Explanatory わけだ

Last time, you learned how to express doubts in various ways, e.g. “日に本ほん語ごは難むずかしいのかな (I wonder if the Japanese language is difficult),” and “日に本ほん語ごは簡単かんたんなんじゃないか (I suppose the Japanese language is easy).” As you can see, the explanatory のだ often appears in a lot of sentence patterns to give some nuances. In this lesson, you will learn a related expression わけだ.

Explanation for How the Explanatory わけだ Works

The origin of わけだ comes from the kanji 訳わけ which means “reason,” “cause,” and “meaning.” Thus, it’s sometimes written in kanji like this 訳わけだ, but usually the hiragana version is preferred. The essential function of the explanatory わけだ is the same as the explanatory のだ, which is to contextually connect two sentences like “漢かん字じは勉べん強きょうしたくない。難むずかしいんだ。 (As for kanji, I don’t want to study it because it’s difficult).” Let’s check what わけだ can express in detail.

Conjugation Rule

先生せんせいなわけ（だ / です）
元げん気きなわけ（だ / です）
若わかいわけ（だ / です）
走はしるわけ（だ / です）

The conjugation of わけだ is very simple. Just like のだ, you can directly attach わけだ to i-adjectives and verbs. For nouns and na-adjectives, you add な.

先生せんせいなわけだから、
先生せんせいなわけなので、
先生せんせいなわけで、

When you make compound sentences, you will conjugate the last だ of わけだ. The explanatory わけだ sometimes appears in subordinate clauses.

Affirmative Sentences

Conclusions Based on a Guess

The first function is to indicate your conclusion based on your guess. With the example above, the context may be something like you try to launch a rocket in order to do a survey about Mars. Then, after you saw the explosion, you guessed the experiment failed. The phrase という sometimes appears before わけだ like 失敗したというわけだ. If that is the case, you don’t have to attach な to nouns and na-adjectives.

The explanatory のだ has the function of indicating discovery. Thus, you can replace わけだ with のだ, but the nuance will be different.

わけだ and のだ are sometimes used together, then the meaning is the same as わけだ. We don’t recommend doing so when you attach わけだ to nouns and na-adjectives. The multiple な makes sentences difficult to pronounce (*Look at the second example below).

You can also use わけだ when responding. Phrases which are the counterpart to “that is to say” and “so that means” are often used together. つまり and ということは are one of the typical phrases.

Expressing “Makes Sense”

The second function is to express “makes sense.” English translations don’t work well here. With the above example, わけだ is used because you have fully understood why Tanaka-san has become a singer after hearing his song, like “The fact (that he has become a singer) makes sense to me now.” わけだ and the adverb 道どう理りで which indicates “no wonder” or “it’s reasonable that…” is often used together. In this context, という doesn’t appear.

You cannot replace わけだ with のだ in this function. However, はずだ is interchangeable.

Summary (Rewording)

The third function is to express summaries (rewording) just like のだ. You can roughly consider this as the equivalent to “in other words” in English. In this context, わけだ and のだ are interchangeable. 

Interrogative Sentences

Asking Whether You Can Conclude Something Based on a Guess

わけだ only works in the first function (Conclusions Based on a Guess) in affirmative sentences. It’s a very contextual question, which is to ask whether or not you can conclude something based on your guess. With the above example, you guessed that Mr. A has never been abroad based on the fact that he has never taken a flight and asked whether you can conclude that your guess is correct. Without such contexts, you cannot use わけだ in interrogative sentences.

You can replace わけだ with のだ here.

Negative Sentences

We showed you some negative sentences, e.g. 明日からボブはいないわけだ and 試合に勝てないわけだ. We have conjugated the verbs so far and they are plain negative sentences; however, you can actually conjugate わけだ like わけじゃない and わけがない and express various nuances in negative sentences. Let’s learn the sentence patterns.

…わけに（は・も）いかない: Improperness or Impossibility

This sentence pattern indicates improperness or impossibility like “it’s not proper that…” or “it’s not possible that…” In general, you need to use volitional verbs here. The three, which are わけに, わけには, and わけにも, have the same nuance.

…わけがない: Strong Negation

This is related to the second function (Expressing “Make Sense”) in affirmative sentences and is roughly translated as “it’s unreasonable that…” or “there is no reason that…” Be careful. The level of negation is high.

You can reword them by using はずがない.

…わけではない: Denying Conclusions Based on a Guess

…わけではない has two functions. One of the two is related to the first function in affirmative sentences (Conclusions Based on a Guess). With the above example, you deny people’s guess that the experiment has failed. You may consider this as the counterpart “it doesn’t mean” in English. There is a typical combination which is to utilize “…（だ）からといって: just because.”

The second function is related to partial negation. We will carefully pick it up in the next lesson.

Summary

1. In affirmative sentences, the explanatory わけだ expresses;
   • conclusions based on a guess
   • "makes sense”
   • summaries (rewording)
2. In interrogative sentences, the explanatory わけだ asks whether or not you can conclude based on your guess.
3. In negative sentences, the explanatory わけだ expresses;
   • improperness or impossibility
   • strong negation
   • denying conclusions based on a guess

Now you know the two types of explanatory expressions. We hope that the functions are not difficult for you. As you can see the above, the explanatory わけだ has some very important roles in affirmative and negative sentences. In addition, わけだ is greatly involved with partial negatives. In the next lesson, you will learn more about negative sentences.