Learn English – No, not, and non


Is there a specific rule, or set of rules, that can be followed to know when to use each word? I have noticed that not is usually used with a verb, but I think that there sometimes are exceptions although I can't think of one now.

Best Answer

Not is a negative adverb; no is a negative quantifier; non- is a negative prefix.
Since negation is so important, thousands of idioms use each of these, among other negatives.
Consequently there are lots of exceptions to the general rules below.

  • Non- is not a word, but a part of another word, usually a descriptive adjective:
    non-lethal, non-professional, non-native, non-technical, non-playing
    (The hyphen is optional.) Each of these mean "anything but ..." -- anything that doesn't
    kill you is non-lethal, anything that's not technical is non-technical, etc.
    This meaning contrasts with un- and in-, which refer to opposites instead of complements.

  • No is half of the answer pair Yes/No, shading off vocally into Nah, Nuh-uh, and Uh-uh.
    But it can also quantify and negate any noun phrase:
    Some blade of grass ~ No blade of grass; One who saw it ~ No one who saw it.

  • Not is the general negator for verb phrases, including predicate adjectives and nouns.
    In a verb phrase, not occurs immediately after the first auxiliary verb.
    If there is no auxiliary verb in the verb phrase, Do-Support supplies a form of do.
    Not is contracted whenever possible, with auxiliaries or subjects (especially pronouns):
    He's not interested ~ He isn't interested; She doesn't like it, but not *She not likes it.

Any of these negatives (and many others) can negate a sentence, changing its truth value.
It's easy to switch between them, too; the sentences below all mean the same thing:

  1. They allowed no phone calls.
  2. They didn't allow phone calls.
  3. No one allowed phone calls.
  4. Phone calls weren't allowed.
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