T-Rex: In conversations, speakers generally try to make helpful contributions, and listeners generally assume that this is the case! This is called the "cooperative principle", and philosopher Paul Grice proposed it! He's dead now.

T-Rex: It's useful because it allows inferred meanings!

T-Rex: We can be at a party and someone can say "Where's Utahraptor?" and I can say "He's sick" and they understand that he's not here BECAUSE he's sick. Inferred meaning! If they don't assume I'm cooperating then I'm just offering non-relevant information, on the same level as if I answered "Utahraptor's got shufflepants." and then clarified "They're pants that shuffle when he walks."

Utahraptor: But maybe I'm not at the party BECAUSE of my shufflepants!
T-Rex: See?

T-Rex: The cooperative principle is so ingrained that even when I say non sequiturs, you're looking for a way to read it under the assumption I'm cooperating.
Utahraptor: So I should assume that you're a disingenuous and unhelpful jerk.
T-Rex: Yes!

T-Rex: In this example, I mean. In real life I am a charmer, of course!! Hah! I am loveable and trustworthy and good at conversations!
T-Rex: ...
T-Rex: I've had FIVE girlfriends, Utahraptor.