Unexpected Nonexistence

René Descartes walks into a bar. He asks for a beer, but the bartender says, "Wouldn't you rather have an appletini?" To this, Descartes replies, "I think not." And he disappears.

This joke kills at philosophy conferences. René Descartes is a famous mathematician who gave us the Cartesian coordinate system, most of the notation we use today, and a variety of other mathematical ideas. He is also the reason we call the imaginary numbers imaginary. He thought the idea of square roots of negative numbers was stupid. So he called them imaginary as opposed to the numbers he liked which he called real. This is unfortunate because many people then think that imaginary numbers don't exist while real numbers do. But that's not the case. Imaginary numbers are no less real than real numbers and real number are no less imaginary than imaginary numbers.

Setting all of that aside, Descartes is also famous as a philosopher. His best known quote is "Cogito ergo sum" or, in English, "I think, therefore I am." This was a thought experiment in which Descartes wanted to ask what does he really know to be true. Imagine that you can't trust your senses, what you see may be false, what you touch may be false. Can you make any conclusions? Descartes did, he concluded that the very fact that he could ask this question, that he could doubt his own existence meant that he must exist in some form. Maybe his body was fake, but there had to be some mind, something capable of thinking. So he did exist.

The joke plays on "I think, therefore I am." Though, it is logically flawed because it is then accepting "I think not, therefore I am not." That's the inverse of Descartes's original statement and the inverse of a proposition may not have the same truth value as the statement. The philosophers know this, but somehow they still find it funny.

Alrica and I ran into our own question of existence, though not our personal existence. We arrived in Tirana, Albania on Tuesday night. It was a slow bus trip from the airport to the city because of an accident on the highway. But eventually we made it. And we got to the place we are staying.

On the way to our place, we walked down the Rruga Him Kolli. (Rruga is the Albanian word for street or road. Him Kolli is the name of the street.) Much of it was deserted and dim, though there is a Spar grocery store and a pizza place. But the next day we went out while the sun was shining. And this nocturnally dim, empty street is super non-empty in the day. There are fruit and vegetable stands lining both sides of the road. We are living right off of fruit street! One thing I love about many other places is the availability of low-cost, high-quality produce. You can't get everything at every time of year, only what's ripe now. But it is so fresh and delicious and good for you.

We also bought a fruit with which we are not very familiar. It looks like a big pear but with bulges in the pear shape. We asked the woman at the produce market what it was called, though she didn't understand us. So I pointed to bananas and said "banane" and then to tomatoes and said "domate" and then to this fruit. She understood and told us it is called "ftui". I don't know the first thing about eating ftui, so I looked it up. This is a quince, in English, rhymes with wince. In Spanish, the word quince means fifteen, it isn't a fruit, and it rhymes with mean say. But we are taking about the fruit here, not the number. Turns out, you have to cook a quince before you eat it or it is so astringent you won't enjoy it. (Sadly, the cook time is NOT fifteen minutes, which would be such a beautiful convergence of coincidences, I might have to doubt my existence.) I might cook a quince today!

Look, a fifteen! No, no, that's the fruit version of quince.

But the quince being a fruit and not a number (neither real or imaginary) is not the existence problem. We continued our shopping for essentials. We stopped at more than just fruit and vegetable markets. We bought bread at a local bakery. We bought cheese and butter at a dairy store. And we bought some regular groceries (and things like toothpaste) at the Spar, which as I mentioned, is a grocery store. One of the things we picked up off the shelf was a vinaigrette dressing. We had purchased tomatoes at the produce market, purchased feta cheese at the dairy market, and Alrica makes a fantastic tomato and feta salad that uses, (I bet you can guess,) vinaigrette. But when we got to the checkout counter, our cashier had a problem. She scanned the vinaigrette and it didn't scan. She tried again and again. She typed in the barcode number. But it wouldn't go through.

Our cashier did know some English and she told us, while holding up the bottle, "This does not exist." Obviously, she is of the Descartes school of though. Even though she can feel it in her hand, and she can see it in front of her, that doesn't prove its existence. It is kind of a modern day "I think, therefore I am." But this one is "The computer doesn't know this product, therefore it isn't."

Alrica solved this by darting back to the shelves and buying a different brand of vinaigrette that happily does exist. (We ate the salad last night, and so I also have my sense of taste to back up my senses of sight and touch.) But I wonder this: Couldn't I have just taken the non-existent vinaigrette without paying for it? It's not theft if the item doesn't exist, right?

Don't worry, I didn't test my hypothesis. Because if I were wrong my ultimate conclusion would be "I am imprisoned, therefore the vinaigrette exists." And even Descartes would agree that's not worth it. Assuming he existed.