1.B and 2.B Common Ground: What a Writer Assumes the Audience Already Grants

No argument can prove everything from scratch. A writer has to start somewhere, and that somewhere is a belief or value she's confident the audience already holds. That shared belief is common ground. Every piece of evidence that comes after it only lands if the reader has already granted the floor underneath. Take away the floor, and the evidence is just noise, true but pointless to that reader.

Mechanically, common ground is the overlap between what the writer believes and what the audience believes, found before the writer asks for anything new. The writer states it early, often in a 'since' or 'because' clause, then builds the actual claim on top of it. The trick is that common ground is about a premise, not the conclusion. Readers can grant the premise completely and still reject where the writer wants to take it. That's what makes it useful as a starting point instead of a concession: it lets the writer argue with people who disagree with her, not just people who already agree.

The risk shows up when a writer assumes a floor that isn't actually there. If a chunk of the audience denies the premise itself, every piece of evidence built on it stops working, because it's answering a question that part of the room isn't asking. The argument then has to drop down a level and defend the premise before it can defend the conclusion. This is why common ground sits next to credibility: a writer who finds real shared ground looks like she understands her audience, and that trust is what lets the rest of the appeals, the logic, the emotion, the evidence, actually work on them.