Mastering “~でしょう”: Your Definitive Guide to Expressing Conjecture and Seeking Confirmation in Japanese

~でしょう (~deshou)

Are you studying for the JLPT and sometimes feel like you’re drowning in a sea of Japanese nuances? Do phrases like “I think,” “probably,” and “isn’t it?” seem to have a dozen different ways to say them, each with its own subtle twist? If you’ve ever found yourself scratching your head over how to express probability or gently ask for confirmation without sounding too blunt, you’re absolutely not alone.

Many Japanese learners, especially those aiming for the JLPT N4 or N3 levels and beyond, struggle with the versatile yet tricky grammar point: ~でしょう (~deshou). It’s one of those expressions that seems simple on the surface but carries a surprising amount of depth and flexibility, reflecting the speaker’s confidence, politeness, and intention.

But fear not! By the end of this comprehensive guide, you’ll not only understand the fundamental rules of ~でしょう but also grasp its various nuances, learn how to use it confidently in everyday conversations, and avoid common pitfalls that trip up even intermediate learners. We’ll break down its structure, explore its multiple applications with practical examples, and compare it with similar expressions to give you a crystal-clear understanding. Get ready to elevate your Japanese communication skills!

The Core of “~でしょう”: Unpacking Its Basic Structure

At its heart, ~でしょう is an auxiliary verb (助動詞, jodōshi) that attaches to various word types. It’s the polite form of ~だろう (~darou), which is its plain or informal counterpart. Both essentially convey a sense of conjecture, probability, or a softened question.

Understanding the Conjugation Rules

Connecting ~でしょう to different parts of speech is straightforward once you know the pattern. Here’s how it works:

1. With Verbs: Use the Plain Form (Dictionary Form, Past Form, Negative Form)

When attaching ~でしょう to verbs, you typically use their plain forms. This includes the dictionary form (辞書形, jishokei), plain past form (た形, ta-kei), and plain negative forms (ない形, nai-kei).

• Present Affirmative: 食べる (taberu, to eat) + でしょう → 食べるでしょう (taberu deshou)
• Present Negative: 食べない (tabenai, not to eat) + でしょう → 食べないでしょう (tabenai deshou)
• Past Affirmative: 食べた (tabeta, ate) + でしょう → 食べたでしょう (tabeta deshou)
• Past Negative: 食べなかった (tabenakatta, didn’t eat) + でしょう → 食べなかったでしょう (tabenakatta deshou)

A quick note on polite verb forms: While technically possible to attach ~でしょう to the ます-form (e.g., 食べますでしょう), it’s far less common and can sometimes sound a bit stiff or redundant. In most cases, using the plain verb form with ~でしょう is polite enough for expressing conjecture or gentle questions. For direct polite invitations, you would use ~ましょう (~mashou, e.g., 食べましょう).

2. With い-Adjectives: Attach Directly

For い-adjectives, simply attach ~でしょう directly to the adjective itself.

• Present Affirmative: 暑い (atsui, hot) + でしょう → 暑いでしょう (atsui deshou)
• Present Negative: 暑くない (atsukunai, not hot) + でしょう → 暑くないでしょう (atsukunai deshou)
• Past Affirmative: 暑かった (atsukatta, was hot) + でしょう → 暑かったでしょう (atsukatta deshou)
• Past Negative: 暑くなかった (atsukunakatta, wasn’t hot) + でしょう → 暑くなかったでしょう (atsukunakatta deshou)

3. With な-Adjectives and Nouns: Add 「で」 Before ~でしょう

This is where it gets slightly different. For な-adjectives and nouns, you need to insert 「で」 (de) before ~でしょう.

• な-Adjective (Present Affirmative): 静か (shizuka, quiet) + でしょう → 静かでしょう (shizuka deshou)
• な-Adjective (Present Negative): 静かじゃない (shizuka janai, not quiet) + でしょう → 静かじゃないでしょう (shizuka janai deshou)
• な-Adjective (Past Affirmative): 静かだった (shizuka datta, was quiet) + でしょう → 静かだったでしょう (shizuka datta deshou)
• な-Adjective (Past Negative): 静かじゃなかった (shizuka janakatta, wasn’t quiet) + でしょう → 静かじゃなかったでしょう (shizuka janakatta deshou)

• Noun (Present Affirmative): 学生 (gakusei, student) + でしょう → 学生でしょう (gakusei deshou)
• Noun (Present Negative): 学生じゃない (gakusei janai, not a student) + でしょう → 学生じゃないでしょう (gakusei janai deshou)
• Noun (Past Affirmative): 学生だった (gakusei datta, was a student) + でしょう → 学生だったでしょう (gakusei datta deshou)
• Noun (Past Negative): 学生じゃなかった (gakusei janakatta, wasn’t a student) + でしょう → 学生じゃなかったでしょう (gakusei janakatta deshou)

~でしょう vs. ~だろう: Politeness Matters

Remember, ~でしょう is the polite form, suitable for most general conversations, especially with people you don’t know well or those in a higher position. ~だろう is its plain, informal counterpart, used among close friends, family, or in situations where politeness isn’t strictly required. While the meaning is generally the same, the choice between the two significantly impacts the tone and social appropriateness of your speech.

Diving Deeper: The Multifaceted Uses of “~でしょう”

This is where ~でしょう truly shines! It’s not a one-trick pony; it has several important functions in Japanese communication. Let’s explore them with real-world examples.

1. Expressing Conjecture or Probability (推量: Suiryō)

This is arguably the most common use of ~でしょう. It allows the speaker to express a prediction, an assumption, or an educated guess about a future event or a current situation. It implies that the speaker has some basis for their belief, but isn’t 100% certain.

Example 1: Predicting the Weather

明日、雨が降るでしょう。 (Ashita, ame ga furu deshou.)
English Translation: It will probably rain tomorrow.
Explanation: You might hear this on a weather forecast or say it if you’ve checked the forecast. You’re not absolutely certain it will rain, but based on the information available (e.g., weather report, dark clouds), you believe it’s highly likely. It’s a polite and neutral way to state a probability.

Example 2: Assuming a Friend’s Arrival

田中さんはもう家に着いたでしょう。 (Tanaka-san wa mou ie ni tsuita deshou.)
English Translation: Mr. Tanaka has probably arrived home already.
Explanation: You know Mr. Tanaka left work an hour ago and his house is only a 30-minute commute. Based on this information, you can reasonably assume he’s already home. You’re expressing your high probability estimation without absolute certainty.

Example 3: Assessing a Situation

この問題は難しいでしょう。 (Kono mondai wa muzukashii deshou.)
English Translation: This problem is probably difficult. / This problem will likely be difficult.
Explanation: You’ve seen similar problems before, or perhaps the person attempting it looks puzzled. You’re making an assessment based on your observations or general knowledge, expressing your belief about its difficulty. This is a softer way to state your opinion compared to a direct “This problem is difficult.”

2. Seeking Confirmation or Agreement (確認・同意の求め: Kakunin・Dōi no Motome)

When used with a rising intonation (like a question), ~でしょう transforms into a way to ask for confirmation or agreement. The speaker usually believes their statement is true and is looking for the listener to confirm it or concur. It’s softer and more indirect than a direct question with 「か」 (ka).

Example 4: Confirming Someone’s Status

あなたは学生でしょう？ (Anata wa gakusei deshou?)
English Translation: You are a student, aren’t you?
Explanation: You might have a strong feeling or some prior indication that the person is a student (e.g., they’re young, carrying a backpack, at a university event). You’re asking for confirmation, expecting them to say “yes.” This is much softer than 「あなたは学生ですか？」 (Are you a student?), which can sound more direct or even interrogative.

Example 5: Seeking Agreement on Taste

このケーキ、美味しいでしょう？ (Kono keeki, oishii deshou?)
English Translation: This cake is delicious, isn’t it?
Explanation: You think the cake is delicious and you want your listener to agree with you. You’re inviting them to share your positive opinion. It’s a way of sharing an experience and building rapport.

Example 6: Gently Reminding Someone

明日は会議がありますでしょう？ (Ashita wa kaigi ga arimasu deshou?)
English Translation: There’s a meeting tomorrow, right?
Explanation: You’re reminding someone about an upcoming meeting, possibly because you think they might have forgotten or you want to ensure they’re prepared. The ~でしょう softens the reminder, making it sound less like an accusation and more like a gentle prompt or shared knowledge.

3. Making a Soft Suggestion or Gentle Persuasion (提案・呼びかけ: Teian・Yobikake)

While ~ましょう (~mashou) is the primary form for direct suggestions (“Let’s do X”), ~でしょう can sometimes be used to make a softer, more indirect suggestion, or to gently nudge someone towards an action by stating a probable outcome or a shared understanding of a situation.

Example 7: Suggesting a Break

疲れたでしょう。少し休みましょう。 (Tsukareta deshou. Sukoshi yasumimashou.)
English Translation: You must be tired. Let’s rest a bit.
Explanation: The first part, 疲れたでしょう, confirms the listener’s state (you assume they are tired) and sets the stage for the suggestion. It’s a very empathetic way to suggest taking a break, acknowledging their condition first.

Example 8: Encouraging Someone

頑張ればできるでしょう。 (Ganbareba dekiru deshou.)
English Translation: If you try hard, you can probably do it. / You’ll be able to do it if you try hard.
Explanation: This is an encouraging statement. You’re not just saying “you can do it” (できる), but adding ~でしょう implies a high probability of success given effort, which can be very motivating. It’s a gentle form of persuasion, boosting confidence.

4. Expressing Mild Doubt or Uncertainty (軽い疑問・不確実性: Karui Gimon・Fukakujitsusei)

Sometimes, ~でしょう can be used to express an opinion or observation with a hint of reservation, showing that the speaker is not entirely sure or wants to avoid sounding too assertive. It softens the statement, allowing for disagreement or alternative views.

Example 9: Expressing a Reserved Opinion

この色は彼に似合わないでしょう。 (Kono iro wa kare ni niawanai deshou.)
English Translation: This color probably doesn’t suit him.
Explanation: Instead of a blunt 「この色は彼に似合わない」 (This color doesn’t suit him), adding ~でしょう makes your opinion sound less definitive. It leaves room for someone else to say, “No, I think it actually looks good on him.” It’s a way to express a subjective thought without being confrontational.

Common Pitfalls and How to Avoid Them

While ~でしょう is incredibly useful, mastering it means understanding its nuances and avoiding common mistakes. Here are some key points to keep in mind:

1. “~でしょう” vs. “~だろう”: Navigating the Politeness Spectrum

As mentioned, ~でしょう is polite, and ~だろう is plain. The biggest mistake is using ~だろう in formal settings or with strangers/superiors, or using ~でしょう in casual conversations with close friends, which can sound overly formal or even sarcastic. Always consider your relationship with the listener and the context.

• Formal/General: 明日は雨が降るでしょう。(Ashita wa ame ga furu deshou.) – Polite prediction.
• Informal/Casual: 明日は雨が降るだろうね。(Ashita wa ame ga furu darou ne.) – Casual prediction with friends.

2. “~でしょう” vs. “~と思います”: The Difference in Conviction and Source

Both express belief, but there’s a subtle yet important difference:

• ~でしょう: Implies a higher degree of objective probability or likelihood based on external information, common sense, or a reasonable deduction. It’s often a prediction or a shared assumption.
• ~と思います (~to omoimasu): Expresses the speaker’s personal opinion or thought. While it can also imply probability, the emphasis is on the speaker’s subjective internal process (“I think…”). The conviction level can vary.

Comparison:

• A: 明日は雨が降るでしょう。 (Ashita wa ame ga furu deshou.)
  “It will probably rain tomorrow.” (Based on the weather forecast or dark clouds; sounds more like a factual prediction.)
• B: 明日は雨が降ると思います。 (Ashita wa ame ga furu to omoimasu.)
  “I think it will rain tomorrow.” (Based on my personal feeling or observation; more subjective.)

You can sometimes use both to express a nuanced idea: 「明日は雨が降るでしょう。私はそう思います。」 (It will probably rain tomorrow. I think so.)

3. “~でしょう” vs. “~かもしれません”: Understanding Probability Levels

These two expressions both convey uncertainty, but they indicate different levels of probability:

• ~でしょう: Suggests a relatively high probability; “probably,” “likely.” You have a good reason to believe it.
• ~かもしれません (~kamoshiremasen): Suggests a lower probability; “might,” “perhaps,” “possibly.” There’s a chance, but it’s not as certain.

Comparison:

• A: 彼は来るでしょう。 (Kare wa kuru deshou.)
  “He will probably come.” (You expect him to come, high likelihood.)
• B: 彼は来るかもしれません。 (Kare wa kuru kamoshiremasen.)
  “He might come.” (There’s a possibility, but less certain.)

4. “~でしょう” vs. “~そうです” / “~ようです”: Distinguishing Information Sources

These expressions also deal with conjecture or appearance but differ significantly in their source of information.

• ~そうです (~sou desu – hearsay): “I hear that…”, “It is said that…” The information comes from someone else.
• ~そうです (~sou desu – appearance): “It looks like…”, “It appears that…” Based on direct visual observation.
• ~ようです (~yō desu): “It seems like…”, “It appears that…” Based on indirect evidence, intuition, or a comprehensive impression.
• ~でしょう: Based on the speaker’s own reasoning, deduction, or general knowledge. It’s the speaker’s personal (but often well-founded) conjecture.

Comparison: Imagine your friend, Ken, who usually goes to bed early.

• A: ケンはもう寝たでしょう。 (Ken wa mou neta deshou.)
  “Ken has probably gone to bed already.” (Your own logical deduction based on knowing Ken’s habits.)
• B: ケンはもう寝たそうです。 (Ken wa mou neta sou desu.)
  “I hear that Ken has gone to bed already.” (Someone told you this.)
• C: ケンはもう寝たようです。 (Ken wa mou neta yō desu.)
  “It seems Ken has gone to bed already.” (You called his house, and no one answered, or his lights are off; indirect evidence.)

5. Intonation is Key!

The meaning of ~でしょう can change dramatically based on your intonation. A rising intonation at the end turns it into a question seeking confirmation, while a falling intonation signifies a conjecture or statement of probability.

• Falling intonation: 明日は晴れるでしょう。(Ashita wa hareru deshou.) – “It will probably be sunny tomorrow.” (A statement.)
• Rising intonation: 明日は晴れるでしょう？(Ashita wa hareru deshou?) – “It will be sunny tomorrow, right?” (Seeking confirmation.)

In written Japanese, a question mark often clarifies this, but in spoken Japanese, intonation is your only guide.

6. Avoiding Overuse and Awkwardness

While ~でしょう is polite, avoid overusing it. If a fact is obvious or already mutually known, adding ~でしょう can sound redundant or even slightly condescending, as if you’re stating the obvious and seeking confirmation for it. For instance, if you’re both watching the rain, saying 「雨が降っていますでしょう？」 (It’s raining, isn’t it?) might feel a bit odd, though not necessarily wrong. A simple 「雨ですね」 (It’s raining, isn’t it?) would be more natural.

Practice Makes Perfect: Test Your Understanding

Now that you’ve absorbed all this information, let’s put your knowledge to the test! Fill in the blanks with the appropriate form of ~でしょう or ~だろう, considering the context and politeness level. If a question mark is present, assume a rising intonation.

Exercise 1: Fill in the Blanks

1. 彼はまだ来ていません。きっと電車が遅れている（　　　）。 (He hasn’t come yet. The train is probably delayed.)
2. あなたは日本語が上手（　　　）？ (You are good at Japanese, aren’t you?)
3. この仕事は今日中に終わる（　　　）。 (This work will probably finish today.)
4. A: 明日のパーティー、山田さんは来ますか？ B: さあ、来るかどうか分かりません。でも、仕事が終われば来る（　　　）。 (A: Is Yamada-san coming to tomorrow’s party? B: Well, I don’t know if he’ll come. But if he finishes work, he’ll probably come.)
5. 今日はとても寒い。雪が降る（　　　）。 (It’s very cold today. It will probably snow.)

Exercise 2: Choose the Best Option

Read the scenario and choose the most natural and appropriate option from the choices given.

Scenario: You’re talking to your Japanese friend, Ken, about a new movie that just came out. You know Ken loves action movies.

あなた: 「新しいアクション映画、もう見た？ケン、ああいう映画が好きだから、もう見た（　　　）。」

1. a) だろうね。
2. b) でしょうか？
3. c) かもしれません。

Scenario: You are at a business meeting. Your colleague, Ms. Sato, presents a new proposal. You want to politely ask her for confirmation about a detail.

あなた: 「佐藤さん、このデータは去年のもので間違いありません（　　　）？」

1. a) だろう？
2. b) でしょうか？
3. c) と思います。

Answers and Explanations

Exercise 1:

1. 彼はまだ来ていません。きっと電車が遅れているでしょう。(or だろう for informal)
   Explanation: Expressing a high probability based on the situation.
2. あなたは日本語が上手でしょう？
   Explanation: Seeking confirmation with a polite tone.
3. この仕事は今日中に終わるでしょう。(or だろう for informal)
   Explanation: Making a prediction about completing work.
4. A: 明日のパーティー、山田さんは来ますか？ B: さあ、来るかどうか分かりません。でも、仕事が終われば来るでしょう。(or だろう for informal)
   Explanation: Expressing a probable outcome given a condition.
5. 今日はとても寒い。雪が降るでしょう。(or だろう for informal)
   Explanation: Making a prediction based on current conditions.

Exercise 2:

Scenario 1 Answer: 1) だろうね。
Explanation: Since you’re talking to a friend (Ken) and you’re making a strong assumption about his actions based on his known preferences, the informal だろうね is the most natural fit. 「でしょうか？」 would be too formal, and 「かもしれません」 expresses lower probability, which doesn’t fit the strong assumption.

Scenario 2 Answer: 2) でしょうか？
Explanation: In a business meeting, politeness is paramount. 「でしょうか？」 is the most appropriate and polite way to seek confirmation from a colleague. 「だろう？」 is informal and rude in this context, and 「と思います」 states your opinion, not seeks confirmation.

Wrapping Up: Embrace the Power of “~でしょう”

Congratulations! You’ve navigated the intricate world of ~でしょう. This seemingly simple grammar point is a powerhouse for expressing a wide range of emotions and intentions, from confident predictions to gentle inquiries. By understanding its structure, various uses, and how it compares to similar expressions, you’ve equipped yourself with a crucial tool for natural and effective Japanese communication.

Remember, mastering grammar isn’t just about memorizing rules; it’s about understanding context, nuance, and the subtle art of conveying your message. Continue to practice using ~でしょう in your daily conversations, try to identify it in Japanese media, and don’t be afraid to make mistakes – they are essential steps on your learning journey.

Keep studying diligently for your JLPT exams, and know that every grammar point you conquer brings you closer to fluency. You’re doing great, and your Japanese communication skills will undoubtedly blossom!

If you are interested in the Complete JLPT N4 guide, please take a look at this article.