わけ in this sentence?


> どうやったら、この局面でこの指し手になるわけだ？

I'm not sure what this わけ could be. The fact that this is a question bothers
me a bit.




jisho.org [here](http://jisho.org/search/%E3%82%8F%E3%81%91) defines that
訳｛わけ｝ is as follows:

> ### 訳｛わけ｝
>
> noun  
>  conclusion from reasoning, judgement or calculation based on something read
> or >heard; reason; cause; meaning; circumstances; situation​

My attempt is as follows:

> どうやったら、この局面でこの指し手になる **わけ** だ？  
>  _How could you choose this move in the state of the game?_

My attempt means that I could not understand the **reason** why you
chose/decided this move in the state of the game.

* * *

# Bonus

> (0) どうやったら、この局面でこの指し手になるわけだ？

I think that the above-mentioned Japanese sentence of (0) posted by the
questioner is not necessarily good, is different from the ordinary way of
expressions, or extremely speaking it is a bad sentence, so I will add
explanations to (0) and introduce some correct Japanese sentences for those
who are studying Japanese.

  1. The sentence of (0) is one said in the following situation.  
The situation is a scene of a game of 将棋{しょうぎ} _Shogi_ , 囲碁｛いご｝ _Igo_ or チェス
_Chess_. In the scene of the game, one of the opponents moved a certain piece.
However, the move was considerably out of expectation or unpredictable from
the established tactic or usual method generally considered in the situation
of the game. In this awesome situation, the phrase of (0) was uttered by the
opponent of the game or by a third party watching this game with surprising
and/or confused emotions.

  2. Usually "どうやったら" could be used in a phrase like " **どうやったら** この機械を操作できるか？ _How can I manipulate this machine?_ " or " **どうやったら** この岩を動かすことができるか？ _How can I move this rock?_ "  
In general this phrase is an expression related to concrete behavior so that
it can be paraphrased like "どのようにしたら（何かができる） _how to do/behave (to be able to
do something)._ " or "どういう手段を使ったら _what kind of means to use "to be able to do
something_". However, in the sentence of (0), this phrase is used as an
expression related to mental or intelligent activity, and I think that it can
be paraphrased as "どのように考えたら _how to think (to do something)_ " or
"どういう理屈があったら _what kind of reasons could lead (to do something)_ ".

  3. " **局面｛きょくめん｝** " is generally used as "situation aspect of an affair; situation", and it is a word came from a game such as Shogi, Igo or Chess meaning "position in a game of Shogi, Igo or Chess; state of the game", so as for the sentence of (0), it is used as the meaning of its origin.

  4. " **指{さ}し手｛て｝** " means a certain **move** of a piece (in Shogi, Igo, Chess, etc.). Strictly speaking, "move" could be used safely for Shogi and Chess because they are games where players move pre-placed pieces, but as for Igo, they additionally place white or black stones, which are equivalent to pieces in Shogi or Chess, on the surface of a board, so "指{さ}し手｛て｝" in Igo means "placing a stone at a certain place on the surface of the game board" instead of a "move of a piece".

I know that an interrogative use of "訳｛わけ｝だ？" is rare in general Japanese.
Therefore I searched for sentences including "訳｛わけ｝だ" in a famous corpus named
"[少納言]｛Shounagon｝", and the result is as follows, where sentences in which
訳｛わけ｝だ is used with the same meaning are excluded from the result.

① ベガの意識の中では、ゲージはトイレだった事になる。その「ゲージ」で寝かして居た **訳だ** ！ ② 不吉なイメージなのでこの曲には不適切な
**訳だ** ！と言っていました。  
③ これで、マリオワールドの世界を一周したことになる **訳だ** ！  
④ マイク・シーガーもお爺ちゃんになっちゃいました。私も歳を取る **訳だ** ・・・（＾ω＾）  
⑤ 姿が見えなくてもおかしくないと思っている **訳だ**  
⑥ その突堤の先端は、十三号艇の碇泊している箇所にずっと近付ける **訳だ** 。  
⑦ 大寺さんにはさっぱり判らない。―どう云う **訳だろう？** と大寺さんは細君に云った。  
⑧ サウナに入り、からっからっに乾いたページをめくりながら、旅の汗を流せ、とでもいう **訳だろうか** 。

Among more than 290 example sentences, ⑦ and ⑧ are only two interrogative
sentences. Therefore, it seems that the ending part of the sentence posted by
the questioner should be like "～この指し手になる **わけだろうか？** " as correct Japanese.

Based on the above analysis, if the sentence of (0) is rewritten to correct
Japanese that is easy to understand, it becomes like the following (1) to (4).

Original:

> (0) どうやったら、この局面でこの指し手になるわけだ？

My attempts:

> (1) どのように考えたら、この局面でこの指し手になるわけだろうか？  
>  (2) どのように考えたら、この局面でこの指し手が正当であるという理屈になるのだろうか？  
>  (3) どういう理由があって、この局面でこの指し手になるのだろうか？  
>  (4) どういう理屈/理由に基づいて、この局面でこの指し手になるのだろうか？




jisho.org [here](http://jisho.org/search/%E3%82%8F%E3%81%91) defines that
訳｛わけ｝ is as follows:

> ### 訳｛わけ｝
>
> noun  
>  conclusion from reasoning, judgement or calculation based on something read
> or >heard; reason; cause; meaning; circumstances; situation​

My attempt is as follows:

> どうやったら、この局面でこの指し手になる **わけ** だ？  
>  _How could you choose this move in the state of the game?_

My attempt means that I could not understand the **reason** why you
chose/decided this move in the state of the game.

* * *

# Bonus

> (0) どうやったら、この局面でこの指し手になるわけだ？

I think that the above-mentioned Japanese sentence of (0) posted by the
questioner is not necessarily good, is different from the ordinary way of
expressions, or extremely speaking it is a bad sentence, so I will add
explanations to (0) and introduce some correct Japanese sentences for those
who are studying Japanese.

  1. The sentence of (0) is one said in the following situation.  
The situation is a scene of a game of 将棋{しょうぎ} _Shogi_ , 囲碁｛いご｝ _Igo_ or チェス
_Chess_. In the scene of the game, one of the opponents moved a certain piece.
However, the move was considerably out of expectation or unpredictable from
the established tactic or usual method generally considered in the situation
of the game. In this awesome situation, the phrase of (0) was uttered by the
opponent of the game or by a third party watching this game with surprising
and/or confused emotions.

  2. Usually "どうやったら" could be used in a phrase like " **どうやったら** この機械を操作できるか？ _How can I manipulate this machine?_ " or " **どうやったら** この岩を動かすことができるか？ _How can I move this rock?_ "  
In general this phrase is an expression related to concrete behavior so that
it can be paraphrased like "どのようにしたら（何かができる） _how to do/behave (to be able to
do something)._ " or "どういう手段を使ったら _what kind of means to use "to be able to do
something_". However, in the sentence of (0), this phrase is used as an
expression related to mental or intelligent activity, and I think that it can
be paraphrased as "どのように考えたら _how to think (to do something)_ " or
"どういう理屈があったら _what kind of reasons could lead (to do something)_ ".

  3. " **局面｛きょくめん｝** " is generally used as "situation aspect of an affair; situation", and it is a word came from a game such as Shogi, Igo or Chess meaning "position in a game of Shogi, Igo or Chess; state of the game", so as for the sentence of (0), it is used as the meaning of its origin.

  4. " **指{さ}し手｛て｝** " means a certain **move** of a piece (in Shogi, Igo, Chess, etc.). Strictly speaking, "move" could be used safely for Shogi and Chess because they are games where players move pre-placed pieces, but as for Igo, they additionally place white or black stones, which are equivalent to pieces in Shogi or Chess, on the surface of a board, so "指{さ}し手｛て｝" in Igo means "placing a stone at a certain place on the surface of the game board" instead of a "move of a piece".

I know that an interrogative use of "訳｛わけ｝だ？" is rare in general Japanese.
Therefore I searched for sentences including "訳｛わけ｝だ" in a famous corpus named
"[少納言]｛Shounagon｝", and the result is as follows, where sentences in which
訳｛わけ｝だ is used with the same meaning are excluded from the result.

① ベガの意識の中では、ゲージはトイレだった事になる。その「ゲージ」で寝かして居た **訳だ** ！ ② 不吉なイメージなのでこの曲には不適切な
**訳だ** ！と言っていました。  
③ これで、マリオワールドの世界を一周したことになる **訳だ** ！  
④ マイク・シーガーもお爺ちゃんになっちゃいました。私も歳を取る **訳だ** ・・・（＾ω＾）  
⑤ 姿が見えなくてもおかしくないと思っている **訳だ**  
⑥ その突堤の先端は、十三号艇の碇泊している箇所にずっと近付ける **訳だ** 。  
⑦ 大寺さんにはさっぱり判らない。―どう云う **訳だろう？** と大寺さんは細君に云った。  
⑧ サウナに入り、からっからっに乾いたページをめくりながら、旅の汗を流せ、とでもいう **訳だろうか** 。

Among more than 290 example sentences, ⑦ and ⑧ are only two interrogative
sentences. Therefore, it seems that the ending part of the sentence posted by
the questioner should be like "～この指し手になる **わけだろうか？** " as correct Japanese.

Based on the above analysis, if the sentence of (0) is rewritten to correct
Japanese that is easy to understand, it becomes like the following (1) to (4).

Original:

> (0) どうやったら、この局面でこの指し手になるわけだ？

My attempts:

> (1) どのように考えたら、この局面でこの指し手になるわけだろうか？  
>  (2) どのように考えたら、この局面でこの指し手が正当であるという理屈になるのだろうか？  
>  (3) どういう理由があって、この局面でこの指し手になるのだろうか？  
>  (4) どういう理屈/理由に基づいて、この局面でこの指し手になるのだろうか？

