You don't have to win this one
Why winning seems right
Before I argue with the habit I want to be fair to it, because it isn't stupidity and it isn't cruelty. It's usually a good quality pointed at the wrong target.
Truth matters. You care whether things are so. A person who lets a false thing stand because correcting it is awkward is a person who's chosen comfort over accuracy, and you'd rather not be that.
Letting it go feels like lying. If you know the plumber came on Tuesday and you say "maybe it was Wednesday", you've said a thing you don't believe, to keep the peace, and that sits badly.
Being right is being competent. You remember things. You plan routes. You know the recipe. The fact is a small demonstration that you're a reliable person, and having it overruled by someone who's wrong is a small demotion.
They'll keep being wrong. If you don't correct the plumber's day, they'll say Wednesday to the plumber, and the insurance, and their mother, and it'll be your problem later.
It's the principle. It's not about the plumber. It's about whether what you say is believed, and that matters.
It's not about winning. You'd say this if asked, and mean it. You don't care about winning. You care about it being right, and if they'd just look at the calendar there'd be nothing to argue about.
It's habit, by now. The correction comes out before you've decided to make it, in the tone it's always come out in, and a correction that's been made a thousand times isn't a choice any more. It's a reflex with a phone in its hand.
And you were right. Often. The calendar said Tuesday. You have a record, and the record is good.
And there's the moment itself, which is worth naming as a reason. The fact is stated, the correction is available, and the second between the two is the shortest second in the day. Nobody decides to argue about a plumber. They find themselves three sentences in, with the phone already out, and the deciding happened somewhere before the first sentence, in a place the habit lives and the person doesn't visit.
There are needs under all of this. To be accurate. To be believed. To be seen as competent by the person whose opinion matters most. Not to say things you don't believe. Those are good needs, and the method later in the book meets them better than winning does. What I'll show is that the certainty driving the campaign is the same certainty on the other side of the table, that both of you are inside a spiral neither of you started, that dropping a fact isn't lying, and that the record of being right is a record of evenings.