This lesson focuses on expressions which describe obvious situations, many of which roughly translate to "to say nothing of."
The adverb ましてや translates into English as either "to say nothing of" or "much less," showcasing an extreme situation that is all the more apparent to the speaker. The overall tone of the statement is highly negative, but the overall sentence is not limited to be using with the negative. It's just that the extreme being mentioned is not a positive one.
ましてや is compromised of the verb 増す meaning "to increase" and the bound particle や, which is used to add more of an emotional flare to the statements. Its use is optional, however, which allows the speaker to make the point that something is so blatantly obvious in a somewhat lighter fashion.
Although ましてや is often followed by a comma, it is in fact an adverb and should not be viewed as a conjunction. It is also worth noting that this phrase is not used so often in the spoken language despite the emotional punch it can pack. One reason for why it isn't used so much is the risk of using it towards a superior, which would be potentially very condescending at best depending on what you're vexed about.
Orthography Note: まして（や） is only seldom written in Kanji as 況して（や）.
He can't even read Japanese, much less write it or speak it.
She can hardly jog, much less being able to run.
Sensei: "The average for this test was 60"
A-kun: "Did you get over a 70?"
B-kun: "No way, I couldn't even make the average, much less get a 70 which is like a hopeless dream"
いわんや derives from the verb 言う meaning "to say" and the Old Japanese auxiliary verb ～む marking volition followed by the bound particle や. In Kanji, it is usually spelled as 況や, but in any event, because of its rather dated etymology, it should come as no surprise that it isn't used much outside of literature in Modern Japanese.
There are three syntactically different situations in which 況や can be found, two of which are only seen in 訓読文 (Kanbun converted into literary Japanese).
Even crows have the value of reciprocating nurture, and the same goes without being said for humans.
By even just residing in a remote, frontier town, disturbances that accompanied the times, both ups and downs, were unavoidable. The same can obviously be said about a person's lifetime.
From 濹東綺譚 by 永井荷風.
9a. この玉、たはやすくえ取らじを。いはんや、龍の頸に玉はいかが取らむ (Classical)
9b. この玉はたやすく取ることができないものだが・・・まして、竜の頸にある玉をどのように取ろうとするのだろうか。(Modern Japanese)
We can't just obtain the orb so easily. How do you suppose we even obtain the orb inside the dragon's neck?
From the 竹取物語.
It's unfeasible much less to kids.
Spelled in Kanji as 以ての外, this expression translates best as "absurd/ridiculous" despite its adverbial roots. Meaning, it functions as an adjectival noun. Grammatically, it's used no differently than if one were to take a sentence with まして・いわんや, dropping said sentence-initial adverb as well as the negative statement at the end and simplifying it to having もってのほか being sentence-final.
Saying that is just absolutely absurd.
Stains and wrinkles on untidy clothes are beyond absurd!
Because it is an adjectival noun, there is no need for there to be a clause before it. In fact, it can be used in the 連体形 with either な or の as any other 形容動詞.
Rebelling against the king is absurd conduct.
Read as なおさら, this adverb means "all the more" and can be used in both positive and negative contexts. It most frequently appears after conjunctions, but it can also appear at the end of the sentence in much the same way that 以ての外 can as an adjectival noun, but in other placements, it solely functions as an adverb.
Orthography Note: This phrase is usually spelled in Hiragana, but when it is spelled in Kanji, it may be seen written as either 尚更 or 猶更.
Getting up early is tough, and that is all the more so on days off.
Being told not to do something makes one want to do it all the more.
It is because that one is a manager at a measure company that results in making mistakes all the more not so good.
This expression is the word-for-word equivalent "it goes without saying." Having said that, considering Japanese word order, it goes without saying that this should go at the end of the sentence. It can, though, be repurposed into an adverb as 言うまでもなく.
It goes without saying that (his) parents figured it out.
It goes without saying that this guy is an idiot.
It goes without saying that that interpretation is a mistake.
It goes without saying that molestation is a crime.
Of course, the basic way of saying "obvious" in Japanese is still expressed with the adjectival noun 当然だ or 当たり前だ, which are completely interchangeable with each other, although one could also say that that too goes without saying.
Potential translations that don't use "obvious" include "(only natural)," "a given," "deserved," "right," etc.
It's a given that we won!
It's only natural to follow (the person) back.
To naturally do the obvious thing to do.
It was only natural that an explosion of infections occurred.
I think it's only natural to do as hard as you can.