I won't not use no double negatives.

[trolley]

Sometimes, I come across a phrase that I have used my whole life without ever really breaking it down and thinking about what I am actually saying. The other day I responded to a friend with "not on my watch, you won't". I knew what I meant and he knew what I meant but he just looked at me and smiled, "Then I will?"

[Erik_Kowal]

Sometimes, I come across a phrase that I have used my whole life without ever really breaking it down and thinking about what I am actually saying. The other day I responded to a friend with "not on my watch, you won't". I knew what I meant and he knew what I meant but he just looked at me and smiled, "Then I will?"

I don't consider that to be a genuine double negative. In my opinion, it resolves as "You won't [do X] — not on my watch!" This amounts to a rhetorical intensification-by-repetition of the basic point, which is a different animal altogether.

Your sassy friend, on the other hand, was incorrectly analysing it as "You won't not [do X] on my watch", hence your shared but mistaken perception of a double negative.

[trolley]

Ah, "You won't [do X] — not on my watch!" = "You won't [do X] on my watch, with a little dash of emphasis.

[tony h]

I agree with Erik that it isn't a double negative. The "not on my watch" seems to be a simple modifier to "you won't" to give the context to which the "you won't" applies.

In my view other similar phrases include:
- not at work, you won't.
- not while driving, you won't.
- not while you just sit about thinking about questions on WordWizard, you won't.

What puzzles me is what part does the "not" play as it seems that all the phrases would mean exactly the same thing without the "not". eg "not on my watch, you won't" is equivalent to "on my watch, you won't"!

The "not" does seem to provide some additional emphasis but quite how grammatically this may be explained ... thoughts die out.

[Bobinwales]

Rightly or wrongly, I see an ellipsis. So, "Not on my watch... you won't", has the two phrases separated.
I do realise that I might be utterly wrong.

[Phil White]

What puzzles me is what part does the "not" play as it seems that all the phrases would mean exactly the same thing without the "not". eg "not on my watch, you won't" is equivalent to "on my watch, you won't"!

Nice spot, Tony. I got to the same place, which rather destroyed the argument I was going to make.

Yes. Everyone else has said it is an emphasizer, and I shall chime in with my clapper of agreement. But Tony is right to point out that the construction also works without the "not", although it is rarer and loses power.

The only explanation I can proffer as to why we do not sense the construction as a double negative is as follows:
Take this example:

• "I'm going to the pub." "Not if you want any supper you're not."

It seems to me that we understand the first negative as negating the idea of having or wanting supper and the second negative as negating the idea of going down the pub. It's a bit of a long shot, but the best I can do.

I shall refrain from my normal diatribe on the gibberish that is talked about double negatives. They are not unusual (sic) and they bring colour to our lives. There wouldn't be no blues without them. If they're good enough for Muddy Waters, they're good enough for me. 'Cos I can't get no grindin' neither.