When should one not use the verb *Poder*?

Question

I have been using poder in exactly the same way I would use the English meanings can and to be able to. However, as the following equivalent sentences show,poder is sometimes omitted. Whereas in English this omission cannot be done.

No te escucho bien, habla más fuerte. I can't hear you well. Speak louder.

No te oigo bien, habla más alto.

So, my question is, when should one not use poder?

Note

I thought that it would be more intuitive to ask "when not to use..." rather than asking "when to use... or How to use...".(As those might be classed as too broad) However, I don't mind if the title is changes to something more fitting.

Answer 1

You are right that the use of "can" (or "be able to") is more extended in English than "poder" is in Spanish.

I'd say that "poder" can be omitted when the verb in Spanish already suggests an ability. Actually, it does happen that "can" is sometimes redundant in English and can be replaced with the present tense of the main verb:

• I can't understand = I don't understand.

With verbs implying physical perception or some mental process, "poder" would be a little too emphatic in Spanish, meaning something like: Even if I try to, I can't.

• No te oigo.
• No puedo oírte. (Sorry but, no matter how hard I try, I can't hear you.)

(Please notice that, even if its use is extended, "escuchar" is equivalent to "listen to" and involves a voluntary action, so it would be most impolite to tell somebody that you don't want to hear them.)

• No te veo.
• No puedo verte. (It's too dark and, even if I try to make you out, I just can't.)

To express that effort, we can also use other verb phrases like lograr + infinitive / conseguir + infinitive / alcanzar a + infinitive.

• No logro / consigo / alcanzo a verte.
• No logro / consigo / alcanzo a oírte.

Sometimes, instead of "poder" we use "saber", and that is when a specific skill is being dealt with, as in:

• No sé nadar (I can't swim).