欲しい and たい: Desire Grammar and Person Restrictions

Core examples: 水が欲しい, 行きたい, 彼は行きたがっている, 欲しがる, 食べたいです, 休みたいと言っています.

Desire is not reported equally for everyone

Japanese does not treat everyone’s desire as equally accessible. You can state your own wants directly:

水が欲しい。 I want water.

日本へ行きたい。 I want to go to Japan.

But when talking about someone else’s desire, Japanese often requires observation, report, or evidential marking:

彼は水を欲しがっている。 He wants water / He is showing signs of wanting water.

彼は日本へ行きたいと言っています。 He says he wants to go to Japan.

The key principle is:

Japanese desire grammar distinguishes direct inner access from observed or reported desire.

This affects 欲しい, たい, 欲しがる, たがる, and quoted speech.

欲しい: wanting a thing

欲しい expresses wanting a noun.

Examples:

水が欲しい。 I want water.

新しいパソコンが欲しいです。 I want a new computer.

The desired object is often marked with が.

In polite form:

コーヒーが欲しいです。

This is grammatical, but in many service situations it can sound too direct or childish compared with:

コーヒーをお願いします。 Coffee, please.

コーヒーをいただけますか。 Could I have coffee?

Desire grammar is not the same as request grammar.

たい: wanting to do an action

たい attaches to the masu stem of a verb:

行く → 行きたい want to go

食べる → 食べたい want to eat

休む → 休みたい want to rest

Examples:

寿司を食べたいです。 I want to eat sushi.

今日は早く帰りたい。 I want to go home early today.

The object can be marked with を or が depending on construction and nuance:

寿司を食べたい。 I want to eat sushi.

寿司が食べたい。 Sushi is what I want to eat.

Both are common. が often highlights the desired object.

Third person: たがる and 欲しがる

For third-person observable desire, Japanese often uses がる forms:

彼は行きたがっている。 He wants to go / is acting like he wants to go.

子どもがお菓子を欲しがっている。 The child wants sweets / is asking for sweets.

たがる and 欲しがる frame desire as observed from outside. You see behavior, hear complaints, or infer from actions.

Reporting desire with と言う

If someone states their desire, use quotation/reporting:

彼は休みたいと言っています。 He says he wants to rest.

田中さんは新しい車が欲しいそうです。 I hear Tanaka wants a new car.

This avoids pretending direct access to their mind. You are reporting a source.

Fiction and inner access

In fiction, narration may describe a character’s inner state more directly because the narrator has access.

彼は帰りたかった。 He wanted to go home.

This is natural in narrative writing. The person restriction is not a mechanical ban. It depends on viewpoint, evidence, and genre.

Desire versus request

Wanting and asking are different.

Direct desire:

水が欲しいです。 I want water.

Request:

水をください。 Please give me water.

Polite request:

お水をいただけますか。 Could I have water?

In Japanese, stating desire may be less appropriate than making a conventional request, depending on relationship and setting.

Desire-expression checklist

When expressing desire:

1. Whose desire is it?
2. Noun or action? 欲しい for thing, たい for action.
3. Direct access? Can the speaker know this directly?
4. Observation? Use がる forms.
5. Report? Use と言う, そうだ, らしい.
6. Request context? Use ください, お願いします, いただけますか.
7. Register? Casual, polite, formal, service?
8. Object marking? が for desired object focus, を for action object.

Reporting other people’s desire without mind-reading

Japanese is careful about direct access to inner states. This does not mean you can never talk about what someone wants. It means you choose grammar that shows how you know.

For yourself, direct forms are natural:

水が欲しいです。 I want water.

日本へ行きたいです。 I want to go to Japan.

For asking the listener, questions are natural because the listener can answer:

何が欲しいですか。 What do you want?

どこへ行きたいですか。 Where do you want to go?

For third persons, use observation, report, or quotation:

子どもが水を欲しがっています。 The child wants water / is showing desire for water.

田中さんは日本へ行きたいと言っています。 Tanaka says he wants to go to Japan.

田中さんは日本へ行きたそうです。 Tanaka looks like he wants to go to Japan.

The distinction is not grammatical fussiness. It protects the speaker from claiming direct access to another person’s mind.

A practical scale:

Learners often overuse たい for third persons because English allows “he wants to...” freely. Japanese asks you to mark whether you saw it, heard it, inferred it, or are quoting it.

A strong tool for this article would separate person and evidence.

Suggested functions:

1. Person selector: first, second, third.
2. Desire type: noun 欲しい vs verb たい.
3. Evidence mode: direct, observed, reported, fictional narration.
4. Request converter: 水が欲しい → 水をください → お水をいただけますか.
5. Object marker practice: 寿司を/が食べたい.
6. Register warnings for service, workplace, and casual use.

Final rule

Japanese desire grammar asks whose mind you can access.

Use 欲しい and たい freely for your own desires. Use questions carefully for the listener. For third-person desire, mark observation or report with がる, と言う, そうだ, or らしい unless the narrative viewpoint allows direct access.

Wanting is grammar. Evidence is grammar too.