Replacing the conditional with the past subjunctive

Replacing the conditional with the past subjunctive
 

Would it be true to say that the conditional tense may also sometimes be replaced by the past subjuntive, and can often be translated as 'would'?

Or is there a better way to put it? or some specific grammar rule governing this use?

I'm talking about examples like ...

¡Nadie lo creyera!
Nobody would believe it.

Temíamos todos que se precipitara al río.
We all feared that he would fall into the river.

and this one where the governing verb isn't in a past tense

No es sorpresa que Breeanna viniera aquí.
It's no surprise that Breeanna would come here.

Also would these sentences work just as well and be gramatically correct using the conditional?

Thanks in advance for any insight or suggestions.

The answer is 'yes' but I'll let a native speaker say something because I might get it wrong.

I just thought I would comment about terminology. The conditional and subjunctive are not tenses, they are moods. A finite verb has 5 attributes: number (sg.,pl); person (1,2,3); voice (active, passive); tense (present, future, etc.); and mood (indicative, subjunctive, imperative, interrogative and conditional). You describe a verb exactly by specifying a combination of these attributes. :)

It's a matter of case by case.

"¡Nadie lo creyera!" is unusual in actual language in present or future situation, whether it works as a conditional or not. Talking about past contexts it can be used with a basic meaning of "nobody believed it!" where subjunctive mood reinforces the "didn't happened" component.

Anyway, actual speakers seldom choose these ways unless there's a need in the speech to defocus that part, as in:

Les dijo que le habían asaltado unos gitanos, y como nadie le creyera, cambió su versión por una que los sustituía por unos cazadores furtivos vestidos de manera inusual.

Temíamos todos que se precipitara al río.
(Wouldn't it be "We all feared that he might/could/would fall in the river", with might or could for an involuntary fall, and would for an intentional action? Spanish doesn't distinguish by merely using subjunctive if context doesn't help)

No es sorpresa que Breeanna viniera aquí
(It's no surprise that Breeana came here -?-. It clearly refers to an action in the past: Breeanna came indeed)

Thanks guys,

@ Perikles - I totally agree about the subjunctive being a mood and I have tried to research whether the conditional is a tense or a mood so your explanation about verbs was great. From what I found I was under the impression that even grammarians can't agree on whether the conditional is a tense or a mood, for example I read this article leaning towards it being classed as a tense:

The Spanish conditional — although semantically it expresses the dependency of one action or proposition upon another — is generally considered a "tense" of the indicative mood, because, syntactically, it can appear in an independent clause.

@ Alex

Thank you, your examples were very helpful. I'm still trying to get my head around how falling in the river could be intentional jeje but I get the rest :)

My mistake, precipitarse means either fall (from a high point, like a cliff or a zeppelin) , throw oneself, or rush (hurry) and the use is semi-formal for throwing oneself and almost-formal for falling from the heights. Precipitarse al vacío is a common fixed expression describing what happens when a person throws him or herself from a window on the 40th floor or an climber loses his grip to a steep rock face and all the safety equipment fails.

That is nonsense to me, because you don't need an indicative to make an independent clause. Ultimately though, the labelling is a matter of choice.

What I got from the quote was that an independent clause would need to have a verb in a certain tense and given that the conditional can appear in an independent clause it would be a tense of the indicative mood.

But as you say it's just a label.

So this model sentence from the daily calendar page, Nunca pensé que esto podría pasar. really should be ...pudiera pasar., right?

I think you're right in this case. But it's confusing because there are other seemingly similar cases in which you use conditional--for example, you would say "Nunca le dije que podría hacerlo." The idea of thinking of indicative versus subjunctive as a mood helps. Indicative mood is something you think has an element of objectivity, truth, or concreteness, so "I never said I would do that"--I never told you something would happen in the future. But "Nunca pensé que esto pudiera pasar" is "I never thought this would happen," indicating doubt (at the time of the first verb) so it's subjunctive. At least--I think so; someone else might be able to elaborate.

Better late than never :)

Nunca pensé que esto pudiera pasar ---> I never thought it could happen -as it did, indeed-

Nunca pensé que esto podría pasar ---> I never thought it could happen -it did happen or maybe it didn't-

That's quite useful for me, too. Thank you :D

También se puede usar el imperfecto de indicativo :

Nunca pensé que esto podía pasar.

Nunca pensé que esto podía pasar ---> I never though it to be possible -as it is- <and not "... it was possible" nor "... it would be possible">

Though we have to be very careful before stretching the use of the verb poder -argued to be a modal verb in Spanish- to ordinary verbs, we have three examples that can be used in the same context with similar meaning, but showing the specific features of every tense which translate not much as nuances but as hints of what's in the speaker's mind:

... pudiera pasar ---> departing from the basic value of Spanish subjunctive (to be an action killer) it shows two facts mutually exclusive: my construe of a reality that doesn't include such possibilities and reality itself which do allow those to happen. Subjunctive allows both matter and anti-matter to coexist, so to speak, and both "realities" to be true at the same time. In that way we are informed that "it did happen indeed" or "it is possible or customary for it to happen" regardless I wasn't aware about that.

... podría pasar ---> departing from the potential value of conditional, it shows a chain of events starting with the denial of a possibility and later that possibility becoming an actual fact -of me becoming aware of my initial misconception-. In that way we are informed of my state of mind in the past.

... podía pasar ---> departing from the imperfective aspect and its characteristic "fuzziness" regarding the beginning and completion of an action, it shows both action happening -what actually happened or happens and my ignorance or disbelief about it- but it avoids the conflict of two mutually excluding realities -what subjunctive accomplishes- by contrasting the perfective and imperfective aspects: the kind of facts implied by that imperfect -without a clear beginning or end for them and then somewhat unrestricted- is shown against the perfective aspect of past simple, that is, it is shown that my original conception has come to an end.

You can see all three phrases may communicate the same situation provided the context contributes with additional elements. For instance "nunca pensé" instead of "no pensé" or "no pensaba" is a very powerful bit that points to my state of mind and not to my practical knowledge.

As you say this can be tricky but I would give a try to pinpoint the usage of the subjunctive, the imperfect indicative and the conditional for this particular construction
Nunca pensé que esto podría pasar

Main clause verb = simple past and the subordinate clause in conditional tense.
The meaning if you are talking about a past action (afterthought) the conditional suits the idea of the afterthought about a past state of mind about a past action (infinitive pasar with podría a Spanish Modal) . If the speaker thinks about this action after an 'accident' the accidente belongs to the realm of no real at the present moment short or long after it happened.
Pudiera ( imperfect past) is also germane since the subjunctive is the mood of no reality, wishes, opinion, etc).

Podía is an imperfect past the action is not finished into the past and if you refer to a past not finished fits the realm of not truth yet.

<<Would it be true to say that the conditional tense may also sometimes be replaced by the past subjuntive, and can often be translated as 'would'?>>
The imperfect subjunctive (-ra) has connotations of past, present and future) We have to recall that the subjuctive mood does not have time clear-cut limits as the indicative mood. And aslo its origiin (imperfect subjunctive) from the Spanish indicative mood, Pluperfect indicative or
antecopreterite (Había comido).

According to context and timing the answer is yes :
Yo comiera más pero no tengo hambre
Yo comería más pero no tengo hambre

<<<Or is there a better way to put it? or some specific grammar rule governing this use?

I'm talking about examples like ...>>>>

¡Nadie lo creyera!
Nobody would believe it.
¡Nadie lo creería!

¡Nadie lo cree!
Nadie lo creerá

Temíamos todos que se precipitara al río.
We all feared that he would fall into the river.

Here temíamos is imperfect indicative the action from the past is not yet finished) it has the sense of durative action therefore non factual yet, the imperfect subjunctive is germane. The conditional usage would give a tint or shade of possibility about something not finished (imperfect indicative or copreterite= temíamos)

and this one where the governing verb isn't in a past tense

<<No es sorpresa que Breeanna viniera aquí.
It's no surprise that Breeanna would come here.>>

No es sorpresa ( Present denial) non factual the subjunctive germane)
No es sorpresa que viniera/venga aquí. The speaker is already in the place. The conditional is future from the past. And the main clause is present.
Also would these sentences work just as well and be gramatically correct using the conditional?
No sería sorpresa que llegara Sue
No será sorpesa que llegue sue
Thanks in advance for any insight or suggestions.