1

As English is not my native language, I have a trouble to find the correct way to express the following:

Two negations are equivalent to an affirmation

properly.

This is how it translates from my native language (Greek) if it is translated word by word: "δύο αρνήσεις ισοδυναμούν με μία κατάφαση", and it does not sound good to me.

Is there a standard English expression (an appropriate cliché, for example) with this meaning?

UPDATE. Let me give an example of what this expression really means:

"There is NO student in this classroom who DOES NOT HAVE a pencil."

is logically equivalent to:

"Every student is this classroom HAS a pencil"

So the first sentence has two negations - a negation of a negation - while the second one has affirmative nature.

Improve this question
6
  • 1
    Two wrongs don't make a right, but three lefts do.
    – SF.
    Commented Feb 4, 2014 at 11:59
  • Two Wrights make an airplane.
    – David Schwartz
    Commented Feb 4, 2014 at 12:37
  • Every student has at least ONE pencil
    – mplungjan
    Commented Feb 4, 2014 at 13:17
  • Grammatically, your example sentence makes sense, but stylistically I was taught to avoid it because it can lead to awkward constructions. Instead, either state things in the positive (as in your second example), or use a word that expresses the negative, eg, No student lacks a pencil.
    – James Kingsbery
    Commented Feb 4, 2014 at 14:51
  • 1
    It would help for you to provide more context about how you want to use this expression. English teachers give students a common admonition: "Don't use double negatives!" If you're a math teacher you could make a joke that math is better than english because you can use double negatives all you want - as long as you can keep it straight that what you're saying is what you think you're saying and what others think your saying is what you're really saying.
    – CoolHandLouis
    Commented Feb 4, 2014 at 15:27

2 Answers 2

Reset to default
5

Two negatives make a positive. Minus times minus is plus. Also, two wrongs (don't) make a right.

Edit to address your update: the term in logic for the situation you describe is double negation. Not to be confused with the linguistic term double negative, where two (or more) negatives might or might not resolve to a positive, depending on language and context.

Improve this answer
1
  • Two wrongs don't make a right, but three lefts do. ;-)
    – TecBrat
    Commented Feb 5, 2014 at 1:32
0

'Two minuses make a plus'. That's how it was explained to me, over fifty years ago!

Improve this answer
1
  • I corrected the title of my question: minus-> minuses.
    – Yiorgos S. Smyrlis
    Commented Feb 4, 2014 at 11:23

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .