Why is the alphabet in alphabetical order?
I saw this as a joke somewhere, but it got me wondering what the answer was. Why is the alphabet in that order? Who decided A was the first letter, B was the second, and so on?
You missed the point of the joke, sport. Let's take it from the top: Why is the alphabet in alphabetical order? Ignoring the smart-ass element, we may restate this as: Why is the alphabet in any (never mind some particular) prescribed order? Obvious (to me) answer: to make it easier for kids to memorize. It's working, too. Notwithstanding its inscrutable origins, ABC order as we know it now has survived more or less intact for upwards of 3,000 years.
The alphabet used in English, and with some variations in most other European languages, comes from Semitic speakers who adapted it from Egyptian hieroglyphics about 4,000 years ago. The rudiments of modern alphabetic order first appeared about 600 years later in Syria. With minor changes in letter order at each step, the alphabet passed from the Semites (including the Canaanites, Hebrews, and Phoenicians) to the Greeks to the Etruscans to the forebears of the Romans to us. As for the identity of the sage who first ordered it, and why that order, your guess is as good as mine.
There's no obvious reason ABC is better than any other order. The dominant script of Ethiopia is related to our alphabet but uses a different order, likewise rooted in antiquity, based partly on letter shape. The more closely related Arabic script descends from an early alphabet having the same basic order as ours, but the letters have been partially rearranged according to shape and sound. The letters in the Irish writing system ogham, some of which were named after trees, began B, L, F. The Germanic runic script known as futhark is named after its first six letters ("th" represents one of them).
The roots of ABC order are found in the cuneiform script of Ugaritic, the Semitic language of an ancient city in Syria. The letter shapes of this script aren't obviously related to our alphabet's direct ancestors, but the alphabetic order from a 14th-century BC inscription is virtually identical to later Hebrew and Phoenician letter lists, and the letter names are related.
A Greek borrowed the 22 Phoenician letters around 800 BC - I say "a Greek" because idiosyncratic errors suggest one absentminded genius botched the job. Among other mistakes, he got several sibilant letters mixed up, and by the time things calmed down S and Z were the wrong shape and S was out of order. The same joker, or one who followed closely, gave exclusively vowel sounds to four letters theretofore primarily consonantal: ancestors of A, E, I, and O. Later Greeks added letters to the end, two of which interest us: chi, ancestral X, which over time acquired our modern "ks" sound; and upsilon, ancestral U, which was probably a vowel variant of the semivowel wau, since dropped from the Greek alphabet but ancestral to F.
The Etruscans borrowed the Greek alphabet about 700 BC. They retained the letter order but dispensed with the Semitic-derived letter names, which is why we say "ay, bee," not "alpha, beta." (British zed, from zeta, is a holdout.)
Latin borrowed the Etruscan alphabet about 600 BC. The Etruscans had no G sound and thus no corresponding letter, so eventually Latin G evolved from C - fittingly, because Etruscan C (pronounced "k") had come from the Greek gamma (pronounced "g" as in, well, gamma). Rather than sitting next to its sib, G took slot seven, replacing underutilized Z. Centuries later Z came back to transliterate Greek zeta and Y was introduced to represent upsilon. As newbies, Y and Z had to sit in the back.
The modern English alphabet is the 23-letter Latin assortment with three additions hastened by the invention of movable type. W starts showing up in English letter lists in the 16th century, replacing the previous literal double U (or V) that denoted our current W sound. Naturally it was placed next to the then-undifferentiated U/V. The I/J and U/V cleavages came later - though the different shapes had existed for centuries, they weren't considered distinct letters in English until around 1700.
So the roots of ABC order trace back to 14th-century BC Ugaritic. But why that order? Scholars don't know, but that hasn't stopped them from pulling wild guesses out of their urtexts. There's some slight, possibly coincidental correspondence between the meanings of the Semitic names of adjacent letters - for example, the yod-kaph-lamed sequence, meaning "hand, palm, cattle prod." Other explanations involve astrology, Sumerian musical scales, and divine intervention; one knucklehead even proposed that the Phoenicians named and ordered their letters after the days of the month in the Mayan calendar. Damn foolishness, all of it. The point isn't what order the alphabet is in, but that it's in order at all.