Roy G. B’v visits Narnia

I know, things have been quiet around here lately. Nowadays, I mostly post at The Confessional Outhouse, but this little tidbit I thought was cool enough to share, and not really aligned with the mission of the ‘house:

Young kids are often taught about Roy G. Biv, a hypothetical gentleman who helps them remember the seven colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet. Even kindergartners tend to rebel at the mysterious ‘I’ in Mr. Biv’s name, however. What the hell is indigo? It has to be explained to them that indigo, halfway between blue and purple, is actually a very different, super-important color, trust us.

In fact, indigo is a bit of a fraud. The other six “colors of the rainbow” are the long-enshrined primary and secondary colors of art theory. Indigo only got shoehorned into the rainbow because Isaac Newton, who originally saw five colors in the spectrum, decided decades later when he wrote his landmark treatise Opticks that seven would be a more elegant number. He believed the seven colors should harmonize somehow with the seven classical “planets” in the night sky and the seven notes on the diatonic scale. So he added orange, along with indigo, an important dark blue dye since ancient times. In reality, most observers have a hard time seeing indigo as a separate band of the spectrum, and it’s not usually included in modern color theory.

If indigo is iffy, how many colors are there really? Well, the human eye can distinguish between about a million different hues, but a real rainbow displays its shades in one continuous spectrum, not the neat stripes of a Care Bears cartoon. In the Iliad, Homer refers to a one-tone purple rainbow, because the ancient Greeks didn’t have words for the full spectrum of color. Later classical and medieval thinkers agreed with Aristotle that the rainbow had three shades; in Islamic thought, there are four, corresponding to the four elements. So it’s largely a cultural call. Many Asian languages, even today, use the same word for “blue” or “green” — someone in China might describe the rainbow very differently from someone in Finland, or Papua New Guinea. Let’s just say there’s a wide spectrum of possibilities.

Although this is cool and neat by itself, what really caught my eye was that we owe our 7-color rainbow to Newton’s dependence on the medieval seven-planets as an organizing principle for other (all?) areas of life.

Have you ever asked yourself why there are seven Narnia books, and what holds them together, though they all seem so very different? It turns out that C.S. Lewis scholars have been trying to answer that question for over 50 years, and after many unconvincing attempts to systematize Narnia (plays of Shakespeare, days of the week, …), Anglican priest and Lewis specialist Michael Ward had an epiphany that Lewis was (just like Newton) using the seven medieval “planets” (Mercury, Venus, Mars, Jupiter, Saturn, Sun, Moon) to organize his creative vision — and even subversively using the Narnia series to attempt to re-interject awareness of the seven medieval planetary ideals into the modern consciousness.

For more information, you could go read Ward’s book for lay readers, The Narnia Code, or his academic book (Warning! English professors only beyond this point!) Planet Narnia, or listen to him talk about it on Mars Hill Audio Journal #90, or hear the extended discussion from Mars Hill Audio: Conversations. Or you could just go poke around the man’s website.

And while you’re doing so, you can be listening to this cute song from my favorite band, even though it is now obsolete (maybe they’ll write a new song, like they did when this song had to be corrected).

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Today’s Lesson in Logic

From Boing-Boing, some guy named Mark Frauenfelder brings us a brilliant example of the logical fallacy known as Post hoc, ergo propter hoc:

Fraunfelder jokes, based on the pictures, “It’s conclusive: owning a passport will prevent you from becoming diabetic.” 

More exactly, this is the related fallacy with the latin name Cum hoc, ergo propter hoc. Those latin phrases mean “After/with this, therefore because of this.” Both of those fallacies fall in the category of Non causa, pro causa (“Non-cause for cause”). When two effects are seen, one fallaciously assumes that one effect caused the other. In reality, logic allows that the two effects are both caused by other, common causes — in this case, probably things like poverty, education, ethnic diversity, etc.

Another correct way to approach this kind of data, is to remember the statistical truth, “correlation does not imply causation.” In this case, populations that are more likely to have passports, are also more likely to have diabetes — so passport-ownership and diabetes are correlated. But that doesn’t mean that passports cause diabetes (any more than getting diabetes will get you a passport)!