有無を言わさず・有無を言わさぬ


I understand "対立する言葉", in this case 有無, however, I cannot yet grasp these
expressions:

> 有無を言わさず, 有無を言わせぬ, 言わさぬ.

The definition according to Weblio is:
相手の好むと好まざるとにかかわらず、物事を強いるさま。承知不承知を度外視して行わせるさま。「有無を言わせず」とも表記する。相手の諾否に関係なく。無理やり。有無を言わせず。

> 有無を言わさず、宣告を下す。  
>  == He/She was forcibly sentenced (no questions asked)

If I understood correctly, this sentence seems to agree with the definition.

However, some other sentences like:

> 有無を言わさぬ迫力があった。  
>  有無を言わさぬ口調だった。  
>  有無を言わさぬ物言いだった。

...seem to indicate that 有無を言わさぬ means: unspeakable; indescribable as in "too
much".

  1. Are my translations correct?
  2. Is 有無を言わさず identical to 有無を言わさぬ?
  3. Can you provide a few example sentences using 有無を言わさず・有無を言わさぬ




ず is the continuative form (連用形) of the negative auxiliary ぬ. It follows the
pre-nai/irrealis form (未然形). In other words, [ず and ぬ are different
conjugations of exactly the same
word](https://www.kokugobunpou.com/%E5%8A%A9%E5%8B%95%E8%A9%9E/%E3%81%AA%E3%81%84-%E3%81%AC-%E3%82%93/).
(Note that when ぬ follows a continuative form, it's a different [auxiliary for
perfective aspect](https://japanese.stackexchange.com/q/12585/5010) that
conjugates differently.)

The difference between ぬ and ず is simple; ず modifies something adverbially,
whereas ぬ modifies something attributively (aka adjectivally) or works as a
predicate. So 有無を言わせず is _forcibly_ and 有無を言わせぬ is _forcible_ , _undoubtable_
or _indescribable_ depending on the context (literally, "(which) doesn't let
[someone] say yes or no").

言わせる (ichidan) and 言わす (godan) are [two causative
forms](https://japanese.stackexchange.com/a/86621/5010) of 言う. They mean the
same thing, although 言わせる sounds more common in ordinary speech.

So we have the following combinations:

| 連用 (adverbial) | 連体 (attributive) | 終止 (predicative)  
---|---|---|---  
**言わす** | 有無を言わさ **ず** (に)働かせる  
有無を言わさ **ないで** 働かせる | 有無を言わさ **ぬ** 迫力  
有無を言わさ **ない** 迫力 | 彼は有無を言わさ **ぬ** 。  
彼は有無を言わさ **ない** 。  
**言わせる** | 有無を言わせ **ず** (に)働かせる  
有無を言わせ **ないで** 働かせる | 有無を言わせ **ぬ** 迫力  
有無を言わせ **ない** 迫力 | 彼は有無を言わせ **ぬ** 。  
彼は有無を言わせ **ない** 。  
  
Related: [What is the difference between the negative forms -ず and
-ぬ?](https://japanese.stackexchange.com/q/235/5010)

