In 1975 a philosopher of language named H. Paul Grice in his essay “Logic and Conversation” introduced the cooperative principle. The cooperative principle is based on the observation that people involved in a conversation are cooperating with each other in order to promote the conversation and to convey meaning. This principle was expressed by a set of four maxims, known as Grice’s Maxims:
Maxim of Quality
Do not say what you believe to be false.
Do not say that for which you lack adequate evidence.
Maxim of Quantity
Make your contribution as informative as is required.
Do not make your contribution more informative than is required.
Maxim of Relevance
Be relevant to the matter in hand.
Maxim of Manner
Be clear, brief, orderly, and unambiguous.
Violating the maxims unintentionally
Did you watch the movie Casablanca?
With this question as context, the following replies are likely to frustrate and confuse the conversation partner:
Violating the Maxim of Quality:
No (when they did see it)
Violating the Maxim of Quantity:
I saw the movie on February 12 at 5pm Pacific Standard Time in my aunt Sophie’s house, 22 Oak street, on my 15 inch Mac Book Pro.
Violating the Maxim of Relevance:
Did you know that ‘Casa Blanca’ means ‘white house’ in Spanish?
Violating the Maxim of Manner:
I’ve seen all kind of movies.
Flouting the maxims
Grice’s maxims are unstated assumptions people have in conversations.
The interesting insight is not that we actually follow these maxims at all time – but that when we don’t, people, who assume we are being cooperative in the conversation, will look for other meanings that could be implied. A cooperative speaker can intentionally disobey a maxim, as long as the context provides enough indicators for the hearer to notice it. An uncooperative speaker, who disregards a maxim meaninglessly, will cause confusion and distress to the hearer.
^ Flouting the Maxim of Quality
Ian is an incredible ice-skater
When the maxim of quality is obeyed, this is a positive evaluation of Ian’s talent. If this is said watching Ian stumble and fall on the ice, the maxim of quality is flouted; the speaker communicates the complete opposite of the literal interpretation of the utterance. This is called sarcasm.
Well, what a surprise! (when you expected something to happen, especially after warning someone about it)
You are my sunshine
This cannot be categorically true. Metaphors is another reason to flout the Quality maxim.
^ Flouting the Maxim of Quantity
I hope you brought the snacks and juice.
Ah, I brought the snacks.
Bob gives less information than is required. This communicates that Bob didn’t bring the juice.
Of course I brought the snacks. Why would I fail to bring the snacks. Bringing the snacks was my first priority. Who would forget a thing like that.
This information overflow suggests irony.
Where are you going?
When will you be back?
Daniel’s answers are not as informative as the answers Dina is looking for. It is usually assumed people will be as informative as required. When not enough is said, then we assume the speaker simply doesn’t know, or that he doesn’t want to convey the information.
I may bring the book back next week.
This also flouts the quantity maxim. It implies I might fail to to bring the book back next week. If I was firm in my intent, I would have said so.
^ Flouting the Maxim of Relevance
Lets play tennis.
It is raining today.
Apparently Sally prefers not to play tennis while it’s raining.
How did you score on the Math exam?
Lets play tennis.
The message is “I rather not talk about it”.
Did you like my book?
The illustrations are very colorful.
Steve is violating the Relevance maxim. Perhaps he didn’t like the book.
Does the boss really expect you to do all this work in one week?
Let’s go get some coffee.
In order to preserve the cooperation principle, Lily has to assume there’s some reason Lisa makes an irrelevant remark. Perhaps the boss is nearby.
Would you like a slice of the chocolate cake?
Is the pope Catholic?
Bart would love to have a slice, and will always accept offers of chocolate cakes.
What on earth has happened to the roast beef?
The dog is looking very happy. 
^ Flouting the Maxim of Manner
I hear you went to the opera last night; how was the lead singer?
The singer produced a series of sounds corresponding closely to the score of an aria from ‘Rigoletto’. 
With the use of prolixity, Chad is flouting the maxim of Manner; this implies the singer was not very good.
Grice’s Maxims are not rules. They are baseline conventions. Flouting them is adding a layer of meaning, not “breaking a rule”. This means that a person isn’t “doing something wrong” when he responds to “How are you doing today?” with “It’s raining”. It means he is actually giving an even more meaningful statement. 
You can think of Grice’s Maxims as rules for the hearer, more than rules for the speaker. If something looks like it violates a particular maxim, assume that the speaker has some good reason to do so and try to figure out what additional meaning the speaker is trying to add.
Next section: Politeness Strategies.
Pragmatics. George Yule. Oxford University Press, 1996.
 Pragmatics. Stephen C. Levinson. Cambridge Textbooks in Linguistics, 1983.
 Grice’s conversational maxims according to Wug Life