一度（も・でも・さえ・こそ）会ったことがあれば、友だちだと考える人がいる

Question

Japanese

「新完全マスター文法　日本語能力試験Ｎ３」という文法の教科書の１４８ページに、 次の文法問題が書いてあります。

一度（　　　）会ったことがあれば、友だちだと考える人がいる。

１　も　　　　２　でも　　　　３　さえ　　　　４　こそ

私は「３　さえ」を選びましたが、正解は「２　でも」です。

私の分析

この本の３２ページに、「３　さえ」について次の説明があります。

〜さえ〜ば…・〜さえ〜なら…

「〜が実現すれば、それだけで…が実現する。」 「〜さえ〜ば（なら）」は…が成り立つための必要最低限の条件を示す。

この説明は同じページに書いてある例文と一致します。

太郎は漫画さえ読んでいれば退屈しないようだ。

体さえ丈夫ならどんなことにも挑戦できる。

一言「ごめんなさい。」と言いさえすれば、相手は許してくれるだろう。

私は上の文法問題の文は次の意味だと思います。

(?) 一度さえ会ったことがあれば、友だちだと考える人がいる。

「一度会ったことがある」は「友だちだ」が成り立つための必要最低限の条件を示す。

それに対して、５８ページで「２　でも」については次の説明があります。

極端な例を出して、ほかは当然だと暗に示す。

私は上の文のどの部分が「当然だと暗に示す」か分かりませんので、それとこの説明の関係はよく分かりません。

質問

正解はなぜ「３　さえ」ではなく、「２　でも」なのでしょうか。私は「さえ」や「でも」の意味かニュアンスについて、何か間違いをしているのでしょうか。

English

I encountered the following multiple-choice question in my JLPT N3 grammar book 「新完全マスター文法　日本語能力試験Ｎ３」 (p. 148):

一度（　　　）会ったことがあれば、友だちだと考える人がいる。

１　も　　　　２　でも　　　　３　さえ　　　　４　こそ

I chose 「３　さえ」, but the answer given is 「２　でも」.

My analysis

On p. 32 of the same book, the choice 「３　さえ」 is explained as follows:

〜さえ〜ば…・〜さえ〜なら…

If ~ happens or is done, then ... is all that needs to be done. The phrase 「〜さえ〜ば（なら）」 is used to indicate the minimum conditions necessary for ... to take place.

Incidentally, the English translation seems a bit off for me; I understand it to mean

... happens/is done as long as ~ happens/is done.

or, in other words,

For ... to happen/be done, ~ is all that needs to happen/is done.

which seems to align with the examples given on the same page:

太郎は漫画さえ読んでいれば退屈しないようだ。

It seems that Tarō is not bored as long as he is reading manga.

体さえ丈夫ならどんなことにも挑戦できる。

(I) can take on any challenge as long as (my) body is strong.

一言「ごめんなさい。」と言いさえすれば、相手は許してくれるだろう。

Perhaps saying the simple word "sorry" is all that needs to be done in order for your partner to forgive you.

I understood the given sentence to mean

(?) 一度さえ会ったことがあれば、友だちだと考える人がいる。

There are people who think that (people) are friends as long as they have met once.

which seems to align with this usage of さえ.

The choice 「２　でも」, on the other hand, is explained as follows on p. 58:

Used to imply or show by extreme example that something is obvious.

which does not seem to connect with the given sentence — I don't see what part is supposed to be "obvious" here.

Questions

Why is the answer でも rather than さえ? What meanings and nuances of さえ and でも am I missing here?

Answer 1

So this is my very premature understanding and I'm sure better answers will come from more knowledgeable contributors later, but let me just leave my two cents here.

My first thought was: with 2 the sentence sounds natural and with 3 it sounds a bit strange. There's an ever so nuanced difference here I'm sensing that separates the sentence in question apart from the examples sentence for さえ that you cite from 『新完全マスター文法』. I'm not sure I can explain it well but I'm going to take a crack at it any way.

さえ has two usages, and here we are focusing on さえ + conditional ば or なら. In simplest terms, this usage describes a condition which if and when satisfied the following statement will stand. It may sound like I just repeated what your textbook says in that grammar point, but not really. Your grammar book's comment claims さえ gives 成り立つための必要最低限の条件, which I disagree. It has always puzzled me why some grammar books repeat and promulgate a claim that I consider inaccurate. I think さえ actually gives a much stronger condition than some grammar books are willing to give it credit for. The condition followed by さえ isn't necessarily a sine qua non, a necessary condition in mathematical terms, but closer to a sufficient condition.

Consider this sentence:

君さえいれば他には何もいりません
As long as you are here (with me), I don't need anything else.

Looking at this sentence we can see さえ gives a pretty strong condition. The description 成り立つための必要最低限の条件 is definitely misleading if not logically incoherent or misguided.

Now let's look at two other real-world examples with さえ:

ブリーチ一回さえできれば大概のことは出来ます！(source)

このスキルのクール時間が長いため一回さえ乗り越えれば、あとは安泰だ。(source)

わざわざ応募する必要がなく、プレイさえしたことがあれば全員が対象になります。(source)

I intentionally picked sentences that resemble your sentence at issue in construction. In all the sentences, once the さえ condition is met, the following activity/claim is stated with confidence.

I know at this point you are probably pointing to this example sentence from your book and grumbling about how it also contained a speculative statement:

一言「ごめんなさい。」と言いさえすれば、相手は許してくれるだろう。

Yes, it is true だろう takes away some of the certainty, but it is still a statement that gives one possibility and is focused on that possibility. だろう here is a hedge that softens the claim but doesn't change the logical structure: A さえ～ば/なら B. Once A is satisfied/met, B.

Let's look at the sentence in question:

(?) 一度さえ会ったことがあれば、友だちだと考える人がいる。

A さえ～ば-> when A is met, there are some people who consider B is true. This doesn't sound like sufficiency-based logic like all the さえ～ば examples we have seen.

I guess I'd feel better about this sentence:

一度さえ会ったことがあれば、友だちになる。