Remarks on writing dialogues (or the academic semester is over and I'm already bored)
Each character has to sound differently, yes, but beneath all that there's the mechanics of dialogue itself: meaning, the way information is structured.
As a writer, you work with this on two layers. There's the information you want to communicate to the reader and there's the information you want the characters to communicate to each other, all while avoiding infodumping and making sure the interaction feels like real people talking.
This is where the notion of presupposition becomes useful.
Very roughly, a presupposition is information that a speaker treats as already known or already accepted in a given context. When a character says, "You haven't been the same since dad's funeral" the sentence is not really about the funeral. It's about someone's behavior. Yet the existence of dad, his death, the funeral, and its emotional consequences are all taken for granted rather than explicitly stated.
Real conversations work like this all the time. People rarely explain everything they know. They speak from a background of shared assumptions, and listeners reconstruct the missing pieces. Readers do the same thing (the much-discussed "subtext" often emerges from that process; there's much more to say about this, but that's a topic for another post).
Thinking in terms of presuppositions helps you devise different ways of managing information.
Sometimes the characters know more than the reader. That's where presuppositions become a tool for exposition, allowing information to emerge naturally instead of being explained.
Sometimes the characters come to the conversation with different sets of assumptions. That's where (failed) presuppositions become a powerful tool for creating meaningful misunderstandings.
Sometimes the reader knows more than one or both characters. That's where presuppositions become a tool for dramatic irony, because the reader interprets the same utterance differently from the people having the conversation.
Knowing all this, it can be useful to map the distribution of information before writing a dialogue (or while revising it).
What does each character know?
What does the reader know?
And, more importantly, where do you want each of them to be by the end of the scene?
Once you have that picture, you can manage presuppositions to choose what information remains in the background, what information becomes visible, what assumptions are shared, challenged, or revealed to be false.
In a sense, this is exactly what real people do in conversation, usually without realizing it. We constantly make assumptions about what our interlocutors already know and shape our utterances accordingly to our goals.
Dialogues in fiction (should) work exactly the same way!
(on a final note: AI are notoriously bad at tracking presuppositions and shared assumptions, so fuck AI. Go write your own flawless dialogues with that beautiful brain of yours 💜)
