What holding costs you
The belief underneath the whole habit is that holding is free. The argument ends eventually, everyone moves on, and nothing's been spent. This chapter adds up the tab, and I'd like you to read it against the marks you made in chapter 1.
The first item is the evening. Every hold is an argument that ran longer than it needed to, and the time after it is worse than it would have been. The silent mile. The dinner where you're both being careful. The hour after the group chat where you keep checking. Holding doesn't end an argument. It extends one, and then it extends the recovery.
The second is the second argument. Chapter 9 described how the line, once it's lost its reasons, goes looking for a principle to stand on. That argument doesn't end when the evening does. It's there next time, as "you always have to be right" and "you never let anything go," and each hold adds to it. Some of the things you're arguing about this year are the second arguments from things you held three years ago.
The third is the slide's bill. If you took the slide instead of holding, it comes due later, in the "I never said that" conversations, where you're now arguing about what you said rather than whether it was true. Those are worse than the original, because there's no roadworks to check.
The fourth is the effort. Holding is work. You have to keep producing defences for a thing you don't believe, and each one has to be checked against the last one for consistency, and you have to manage your face. That's attention, taken from whatever else was going on. It's not much per argument. It's a lot per year.
The fifth is the quietest and, I think, the largest. People stop telling you when you're wrong. Not out of spite. Out of economy. If correcting you costs them twenty minutes and a bad evening, they'll do it less, and then they'll stop, and you'll be wrong about more things for longer, with nobody to say so. Porter and Schumann's work in chapter 15 found that people who recognise the limits of what they know are more open to the other side's reasons. The reverse is that people who hold don't get offered reasons any more. The habit that's meant to protect your standing ends up protecting your errors.