Yesterday, when I was purchasing a take-away tub of yummy gnocchi from a local shop for my lunch, the person serving me undercharged me. Question number one for you is this: when you are undercharged, and you know it, do you consider it fair to take advantage of the error in your favour? Is it a matter of degree? If the error were trivial, would you let it slip by, but raise it as an issue if it were substantial (for some values of "trivial" and "substantial")?

In order to keep the question relatively culture-neutral, let me describe my transaction in Standard Currency Units (SCUs). Think of these as the smallest unit of currency normally significant in an over-the-counter transaction like this. My tub of nosh was supposed to cost 79 SCU, but I was only charged 70 SCU for it. The difference is slightly greater than 10%. Is this difference "trivial", "substantial", or somewhere in between?

Complicate the matter further: the issuing of change (and thus the final determinant of the amount of the transaction) is usually the point at which the transaction is over and etiquette allows the server to go on to the next customer. Thus, by the time I'd inspected my change and determined that I'd been undercharged, the person serving me had indeed started on a new transaction with a different customer. In order to correct the error now, I would have to wait for the new transaction to complete and then attract her attention, or interrupt the transaction in progress. I wish to be honest and return the 9 SCU I still owe them, but I only have a 10 SCU coin, so further interaction with the server is necessary. Is it worth it for the sake of a measly 9 SCU?

I decide to make an attempt at correcting the error. Perhaps I take this "ethics" and "honesty" thing too seriously. This proves less than trivial on the grounds that my server is totally unaccustomed to this kind of exception processing. She initially misunderstands me, apologising and offering me an additional 20 SCU coin to make up for overcharging me in some way. No doubt the "overcharged" exception is raised rather more often than the "undercharged" exception. After a short explanation, which I was slightly embarrassed do deliver (making a fuss over giving back 9 SCU is probably a bit of an outlier on the cultural bell curve, you see), my server realised her mistake: she had assumed that all their pasta dishes were priced at 70 SCU, whereas the gnocchi was a special case at 79 SCU. She took my 10 SCU coin and replaced it with a 1 SCU coin. All was settled.

In my position, what would you have done? Would your actions have been ethical? Part of my ethical problem in this case was that I was undercharged rather than overcharged. If I am overcharged, then I feel quite at liberty to decide for myself whether I should raise an exception over the matter. If I consider the amount to be trivial, then I may let it pass. In the case of being undercharged, however, I am obliged to make a decision on the part of the shop as to whether the amount is sufficiently trivial to let pass. I don't know the shop owner, and I have no idea what he thinks of this matter, so my safest ethical recourse was to raise the issue.

Ethics is a game without hard rules, but I think that if intent could be judged, I behaved in the most ethical possible manner. That's not to say that my actions were the only ones acceptable from an ethical standpoint. Based on the same intent, I could have acted in a number of ways. I could easily have left the 10 SCU coin on the counter and converted the error to a 1 SCU overcharge, with implicit permission on my part for them to "keep the change". Similarly, if I'd known for a fact that the mere act of processing my exception was going to cost them more than the 9 SCU they stood to gain, I would have had no qualms about keeping the money on the grounds that it would be acting in both our financial interests to do so. All of these options would have been hard to fault from an ethical standpoint, so far as I can tell.

On a tenuously related matter, I purchased a "regular flat white" coffee from another shop later in the day. That cost 59 SCU, which they charged correctly. They also have a customer incentive scheme whereby you get a free regular-sized drink for every ten paid purchases. Given the variation in price for regular-sized drinks, the effective discount offered by this card could be as much as 13%, which is not bad. And unlike certain previous occasions, there was no froth on top this time.