puedas vs. puedes?

Question

When do you use puedas (subjunctive) and when do you use puedes (indicative)?

I know its right to say "me puedes dar una cerveza" - but shouldn't requests be subjunctive?

Answer 1

Poder is like any other verb. It can be used in the indicative or subjunctive-- however there must be what we call a "trigger" which calls for the subjunctive. Some impersonal expressions "trigger" the subjunctive.

Es necesario que una mujer pueda pasar varias pruebas antes de ser aceptada para el combate en el ejercito.

Sometimes certain prepositional phrases will trigger the subjunctive. "Haz la tarea en cuanto puedas

In your sentence " "¿me puedes dar una cerveza?" There is no "trigger" It just a question in the indicative.

I have written one article on the subjunctive (link to article on subjunctive)

I am planning to do a follow up. It's about half finished. However the article referenced here will tell you all about "triggers" and what "subjunctive means"

It is not a simple subject, but I have tried to make it as understandable as possible.

In the chart are some simpler uses of the subjunctive with a trigger in the first clause and the subjunctive in the second. Buena Suerte.

Answer 2

http://users.ipfw.edu/jehle/courses/PERSUAD1.HTM

Read the entire thing (the link above), if you really want when to use subjunctive as a whole.

For asking for something:

Use of the subjunctive in independent clauses. As already mentioned, the subjunctive is seldom used in main clauses, but there are a few exceptions:

1. The past subjunctive may be used replace the conditional of the verbs poder, querer, and deber to make a request/suggestion more gentle or deferential.

(Yo) quisiera pedirte un favor. I'd like to ask you a favor.

Debieras practicar un poco más. You should practice a little more.

¿Pudieran Uds. darme otros ejemplos? Could you give me some other examples?

So if you were to put poder in subjunctive for a request it would be past not present. If I remember what I have been told by native speakers, in real life doing this with poder or deber is antiquated or literary and they don’t like it.

It is done with quisiera/querer in my experience- but it is only tolerated in Latin America and I think people from Spain think even that is bad grammar and would not put up with it. My experience with using it is in Mexico only, without issue (not that they always tell me when I sound stupid).

Much better for poder, if you want to soften it, to use conditional: Me podrías dar una cerveza. Could you give me a beer. Might also think about whether to use usted instead of tú if the situation calls for that.

This is my opinion please wait for other opinions.

Especially as there are definitely regional preferences with this.