A quantity implicature is a conversational implicature based on an addressee's assumption as to whether the speaker is observing or flouting the conversational maxim of quantity.
If the speaker is assumed to be observing the maxim, then the addressee makes a standard implicature. If the speaker is assumed to be flouting the maxim, then the addressee makes a more non-standard type of implicature.
The utterance Nigel has 14 children commonly implicates ‘Nigel has only 14 children’, even though it would be compatible with Nigel’s having 20 children.
The utterance War is war is itself uninformative; however, depending on its context, it will implicate items such as the following:
- ‘All war is undifferentiated (and thus uniformally unjust).’
- ‘This is the way war is; stop complaining.’