If I asked what you did yesterday, what would you say? Likely, you’d give me a few of the highlights. You wouldn’t give me an hour by hour account of every tiny detail. But why not? Surely that would be thorough? Helpful even?

Paul Grice observed that in every conversation there are certain “maxims” that govern how to communicate. Collectively, they’re often known as his “Cooperative Principle”.

Conversations are not just using sounds (“phonemes”) or letters (“graphemes”) to represent some concept or object. Things like tone, body language and situational context are needed to define what a word or phrase means. This complex area of linguistics is called “pragmatics”.

Grice’s conversational maxims are examples of pragmatics. They are the rules that all participants sign up to, and when we “flout” them (as Grice calls it), it’s often done for comedic reasons. So, what are these maxims?

1) Quality
We assume that most people, most of the time, tell the truth. If someone lies it would have to have some extraordinary reason.
2) Quantity
We give as much information as required by that context. If someone asks, “Who was Napoleon?”, you don’t start with, “well, he was born in Corsica in August, 1769, an unusually warm month…” before going into a 5-hour monologue.
3) Relevance
We only give information that’s needed. Imagine I say, “this is my friend, James, who’s not murdered anyone for 5 years now”. However true this is, you’d assume my including it made it relevant in some way.
4) Manner
*How* we say things matters. This often means we have to read between the lines. If you ask how my holiday was, and I say “well, it was certainly memorable”, you’ll know what I mean.

These rules work to form the “implicature” of a language, which means what is implied or suggested. Sometimes a deceitful speaker might mislead by exploiting these. So, if your mum says, “do you know who ate the cake?!”, and you say “well, I saw Timmy in the kitchen earlier” you’re using implicature to frame Timmy.

So, now you know the rules of conversation, you can use them as you see fit. You could flaunt and invert them to hilarious ends, or you could mislead and misdirect. Quite the weapon.