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Sunday, May 18, 2003

The Toilet Paper Question 

You're using a reasonably well-maintained public restroom and there are two rolls of toilet paper available for use, with differing amounts of paper left on each roll. Which one should you use: the roll with more paper, or the roll with less paper?

Of course, if you're a selfish bastard then it doesn't matter as long as there's enough for you. But, is there any good reason that a decent person with concern for his fellow restroom user should choose one roll over the other? The answer is yes, and it's pretty obvious if you think about it. Unfortunately, it seems that very few people have thought about it.

You should choose the roll with less paper on it.

Why? Because, that way one of the rolls will empty faster and be available for replacement with a full roll when the maintenance person next checks. That will make it less likely that some unfortunate soul will be stranded with two empty rolls.

The world would be more pleasant if everyone followed this simple rule, but it's clear that they don't because I often see two rolls with roughly the same low amount of paper left. This is one of many cases where a misguided egalitarian tendency ("I think I'll use the roll with more paper because then they'll be more equal...") leads to unintended bad consequences.

UPDATE: An anonymous reader entered this comment:
A valid point, from an altruistic perspective. However, call me a "selfish bastard," but I always choose the roll with more paper. Why? More paper means fewer people have used it before, which in turn means that there is a lower probability that someone has contaminated the roll. So from a strictly personal standpoint, it may make more sense to use the full roll for hygienic reasons.
This is my response:
This is invalid. Only a brand new roll will be more hygienic (if the maintenance person who installed it is cleaner than the average user). But, after that they're equal. The inward-facing side of the paper is still as clean as the machine that rolled it. And only one circumference (plus a little) of a non-new roll may have been touched by others regardless of how much paper is left. I guess the edge may have been handled a bit more, but I suspect this difference is negligible. In fact, the smaller surface area of the roll with less paper probably more than compensates for any extra handling. So, be nice. OK? I don't think there's a real cost in this case.


UPDATE 2: Here is a nice design that implements my solution.