"I'll just check once more"

The number is up and you don't believe it, so you step off and step on again. Or you take the top off, or you shift your feet, or you go to the loo and come back. The second number is different, sometimes by a lot for something that took forty seconds, and if it's kinder you take it and if it's crueller you take the first. Either way you've stood on the scale twice before the kettle, and the third time is always available.

The second step can't settle anything, and it helps to know exactly why. Bathroom scales aren't precise to the hundred grams they display, and they read differently if you're placed differently on the platform, if the platform is on a different bit of floor, if you've moved, breathed out, or lost a little water in the loo. None of those is fat. So the two readings are two samples of the same noise, and choosing between them is choosing which noise you'd like to believe. The second step feels like checking. It's actually a second roll of the same dice.

You've checked already, in this series, is about checking the door, the oven and the email, and one of the things it says is that a second check makes you less sure rather than more, because the second look competes with the first in memory and neither wins. The scale is a cleaner case than the door, because the second reading really is different, and so the uncertainty has something to feed on. You now have two numbers and a reason to want a third.

What the second step is doing, I think, is trying to make the number say something bearable, and the fact that you're doing it is the clearest sign in this book that the number has stopped being information. Nobody rechecks a data point. You recheck a judgement you don't like. If you notice yourself reaching for the second step, that's the moment to notice that you're arguing with water.

The rule, which all three options in chapter 17 share, is one step or none. One reading, written down, and off. If you don't like it, that's allowed, and the dislike goes in the notebook next to the number if you want, and it's still one reading. The second step is the habit telling you it wants a better number. You've stopped taking orders from it.