Four Part Writing - Root Position Triads

Hi,

I have a few questions regarding four part writing. Walter Piston presents two "rules of Thumbs" in the first chapter of voice leading in the major mode. Then he proceeds to teach the various means of voice leading such as crossed voices, direct 5th/8vs and bad parallels. What confuses me is this, are these rules of thumb actual laws? I've never heard of them, nor have I witnessed an equivalent of them in any text regarding this subject. He moves on to the aformentioned rules of four part writing after talking about ways of departing from the rules of thumb. Can anybody shed some light on this for me? Those rules of thumbs are:

1.If two triads have one or more tones in common, these common tones are usually repeated in the same voice, the remaining voice or voices moving to the nearest tones of the second chord.

Exception: In the progression II-V, when the fourth degree is in the soprano of II, it is customary not to repeat the common tone, but to move the upper three voices down to the next available position. (This motion may, but need not, be used when the fourth degree is in the alto or tenor.

2.If the two triads have no tones in common, the upper three voices move in opposite direction to the motion of the bass, but always to the nearest available position.

Exception: In the progression V-VI, the leading tone moves up to the tonic, while the other two voices descend to the nearest position in the chord. The third, rather than the root, is doubled in the triad on VI. This exception always holds true when the leading tone is in the soprano of V; when it is in an inner voice, either the rule or the exception may apply.

Edit: I would just like to add, on the subject of doubling? I read that the rule is to double the root. In the vast majority of instances, I find that this creates no problems. But in the event that it does, is it customary to double something else? Preferably the third? And what constitutes a better move from another in the same progression, as Walter Piston's text shows several examples of the same progression in different positions and makes it know that x is more satisfactory than y, without stating why.

My appologies in advance for my ignorance on the subject. Any help will be gratefully received.

Many of things you mention are indeed absolute rules in common-practice harmony. Thus, two voices may not move in parallel fifths or octaves, parts should not cross, suspensions must be prepared and resolved, etc.

To address your specific questions:

#1. This rather depends on what one is harmonising. In a chorale the soprano melody is fixed so you would have no choice about whether a common tone was to be repeated or not. If it is original work, then the rule you cite probably came about to avoid having a static soprano line. The sopranos can descend a third in this progression without any risk of there being parallel intervals as all the other voices are moving upwards. However, if the progression was IIb - V - I then writing this fall from the common tone is less advisable, as it is then very difficult to avoid both parallel octaves and doubling of the third in the V chord.

#2. The exception you describe is indeed the best way of writing this progression, and voices should always move the shortest distance if there are no common tones. However, this situation occurs because one is moving to a consecutive chord, which whilst not against the rules is less encouraged than moving to a more closely related harmony.

#3. Doubling the root or the fifth is the most common. Doubling the third is not encouraged, and never if the chord is in first inversion. The only exception is if it is problematic to write a chord containing the fifth degree (perhaps because of range or voice-leading) in which case one may write the root and the third only in the four voices.

I teach chorale harmony (amongst other things) in the Lessons section here, so PM me if you want lessons.

Well, the short answer is that these rules of thumb are also described in other textbooks. But (if I remember correctly) these rules are just made up by induction of the principles used by old composers who did use rules but these were the rules of counterpoint and not of voiceleading. Voiceleading is in principle not much easier than counterpoint, but in practice I'd say it is.

These rules of thumbs are, of course, no actual laws. You are free to stretch their boundaries, or leave them altogether. Modern composers don't use these principles of voiceleading too often, but even composers like beethoven and mozart and bach etc did not always totally adhere to them - especially in instrumental (keyboard)music. Basically, these rules are a way of making sure that (in classical composing) the voices and harmonies shift as smoothly and as pleasant as possible, and making sure that every voice is very much independent and moves stepwise and logic (that is the why for those rules regarding crossing of voices, paralles etc). The rules are based on vocal music, and because vocal music has it's limitations (the pitches have to be created by the voice, not just by putting a finger down on a piano or violin) people wanted to write for it in such a way that it would not give any trouble when singing.

Those 2 rules you stated are ways of making sure that all the voices move as little as possible between chords, because large leaps are harder to sing than small leaps. And they also make sure that no voice is deprived of its 'independence' to the others: if two voices move in unison or octave, they are practically doing the same, therefore making the distinction between the two hard/impossible. I think this fascination for independence came with the polyphonic practices and stayed even when composers were beginning to write more monophonic.

The 5th is doubled if the root cannot or isnot to be doubled. Just make sure that the leading tone (7th tone in a scale) is never doubled: it is too dissonant for that (according to the rules ofcourse).

'More satisfying' would mean that the total amount of stepsize is smaller, that some form (like a cadence) is used, or that they just voted before sending the book into print on what voiceleading between chords would be most agreeable - and that one won.

EDIT: Ah yes, to the how and why for specific exceptions you should listen to someone like siwi

In traditional western harmony, they are laws. You'll hardly ever see them broken.

You have to keep in mind that theory FOLLOWS practice, and the practice is that composers of old innately followed the rules not because they "had" to but just because that was the aesthetic.

Some of them still tend to hold true (parallel fifths, direct octaves, jumping around voicings still have the "archaic" connonation that it had back then), but most of them don't matter for modern compositions (parallel fifths on electric guitar are flippin' sick). Unless you're trying to emulate the old style, of course.

Oh, btw, welcome to YC! ;D Nice FFVII allusion.