"I've earned it"

This is the sentence, and it's the one to start with because it's the most convincing. It's true, too, in its way. You did work. The day did take something out of you. Something at the end of it is a reasonable thing to want. The trouble isn't that the sentence is false. It's when it arrives.

Cat Taylor, Thomas Webb and Paschal Sheeran at Sheffield collected the reasons people give themselves for eating something they'd meant not to, and an earlier book in this series, The biscuit tin, uses their findings about biscuits. Deserving it came first on their list. The point I want from their work is a different one. A justification isn't a judgement made about the day and then acted on. It's a reason that's needed once the hand is already moving, and "I've earned it" is the reason that's always available, because every day contains some effort and effort is what the sentence runs on.

Ran Kivetz and Yuhuang Zheng at Columbia tested this more directly. They found that people justify giving themselves something they'd normally hold back from by two routes, and one of them is entitlement, the sense of having worked hard or done well. When they raised the effort a task took, or told people falsely that they'd done excellently, people chose the indulgent reward over the sensible one more often. The effect was larger in people who felt more guilty about indulging. That last part matters. The earning isn't a sign that you're relaxed about treats. It's what people who feel bad about treats need in order to have one.

Uzma Khan and Ravi Dhar found something similar with virtue rather than effort. Having made a virtuous choice first, people went on to choose the more self-indulgent option, and the effect vanished if the virtuous act could be put down to someone else's pressure. Researchers call this moral licensing. Irene Blanken, Niels van de Ven and Marcel Zeelenberg pooled 91 studies of it, with about seven thousand people, and found a real but modest effect, with the published studies larger than the unpublished ones. So it's not a law. It's a tendency, and it's the tendency the earning depends on.

Here's the thing to notice, and it's my reading rather than the researchers'. A verdict on the day would sometimes come back no. A judge who has never once turned down an application isn't judging. The earning is said on the day you finished the report and on the day you did nothing much, in the same words and with the same confidence, because it isn't measuring the day. It's licensing the treat, and it was always going to. Once you see that, the earning loses its authority without losing its truth. You did earn something. The question is whether the daily is it.