What does using という add to a sentence?


This sentence is from a grammar website:

主人公が犯人だったというのが一番面白かった。

Why is という necessary?

What does it add?

And what meaning is lost in writing the sentence without it? For example, as
in:

主人公が犯人だったのが一番面白かった。




In The Structure of the Japanese Language, Susumu Kuno's treatment of `こと`,
`の`, `ということ` and `というの` as complementizers separates them into two categories
- one involving presupposition and one without.

All the four forms listed above can be used when there is presupposition of
truth. But `こと` and `の` cannot be used when the predicate does not contain
presupposition.

I'm going to attempt to summarise some of that here but his analysis is
actually much more complete.

* * *

Observe this example taken from his book:

> [1] It **is probable** that John hit Mary:
>
> a. ジョンがマリを殴った​｛こと・の｝はありうることだ。 (Unacceptable)
>
> b. ジョンがマリを殴った​｛ということ・というの｝はありうることだ。 (Acceptable)
>
> [2] It **is false** that John hit Mary:
>
> a. ジョンがマリを殴った​｛こと・の｝は嘘だ。 (Unacceptable)
>
> b. ジョンがマリを殴った​｛ということ・というの｝は嘘だ。 (Acceptable)

What is observed is that in the 1a and 2a, `こと` and `の` cannot be used because
"is probable" and "is false" indicates that the speaker does not presuppose
the event of "John hit Mary" to be true.

I shall not include the complete analysis of `こと`, `の` and `と` but in summary:

  * `こと` and `の` assumes that the event is true, while `と` does not.

Also summarising the analysis of `こと` and `の`:

  * `の` represents a tangible action/state that is directly perceptible (by the five senses), while `こと` does not and instead represents a more abstract concept.

* * *

So in fact there is a slight difference in meaning.

Comparing:

  1. 主人公が犯人だった **の** が一番面白かった。 (主人公が犯人だった is presupposed to be true)

  2. 主人公が犯人だった **というの** が一番面白かった。 (There is no presupposition) Or (主人公が犯人だった is presupposed to be true)




In The Structure of the Japanese Language, Susumu Kuno's treatment of `こと`,
`の`, `ということ` and `というの` as complementizers separates them into two categories
- one involving presupposition and one without.

All the four forms listed above can be used when there is presupposition of
truth. But `こと` and `の` cannot be used when the predicate does not contain
presupposition.

I'm going to attempt to summarise some of that here but his analysis is
actually much more complete.

* * *

Observe this example taken from his book:

> [1] It **is probable** that John hit Mary:
>
> a. ジョンがマリを殴った​｛こと・の｝はありうることだ。 (Unacceptable)
>
> b. ジョンがマリを殴った​｛ということ・というの｝はありうることだ。 (Acceptable)
>
> [2] It **is false** that John hit Mary:
>
> a. ジョンがマリを殴った​｛こと・の｝は嘘だ。 (Unacceptable)
>
> b. ジョンがマリを殴った​｛ということ・というの｝は嘘だ。 (Acceptable)

What is observed is that in the 1a and 2a, `こと` and `の` cannot be used because
"is probable" and "is false" indicates that the speaker does not presuppose
the event of "John hit Mary" to be true.

I shall not include the complete analysis of `こと`, `の` and `と` but in summary:

  * `こと` and `の` assumes that the event is true, while `と` does not.

Also summarising the analysis of `こと` and `の`:

  * `の` represents a tangible action/state that is directly perceptible (by the five senses), while `こと` does not and instead represents a more abstract concept.

* * *

So in fact there is a slight difference in meaning.

Comparing:

  1. 主人公が犯人だった **の** が一番面白かった。 (主人公が犯人だった is presupposed to be true)

  2. 主人公が犯人だった **というの** が一番面白かった。 (There is no presupposition) Or (主人公が犯人だった is presupposed to be true)

