Because they contain double negatives, the above English sentences are considered substandard (although, of course, people often talk like that in real life). But there's no such prohibition in Spanish. In fact, in many cases, use of double negatives is required. Even triple negatives are possible.
Grammarians may tell you that English doesn't use double negatives because the two negatives contradict each other and make a positive. (In other words, "I don't know nobody" is the same as saying "I know somebody.") But negatives aren't viewed that way in Spanish — the negatives are seen as reinforcing rather than contradicting each other. Although sometimes the second negative is used to make a stronger statement just as it is in substandard English, in most cases it is merely part of the grammatic structure of the sentence.
In Spanish, the most common negative terms in addition to no (no, not) are apenas (barely, scarcely, hardly), jamás (never), nadie (nobody), ni (neither, not), ninguno (none, no), ni siquiera (not even), nunca (never), and tampoco (not even, nor, neither). Most of these terms in Spanish have a corresponding affirmative term: algo (something), alguien (somebody), alguno (some), siempre (always), también (also), and siquiera (at least).
General rule: As a general rule, a sentence can't include both affirmative and negative terms; where one element of a sentence (subject, verb, object) includes a negative term, so should the other elements that need other such terms. Also, one and only one negative term normally is used before the verb.
By following these rules, it is possible to have one, two or three negatives in a sentence, as in the following examples:
- Apenas come. She barely eats.
- Apenas come nada. She barely eats anything.
- No tengo ninguno. I don't have any.
- Nadie sabe eso. Nobody knows that.
- Jamás fumo. I never smoke.
- Tampoco comió. She didn't eat either.
- Tampoco comió nada. She didn't eat anything either.
- No habló. He didn't speak.
- No dijo nada. He said nothing.
- No le dijo nada a nadie. He didn't say anything to anybody.
- No compro ninguno. I'm not buying any.
- Nunca le compra nada a nadie. She never buys anything for anybody.
- No come ni siquiera pan. He doesn't even eat bread.
- Ni siquiera come pan. He doesn't even eat bread.
Note also that various translations to English are possible. Tampoco comió could be translated not only as "she didn't eat either" but also as "neither did she eat."
When a verb is used with a negative term, it isn't always necessary to use a negative term after the verb. For example, "No tengo amigos" (I don't have friends) is grammatically acceptable. What you shouldn't do, though, is use an affirmative term for emphasis. If you want to say "I don't have any friends," use a negative term after the verb: No tengo ningún amigo.
Other uses of double negativesThere are at least two other cases where a double negative is used for added emphasis:
Nada as an adverb: When used as an adverb in a negative sentence, nada usually can be translated as "at all." No ayuda nada, he doesn't help at all. No usa nada los ordenadores, he doesn't use computers at all.
Nunca jamás: When these two negatives meaning "never" are used together, they reinforce each other.
- Nunca jamás vuelo. I never, ever fly.
- Dijo el cuervo, "nunca jamás". Quoth the raven, "nevermore."
Have a question or comment? See the blog post for this lesson: Can't get no satisfaction.