Double Negative
He visto unas frases como:
No es nada.
No quiero nada.
Ella no pudo darle dinero a ninguno.
En inglés, "I don't want nothing" no es correcto, pero ¿es correcto en español?
Además, ¿"no quiero nada", y "no quiero algo", y "quiero nada" significan lo mismo?
Gracias 
6 Answers
Yes, double negatives are used in Spanish. In practice, negative statements begin with a negative before the verb. So you can't say
Yo quiero nada
but
No quiero nada.
But you can also say, no quiero ir al cine... just a single negative. But the negative word still procedes the verb. You can also say
Ningúna persona quiero ir, where there is also a single negative indicator, but again it precedes the verb.
The reason why Spanish has these "double negative" constructions is due to the fact that the words "nada", "nadie"... were not negative originally! A sentence like "No quiero nada" (I wrote it in modern Spanish for simplification) was, literally, "No want anything", so in the past there was no double negative whatsoever. It is not difficult to find Medieval sentences like "Nadie no vino" (= One not came, i.e. No one came). Later, "nada" and similar words changed their meaning due to the fact that they appeared most of the time in (normal) negative sentences, so this association turned them into negative words, but the construction was kept as it was in the first place, with the "no" at the beginning of the sentence. In other words, its syntax remain the same, but the words change their meaning.
This type of changes are very common in languages as they evolve.
I also felt double negatives were odd, at first. Then I realized that I had been using double negatives in my native Hungarian, and not realized it. There, I feel like the sense of two negatives is not a compounding logical meaning as we sense in English. Rather, it feels more like a consistency of mood, just as you would match gender or plurality in adjectives.
With practice, you will get used to it.
This is yet one more reason to try to think in Spanish, rather than think in word-for-word translation. Thinking in translation slows you down, gets in the way, and gets you into trouble. Buena suerte.
Además, ¿"no quiero nada", y "no quiero algo", y "quiero nada" significan lo mismo?
No es lo mismo porque sólo la primera frase es correcta.
"Nada" indica negativo, entonces va con "no."
"Algo" indica positivo, entonces va con verbos sin "no."
"Quiero" sin "no" indica positivo, entonces no se puede colocar con "nada."
Yes, double negatives are common in Spanish. Here's a link to the lesson that includes double negatives.
Nada - our dictionary gives this.
- nothing (en general) ; (en negativas) anything
No tengo nada = I don't have anyhing
