Special expressions with generic nouns

From JapaneseGuide

This addition is a paste from this thread, slightly edited. I thought that it would be very helpful to know the finer points of という. -Immacolata

How about an explanation of the differences between the interrelated uses the following:

というのは のは ということは ことは

The difference between them is crucial, and, yet, it seems that no grammars explain it. It took me forever to figure it out - not for want of such a mind as to comprehend, but for want of any resource such as actually explains the difference aptly...

==ということ == indicates something that is merely conceptual. A clause introduced by this in Japanese is commensurate to a substantive clause in the subjunctive in Latin and other Romance languages introducing an idea that is merely conceived of and which is not yet a fact or which may never be a fact. ("Mea nihil referat vt is talem rem fecerit." = "It shouldn't pertain to me at all that he should have done such a thing." (If he should do this, it wouldn't matter to me.))

誰かにそんなことが出来るということは考えられない。 That someone should be able to do such a thing is unthinkable.

==こと== indicates an actual fact or event. "That (the fact that) he did this angers me!" "Mea nihil refert qvod is id fecit" = "It doesn't pertain to me at all that he has done this."

映画を見て寝付いてしまったことは映画がつまらなかったということだ 　The fact that you fell asleep watching the movie means the movie was boring.

==というの== introduces the meaning of a phrase. A second という is absent in this sentence because the sentence only introduces an alternate phrasing of, or definition for the thing in question.

「アースホール」というのは何ですか？　　　What does "ass-hole" mean?

「プレイボイ」というのはよく女の子と遊ぶ人のことだ。 A "play-boy" is a person who habitually plays with girls

==という part 2== The second という　is present because the sentence introduces and interpretation of a phrase. This interpretation is different from the interpretation introduced by ということ/こと, which describes the potential corollary/ies of a fact or of an act merely conceived of or which has not yet occurred.

「猿も木から落ちる」というのは上手な人でも時には失敗することがあるということだ。 "Even monkeys fall from trees" means that even skillful people make mistakes on occasion.

==の== just nominalizes a phrase, making it available to be the topic, the subject of verb copula, the direct/indirect object of a sensory verb, or the subject of a verb.

彼が商店を出るのを見た。　　I saw him leave the store.

Sundry details regarding ということは　/　ことは

・ こと is not used when the event is unlikely to happen.

・If the event has not yet occurred, but is likely to happen, both ということ and こと can be used.

・If the event in question is one known through one's own direct experience, ということ can not be used. 彼が集まりに来なかったことは事実だ。

・If the event is fully hypostatized and is a fact, but is one learned through a third party, then ということ and こと are acceptable. 彼が離婚した (ことは/ということは) 事実だ。

・When verbs of demanding and feeling are involved,　ということ is never used. 何かよくないことが起こりつつあることを感じる。　　 我々は社長が謝罪することを要求した。

Then there are these uses of こと which are only peripherally related to the uses expounded above:

ことになる ことにする ことによる ことで こと　(formal imperative) ことはない ことが/はある