Are 「〜のは欲しい」 and 「〜のは出来る」 valid alternatives to 「〜たい」and 「られる」?


Are 「〜のは欲しい」 and 「〜のは出来る」 valid alternatives to 「〜たい」and 「られる」conjugations for
desire and potential form? If so, what's the difference?

Examples: If 見れる means "can see," does 見るのは出来る mean the same? If so, is there
a difference in nuance?




No, 見るのはできる is not a valid alternative. However, you can say 見ることができる is, and
it's an alternative form. _A Dictionary of Basic Japanese Grammar_ , page 201
says this about the difference:

> 【Related Expression】
>
> A shorter potential form of verb, i.e., _rareru_ ² can replace the longer
> potential form _koto ga dekiru_ without a change in basic meaning. Thus,
> Examples (a), (b) and (c) can be rewritten as [1], [2] and [3],
> respectively.
>
> [1] 新幹線に乗れば大阪まで三時間で **行ける** 。  
>  _Shinkansen ni noreba Ōsaka made sanjikan de **ikeru**._  
>  [2] 小田は六つの時バッハが/を **弾けた** 。  
>  _Oda wa muttsu no toki Bahha ga / o **hiketa**._  
>  [3] ジョンソンさんは日本語で手紙が **書ける** 。  
>  _Jonson-san wa nihongo de tegami ga **kakeru**._
>
> Basically, the difference between the shorter and the longer potential form
> is one of style; namely, the shorter version is more colloquial and less
> formal than the longer one.

Note that は here is incorrect.

As for 欲しい, this is also wrong. The only similar construction would be using
ほしい as a auxiliary, like so:

> 魚を食べてほしい

But this means a completely different thing; it acts as a request for someone
else to eat fish. Note that this request is inappropriate if the listener is a
higher status than you.

欲しい as a non-auxiliary is only used when you want something, as in:

> ぬいぐるみがほしい  
>  "I want a stuffed animal"

たい is the only appropriate construction for expressing the desire to take an
action.

