Complex Numbers

Sure Thing

It's hard to be certain of almost anything.

I say "almost" because there is one thing we can all be absolutely certain of: "I exist." Not me, I, but every one of us I, each to their own mind.

Now, you can play games with that, saying that "I" is an illusion, but it's difficult to argue with Descartes: I'm pink; therefore, I'm spam. Er, I mean, I think; therefore, I am. It doesn't matter if we're meat suits, actors on a stage, avatars in a simulation, or disembodied brains trying out this thing called material existence; we simply are. Well, I am. I'm not so sure about the rest of you lot.

In life, we all like to make statements with certainty, and find things we feel we can be absolutely sure of. Apart from my own existence, though, I'd put a degree of certainty on everything. Like, I'm sitting here looking at a kitten. Does the kitten exist, or is she a figment of my imagination? The scratches on my arm and the fact that I see her tell me she probably exists. Like, 10^-50 uncertainty, and I'd call that as certain as I can get about anything. I'll call this the kitten level of certainty - basically, indisputable proof.

Now, I understand that you've never seen this kitten (you should; she's incredibly cute), so your level of certainty that this kitten exists is - and should be - much lower. You only have my word on it, and I could be deluded or lyingcreating a fictional story to support a point. Her name is Katushka, and she actually belongs to my housemate, if it can be said that a cat belongs to anyone at all.

Does Afghanistan exist? I once met a person who said he was from Afghanistan. I've met a few people who claim to have been there and returned. I've seen it outlined on a map. I've heard reporters talking about it. It's usually first on the list of countries on dropdown menus on the internet. But I've never been there, myself, so I'd only give it a 10^-10 probability of nonexistence. After all, the only thing a map proves (to kitten levels of certainty) is that the map itself exists.

On the other end of the spectrum, if you were to ask me if my mother were alive, I'd have to give that a near-zero probability - the polar opposite of kitten level certainty. I mean, I watched her die, there's a death certificate, I saw her body in the coffin, and I was there when they lowered it into the ground. But memory could be playing tricks on me.

So if anyone were to ask me if I'm certain of - I don't know - the existence of the sun, the best I'll be able to do is kitten level certainty - and that's during the day if I'm outside. At night, it becomes slightly less certain.

I've been burned too many times by saying I'm certain about some fact or other, only to find out later that I misremembered or was misled. So I've learned - much to the annoyance of non-pedants everywhere - never to be 100% certain of anything.

This might become a problem if I'm ever in court. "Mr. Waltz, are you absolutely certain you saw someone drive off in your car?" "Well, I'm 99.999999999999% sure, but I suppose it could have driven off on its own, or maybe someone slipped me some acid." "So, you're not 100% certain."

So when I see something like "Only 66% of 18-24 year olds in the US are certain the Earth is round," it doesn't surprise me much (assuming that's even an actual statistic and not something made up out of thin air). But it worries me. Not because it implies that 34% of 18-24 year olds aren't completely certain the world is round (that statement says nothing about the level of certainty of the other 34%; it could range from "I believe the Earth is flat" to "I'm almost completely sure the Earth is round") - but because 66% of them are so absolutely sure of themselves that they don't stop to think that absolute certainty is (almost) absolutely impossible. I've never personally seen the curvature of the Earth, but I have seen ships disappear over the horizon, and I've looked at plenty of evidence, and heard statements from scientists and astronauts - so I'm going to give this one Afghanistan levels of certainty. In addition, "round" has a squishy definition when it comes to a planet. Obviously the Earth isn't perfectly round; it has ocean trenches and mountains, and an equatorial bulge - plus, if you consider the atmosphere to be part of Earth, its boundary isn't clearly defined.

Consequently, if you asked me "Are you certain the Earth is round?" well... I might answer "no" just to be pedantic about it.