The bit about the mirrors is actually quite stupid: they don't reverse anything, but we expect them to selectively reverse left and right, because that's how we see it.

It's a stupid joke in one sense, but the phenomenon is arguably caused in the same way that humans tend to mistake cause for effect (or even just plain bad correlation/causation claims.) And that is more the point of this wordy treatment than the etymological trivia that I'm about to dive into. I will get to the point.

Arguably, humans think in analogies. Our language about logic and reasoning is peppered with it. When things have the same effect to all relevant respects, logic calls them "equivalent" (they have equal valency), which doesn't mean they're the self-same thing (identity) or even that they're the same in all respects, but that they behave exactly the same for all purposes. Those purposes are generally supplied by context, and they define the relevant properties that we will count as our valencies.

Rectitude, on the other hand is, in my mind, a kind of macro-equivalence. Regardless of how you think about it however, a thing that is correct in math and logic is accounted for by checking equivalences the whole way through the proof. To say something is correct not just to say that it is right, but that it is right with itself, or with respect to its basis for comparison (generally, the problem to be solved.)

The point of all this is that correctness more easily applied to the world around us than equivalence is, but I want to show the relationship between correctness and equivalence.

Now for something a little different, without too much talk of words. I was tempted to use text to demonstrate this, but I feel like breaking from tradition and also I promised not to go on about words anymore. So, here we go:

So it's a bird. A bluebird in fact. You might not have known it was a bluebird, but if you've read this far we can safely assume you've recognized it as a bird at least. I'm pointing this out not to be condescending, but to bring it to your attention that you've recognized it. Probably fairly quickly despite the small size of the image. Now try again:

You've certainly recognized this as a bird, and almost as certainly, you've recognized it as not only a bluebird, but the same bluebird, in fact the same picture. However, it's been rotated 180 degrees.

It didn't take you long to do so, and that is the point. It's very different from an absolute point of view, but the context allowed you to redefine 'up' for the image, with respect to itself. You could do it with reflection as well. Others have gone on about this very phenomenon, and they like to use letters and symbols to show that people measure these things topologically. This instance is a bit more robust, but I'm sure you've done just as well. Congratualtions, you're a human. Okay, you're an animal. All animals equipped with robust vision can pull off this feat because they must. Things are rarely on the level in nature.

The truth about the mirror is that while we're familiar with reflection, it is not so common as rotation. Visually speaking, we screw it up because when you see someone in front of you, facing you, you expect them to be rotated. The only thing mirrors invert is the depth, front to back, and this is why you find it counterintuitive to brush your hair or shave in a mirror.

This kind of mistake is made in logic as well. Under some circumstances it's easier to mistakenly reverse a whole thing than it is to fail to carry a one. If you get the whole thing flipped around or even reflected, it's still an internally stable construct. And it's still correct with respect to itself. The modular way in which we like to handle things means that it's easy to leave out the relationship of the part to the whole while considering the part for internal consistency.

Think about it: it's got all the same slots and tabs and dimples and bumps as it would otherwise have, and they're all placed properly with respect to each other. So the inverted part is self equivalent in the exact same way that the non-inverted part is. If you leave orientation out of your considerations, the two are equivalent.

But sometimes they're not correct. Sometimes you have a stereo image. Sometimes you have a study that shows only a correlation used in an argument that x causes y, when it's really up for debate, or possibly the reverse, or possibly they're common effects of a cause z.

Unfortunately this stuff isn't always intuitive. If you don't pay attention (or simply don't think analytically) you can make some fairly serious mistakes, sometimes even concluding the opposite of what is true.

Honestly this stuff should be taught in schools. Ignorance of it causes a lot of problems (or rather, a lot of problems could be avoided by understanding of the phenomenon.) I'm not just talking about scientists, but teachers and politicians make this kind of mistake all the time, as do interest groups. These people make changes to the way people think, the way policies are made and sometimes even make law. Sometimes it ends up poorly flawed and no good comes of it. As the human experience gets more complex, more opportunities for inversion arise and more people are around to suffer the consequences.

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Aside:
I was born in the late '70s and so learned most things about the world on a global scale during the '80s. There was such a sense of optimism and more importantly common progress that permeated the era that it left a mark on me. Nowadays everything is the complicated by a kind of unproductive competition. If I were to say that today's enterprise does not employ bloody war as a business practice, how many of you would wholeheartedly agree?

When I read about the Norwegian Seed Bank, I could hardly believe it. This isn't exactly the kind of thing that builds a better tomorrow, but it does help reduce the magnitude of the worst case scenario. Unfortunately it is also an example of the necessary pessimism that go with these times.