ends instantly, take the first 電気が付く as an example: 電気が付く is a 瞬間動詞, therefore 電気が付いている expresses "the light is on", a state.

So, my second question is, do Japanese speakers, especially natives, usually interpret ている in action/durative verbs like 食べる, 作る, in perfect tense or as continuous?

Already answered above. And seems that if you want express 食べている as "already eaten", もう or すでに is preferred to add, or you have the texts to inform that it means already eaten.

So, my third question is, whether the one of/sole purpose of using adverbs もう and まだ, is to remove the conflict, and confusion, arising because of durative/action verbs having two tenses when using ている? E.g. does the use of もう食べた, instead of plain 食べています (which also has the same perfect meaning) to remove the confusion, when the person wants to tell his state that he has eaten the food?

I have to correct your mistake, もう in fact expressed there's something already changed, and まだ expressed there's nonthing changed.

Therefore:

もう食べた。 Already eaten.

もう食べている。(Like we don't usually say this)

もう食べていない。No longer eat anymore


まだ食べた。(Makes no sense)

まだ食べている。Be still eating

まだ食べていない。Be still NOT eating