Use of subjunctive

Question

Present subjunctive or subjunctive in general is used to express doubt. Even though this has been explicitly stated on my textbook, there still came times when I found some example sentences of subjunctive confusing.

No pensamos que tú tengas razón.

Parece que va a nevar

No pensamos, to me, introduces a sense of certainty. Err...actually, I am not too sure, but these sentences are correct just that I don't understand why they are written this way.

Also, it looks like, looks like nothing like a indicative sentence.

Afterall, my question is why are written like such?

And what are a effective way to identify subjunctive sentences?

Answer 1

An effective way to identify a subjunctive sentence is via its conjugation. Identifying when you need to use it is much more complex, at times obligatory, at others verboten, and of course with an occasion for it to be more or less optional based on intended meaning and a very complex topic.

In your examples, the answers are straightforward and fall in the obligatorily indicative or subjunctive category.

Specifically, what is in question is probability. Is what is contained in the subordinate (or dependent) clause guaranteed to be a part of reality (caveat: in the mind of the speaker in the superordinate clause? Looking at your sentences we get:

• No pensamos que tú [tener] razón.
  The question becomes whether tú [tener] razón is 100% guaranteed a part of our (since nosotros) thoughts/reality. Because we do not think it, it is certainly not a part of our reality, and therefore, when subordinated, the clause goes in subjunctive. No pensamos does introduce certainty: the certainty of it not being real, ergo subjunctive.

• Parece que va a nevar
  While the translation "it seems" might imply doubt, by virtue of it seeming so, it forms a part of the reality. Parece is impersonal, so we don't need to associate it with anyone in particular, it seems it, and therefore it forms a part of reality (within the context of the superordinate clause). So when looking at [ir] a nevar, since it forms part of the reality, we use indicative. If we had said no parece, it would not be considered a part of reality, and would be subjunctive.

Answer 2

Questions about subjunctive mood are rarely simple or quick. I found that better understanding the English subjunctive goes a long way to understanding the nuance presented by subjunctive mood in Spanish. Read http://en.wikipedia.org/wiki/English_subjunctive Examples:

I insist (that) he leave (not 'leaves') now.
We asked that it be (not 'was') done yesterday.
I braked in order that the car stay (not 'stays') on the road.

Note that if you don't use subjunctive mood, the English sentences sound awkward, such as that spoken by a very young child.

Also note that in English, as in Spanish, the subjunctive is used when there's influence, or a hypothetical phrase, as in my examples.