は and も particle opposition

Question

は (pronounced as わ) being used in example sentences. This particle acts as a disambiguator when a sentence would otherwise be confusing in terms of who or what it was about, or what it was in relation to. For instance, [歩]{ある}かない and [今日]{きょう}は歩かない translate to "I do not walk" and "I won't be walking today" by virtue of the second sentence disambiguating the context from as broad as possible (i.e., 'in general'), to 'just today' (今日).

So in summary, we can characterise は as: [X]は[Y] → in the context of [X], [Y] applies, and outside the context of [X], [Y] does not apply. Put concisely, は not only tells us the applicable context, but also the inapplicable context. は never just marks applicable context, it always — always — also gives the inapplicable context simply by virtue of being used.

には
It should always be remembered that には disambiguates. It doesn't just specify a location or point/frame in time, but also adds a contrast between this location or time and every other.

も
This particle plays two important roles in Japanese. The first is that it acts as a similarity marker, and in this use it replaces the subject が or disambiguation marker は(source)

From reading this it seems like は and も are exactly the opposite. While も can be translated as too, also, it implies that you talk about more than one thing.

Isn't は kind of like the opposite? It implies that you refer to only one thing and nothing else?

For example :

ロンもジョンが買ったりんごを食べた。
Speaking of Ron, he too ate the apple that John bought.

This sounds easy to me, very easy and I understand immediately that: も implies that someone else other than ロン ate and at the same time that we are talking about ロン and someone else.

ロンはジョンが買ったりんごを食べた。
Speaking of Ron, only he ate the apple that John bought.

This sounds a little trickier to me, but re-reading it gets the meaning across. This sentence is the complete opposite of も or am I wrong? While も shows that you talk about X and Y, は is the opposite. It shows that you are talking about X but not Y.
So while も implies similarity and plurality, は implies peculiarity and singularity for what it marks.

The same happens with Particle+も/は.

ロンにもジョンが買ったりんごが食べられる。
Speaking of Ron, he too can eat the apple that John bought.
ロンにはジョンが買ったりんごが食べられる。
Speaking of Ron, he only can eat the apple that John bought.

The first one goes smoothly, I understand easily, no problem with identifying relatives and all.
The second sounds harder somehow. But isn't the second sentence the opposite of the first?
So my question is.
Isn't this really a simple thing?
While English marks similarity and plurality with "too", Japanese has a marker for difference and singularity?
は sounds kind of だけ to me.
Is this wrong?

Also, I sometimes read that it defines the scope for the sentence. Can someone elaborate on this too?

Answer 1

ロンはジョンが買ったりんごを食べた。
Speaking of Ron, only he ate the apple that John bought.

No, this Japanese sentence does not imply Ron is the only person who ate the apple. This sentence means a very simple thing: "Ron ate the apple John bought", regardless of whether someone else did the same thing. You need to use the particle だけ/のみ to say "only".

In other words, you can safely say "今日は歩かないし、明日も歩かない。".

は implies peculiarity and singularity for what it marks.

No. I am aware that some linguists like to explain は as something like a "narrow-the-scope particle", but that does not mean the thing marked with は is the only one. は is used to indicate what you are talking about. I personally like to call this simply as "the topic marker". (Of course は works as a contrast marker, too.)

Moreover, while the particle も somehow "broadens" the scope, it does not do the opposite thing of は. 今日は in 今日は歩かない may narrow the scope from "as broad as possible", but saying 明日も歩かない does not broadens the scope to "as broad as possible (ie. everyday)". It just broadens from "just today" to "today and tomorrow", for example.