noun + ばかり [exclusivity sense] ambiguity

Question

My understanding of ばかり so far:

After TE form, the meaning is unambiguous as it applies to the verb, e.g.:

本を読んでばかりいる。Do nothing but read books.

However, placed after the noun

本ばかりを読む

The meaning is left ambiguous as it could mean

1. read books only (i.e. nothing else, not magazines, not brochures etc., no implication on how much time the person spends actually reading.)

Alternatively, same as before

2. ONLY read books (i.e. do nothing else BUT read, no implication on the actual material).

However, in another example from a grammar book:

ジョンはビールばかり飲んでいる

It's listed as "John is drinking beer the whole time (he doesn't do anything else)."

I'm not sure whether the meaning is left ambiguous here with this particular translation picked arbitrarily (which would confirm my previous understanding) or one-way only (which would oppose it, to some degree).

Answer 1

本ばかり読む is basically "read books only", but it actually means "only read books" too, as you said. ジョンはビールばかり飲んでいる is the same, it can also mean he may do something besides drinking beer. It's ambiguous in that sense.

Answer 2

Try looking at it this way:

[thing/action] + ばかり

This typically means "[thing/action] only".

You can add more structure to that sentence. But if you fill in the blank with a thing or action of your choice, it typically means that you are doing "that thing/action only".

Take your example with John and the beer:

ジョンは　[ビール]　ばかり　飲んでいる。　John is drinking only [beer].

This could describe a 飲み放題 situation where John has a wide variety of drinks to choose from, but he chooses to only drink beer.

Compare with a related situation using the other sentence structure you mentioned:

ジョンは　[ビールを飲んで]　ばかり　いる。　John is only [drinking beer].

This situation could describe a party at an 居酒屋 where there are a lot of people hanging out, talking, eating, drinking. But John spends the whole night drinking beer and refrains from eating or talking to anyone.

The translation I gave in the second example is not the best, but it remains consistent with the formula used in the first example. A better translation would be, "John is just drinking beer," or, "John spends the whole night just drinking beer."