The Imperfect Subjunctive

[Zahara]

I'm currently studying the imperfect subjunctive. I understand that there are two alternate endings (-ra, and -se), and I would like to know which one is the more prominent form, and the general usage of one or the other. I apologise if this has been asked before.

Thanks in advance for any help.

[Perikles]

I am repeatedly told that the two forms are totally interchangeable. Maybe there are stylistic variations, but I'll let others deal with that.

[Zahara]

Like perfect synonyms? That's interesting.

[wrholt]

According to some grammars, the -se form historically is the past subjunctive, while the -ra form was an indicative tense whose use has shifted over the centuries to be an equivalent of the -se form as a past subjunctive.*

(*Edit: Perikles rightly points out that I recalled the historical details incorrectly.)

Today as subjunctives the two forms are interchangeable. However, according to some grammars the -ra form is more common everywhere, continues to grow in popularity, and in some regions is used almost exclusively.

Some grammars claim that the -ra form has a few indicative uses that it does not share with the -se form.
1. In some writing styles the -ra form may substitute for the indicative pluperfect: for example, "el hombre que ella conociera años antes" = "the man that she had known years before" (instead of "que había conocido").
2. Sometimes with "haber" the -ra form replaces the conditional: "hubiera sido mejor" = "habría sido mejor" = "it would have been better".
3. In a few set phrases.

Also, when making requests or invitations using "poder" or "querer", it is common to soften the request by replacing the simple present with either the -ra form or the conditional. The -se form is not used in this way.

[Perikles]

Originally Posted by wrholt

According to some grammars, the -se form historically is the past subjunctive, while the -ra form was an indicative tense whose use has shifted over the centuries to be an equivalent of the -se form as a past subjunctive.

Not that it matters really, but the two forms are derived from the Latin imperfect and pluperfect subjunctives, both of which take on the imperfect in Spanish. See here for example.

[pjt33]

Originally Posted by Zahara

I would like to know which one is the more prominent form

It's for tasks like this that linguists create corpora. The main corpus for Spanish which I know is CORDE; comparing estuviese vs estuviera from 1950-2012 I get 422 cases vs 1117. So there the -ra form seems to be preferred.

You may want to repeat the search over a number of common verbs and applying restrictions in various of the metadata to get a more complete picture. Just be careful with ser, because fuera has another meaning...

[aleCcowaN]

-ra form more used in most of América (some 70% of total speakers), -se form more used in Southern Spain (some 4% of total speakers). The rest vacillates. Everybody knows both of them and use them to avoid monotony. A great deal of educated speakers easily recognize the special uses describe by wrholt and have troubles to instantly match the versions using -se ending.

[Gala]

I'd say to focus primarily on the -ra form, but still learn to recognize/understand the -se.