(I started to cover the Barber paradox, but then I realized that it has been presented in just about the exact same form all over the internet, and people often get hung up on the gender of the barber, which really isn’t the point. So, here’s a gender-neutral version. Enjoy.)
Here’s a rule that we’re going to try and follow:
“In a certain town, a tailor mends the clothes of all those, and only those, that don’t mend their own.”
At first glance, this seems completely logical. If a person can mend their own clothes, then they will, but if they can’t, they’ll go to the tailor. This situation breaks down into a paradox, however, when you ask the seemingly innocent question,
“Does the tailor mend their own clothes?”
Now, in reality, of course a tailor would mend their own clothes. Why would they have someone else do it? But remember, this isn’t reality, and we set some logical rules at the beginning that we must follow. See, if the tailor were to mend their own clothes, then they would fall into the category of “those who mend their own,” which is precisely the category that the tailor does not mend clothes for. The tailor can only fix the clothes of people who can’t do it themselves- and since the tailor can do it themself, they cannot do it themself.
I don’t know of any applications of this paradox, and I can’t think of any real-world examples. I do think it is interesting, though, how this paradox demonstrates the important difference between our world, and the world of logic. In our world, human behaviors never stick to one-sentence, simple rules. There are exceptions, loopholes, and people who don’t follow the rule just because they know it exists. If you tried to write the actual rule that real-life tailors use, it might start something like this:
“The tailor will mend the clothes of all those who don’t mend their own (with the exception of the tailor,) have the money to pay the tailor, have knowledge of where a tailor is located in their community, is willing to pay for a fix rather than throw their clothing away, and can find time in their schedule to drive to the tailor.”
That rule is several times longer than the one our fictional tailor used, and yet still, it has exceptions. There are people who fit every single one of those requirements, but continue to wear ripped clothing because it looks cool. There are also people who meet none of the requirements, yet still go to the tailor. Perhaps someone who has mended their own clothes before, but is in such a time crunch that when they find a tailor by driving around downtown after another errand, they reluctantly use their credit card to pay for the mending with money they don’t have.
All we’re trying to do is explain one simple, binary human behavior, but already we’ve
had to consider fashion trends, including what is ‘cool’, scheduling, the complex worldwide credit card system, and the psychology of stress. Just to determine who will go to the tailor!
The world is absurdly complex, but sometimes we let ourselves use simple rules anyway, and we pretend they always apply. We tell ourselves that all people of a particular religion are good, or that killing is always bad, or that smart kids always do well in school. And sometimes we do need to simplify, but other times it’s worth it to sit back and remind yourself that the world you move through is incredibly complicated, and we’re all just trying to make sense of it together.