Meaning of 笑えば笑える (and in general of verb + ば + verb + potential)


In _RDG_ I found this sentence:

> 君って普通に笑えば笑えるんだ

said after a very shy and introverted character smiles; I understand that
means something like "So you can smile normally", but I don't understand what
nuances adds the construction ば-potential. I tried looking for it on my
grammars and on the Internet, and I also tried looking here for "ば potential"
and for constructions like that (笑えば笑える, 買えば買える, etc.), but I wasn't able to
find anything about this construction.

What do a construction like that mean? How does it differ from 君って普通に笑えるんだ?




The X+ば+X+potential form is _can X_ with implication that X is rare/difficult
or some reticence on the doer's part.

So 笑えば笑える here is used precisely because of the shyness of the character. The
difference from 君って普通に笑えるんだ? is:

  1. 君って普通に笑えるんだ? Oh you can smile normally
  2. 君って普通に笑えば笑えるんだ Oh, you _do_ smile!

1 is a little odd because (specific illnesses aside) people _can_ smile.

* * *

I think the pattern is productive but not applicable for every verb. 買えば買える is
a little odd to me. X+(よ)うとすれば+X+potential may be more widely usable:
買おうと思えば買える, which would mean _can afford (though the price is substantial =
poses some difficulty to pay)_.

* * *

As commented, there are a bunch of similar phrases like

  * やればできる can do (if one is willing enough)
  * なせばなる can do (if one is willing enough/tries very hard)
  * 知る人ぞ知る some people _do_ know (if it is not super famous).

Another similar pattern is 好きな人は好きな. For example,

  * 好きな人は好きな味

means literally _a taste people who love love_. Here again, there is some
implied 'rarity' and the phrase usually refers to 'love it or hate it' kind of
thing (natto, Dr.Pepper, marmite, etc.).




The X+ば+X+potential form is _can X_ with implication that X is rare/difficult
or some reticence on the doer's part.

So 笑えば笑える here is used precisely because of the shyness of the character. The
difference from 君って普通に笑えるんだ? is:

  1. 君って普通に笑えるんだ? Oh you can smile normally
  2. 君って普通に笑えば笑えるんだ Oh, you _do_ smile!

1 is a little odd because (specific illnesses aside) people _can_ smile.

* * *

I think the pattern is productive but not applicable for every verb. 買えば買える is
a little odd to me. X+(よ)うとすれば+X+potential may be more widely usable:
買おうと思えば買える, which would mean _can afford (though the price is substantial =
poses some difficulty to pay)_.

* * *

As commented, there are a bunch of similar phrases like

  * やればできる can do (if one is willing enough)
  * なせばなる can do (if one is willing enough/tries very hard)
  * 知る人ぞ知る some people _do_ know (if it is not super famous).

Another similar pattern is 好きな人は好きな. For example,

  * 好きな人は好きな味

means literally _a taste people who love love_. Here again, there is some
implied 'rarity' and the phrase usually refers to 'love it or hate it' kind of
thing (natto, Dr.Pepper, marmite, etc.).

