Being "in a key"
Kevin Drum offers appreciation for anyone who can explain the musical concept of the "key of F Minor" or the "key of G Major" in a way that makes sense. I offer this explanation (instead).

First things first, there are 2 separate ideas at work in the phrase in question, that are basically unrelated and we should keep distinct. "F Minor", "G Major", etc... have, first, the name of a pitch (F, G, Eb, whatever) and, second, the name of what we call in the bidness a "mode" (minor, major are the 2 most common and there are others you don't much hear about..). The pitch and the mode convey 2 completely different phenomena, both at work. So being in G Major tells of a central pitch (G) and provides a map to the other pitches above and below it (in this case, the pattern we call "major") that are in play.

So let's take the pitch first, that the key is named for. Being in the "key of F..." or the key of G..." refers to the pitch that is experienced as the musical center of a piece/song/whatever. All "tonal" music, by definition, has such a pitch center.

What does it mean to be the tonal "center"? For starters, put music in the same category as literature and film in this sense: it is a narrative art that unfolds over time. And like other Western narrative art forms, the controlling metaphor is that of a journey. The tonal center, which we teach students to think of in terms of a "home" or base of departure and arrival, is experienced most recongizably as beginning and ending points in that journey.

Of course, a musical narrative is not a journey with only one direction like most stories we know, with one scene following another. Music is typically full of repeats, refrains, and reminders. And while those surface elements (like melodies that keep coming back, or a repeating chorus for example) are the most recognizable and memorable, and are the things that distinguish one piece in F from another, the tonal center - the key - functions as a more fundamental, deeply buried element of musical narrative. It is the thing that gives each departure and return a sense of arrival with each return of the tonal center, and a powerful sense of closure when it sounds an ending.

But key is a concept that's easier to grasp as experience than explanation. Try this experiment: sing Happy Birthday all the way through for yourself. Or our National Anthem is another good example. And when you get to the very last note, the very last word ("you" or "brave"), instead of singing the note you know is correct for the tune, make the last note a repeat of the previous one ("to you" or "the brave" on the same pitch, rather than falling down to the proper note at the end). The last note will sound incorrect. But it doesn't sound incorrect to you just because you know how the song really goes. It also sounds incomplete, as though the song isn't quite finished. That's because the tonal center (the last note in both of these cases) is avoided.

If you sing them as I suggested, the words come to an end, the meter/rhythm comes to closure, but the tonal center of the piece is thwarted. (Melodies don't always end on the tonal center; in fact, the chord structures--especially the bass--establish the "home key" most strongly. But melodies often reinforce it.)

So, being in F, or in G, means that the pitch F or G is functioning as the tonal center that establishes closure in a musical narrative.

As for the second element--"major" or "minor"--that refers to the other notes: the pattern of steps above and below the tonal center that identifies the other pitches in the color palette being used in a given piece. This is the "mode" or "scale" of 7 different pitches (7 in Western tonal music, anyway) including the tonal center, that make up the primary cast of characters in a musical narrative. Start with "C" on your piano and play up or down on the white keys only and you will have the pitches of "C Major." It is a pattern of steps/distances/intervals away from the center. Using the same pattern from a different pitch as the center, you will still have "major" as the "mode," but a different pitch will be functioning as the tonal center. That is why you can sing happy birthday recognizably starting on any pitch, because tonal music is not made up of notes; it's made up of interval-patterns.

As you may have guessed, "Minor" is a different pattern of steps from the center than major, and one that offers a different harmonic effect. Between the 2 primary modes, major and minor, we manage to convey a variety of conflicting emotions, including both happy and sad (I won't bore you with the reasons for that) and so the development of other modes as musical standards has never really happened. That's why people like me get excited when someone like Sting writes a tune in a mode other than major or minor. He does it occasionally. Early Pearl Jam was a mode festival as well. Bartok and Debussy experimented with modes extensively.

So am I saying Western music only ever has 7 notes? No, of course not. But, let's face it our tuning system only has 12 different pitch-classes (A through G plus the black keys). More music than you might think does in fact use only 7 different pitch-classes from beginning to end. Occasionally even fewer than that get used. But being "in F Major" doesn't limit you from ever stepping outside the parameters of those pitches.

Shifts and slight alterations in mode are common (chromaticisms, they're called). If you want a good example that's pretty easy to hear, brush off your copy of Magical Mystery Tour and play track number 2, "Fool on the Hill." They shift the mode early on, when they get to the line "But the fool on the hill sees the sun going down and the eyes in his head see the world spinning round." That phrase is in "minor" even though the rest of the tune is in major. So, the mode shifts, abruptly in this case, and then abruptly back after that phrase. But, the tonal center doesn't change (they sing the "home pitch" at the end of the phrase, on "round"--it helps make the shift from minor back to major a smooth one).

If you read this far, you know now a couple of things--hopefully what "the key of F Major" means on some level, but for sure you also have a glimpse into why I don't get dates...

Maybe next week -- if there's a public outcry -- I'll explain how, in an invention of convenience that allows us to play with any of the 12 pitch-classes as a tonal center with one instrument, we fudge and approximate all the tuning. That's right, tuning is a natural phenomenon, but our pianos are not in tune with themselves.

{edited somewhat...believe it or not this was even less readable before...thanks for help from a reader.}