IMHO, it's important to know the "rules" before you break them. Beyond just two-part counterpoint, I think it's important to know the Bach Chorale rules as have been alluded to here:
- No parallel or direct octaves or fifths (Google "direct fifths" if needed)
- Use contrary motion as much as possible
- With first inversions (3rd in the bass), no other thirds should be present in the upper voices (application: if the melody is singing the 3rd degree, don't play a first inversion in the bass line)
- Strong resolutions are stepwise or 5-1
- Second inversions are unstable; use them to build tension, e.g., a pedal point. They aren't inherently bad, you just have to know how to use them
- Leading tones (7ths) get resolved to the root (unless in the inner voices, you can cheat and resolve to the fifth if you need to--obviously, doesn't apply to bass!)
That's a fairly exhaustive list; I may have forgotten some stuff. But knowing these rules--and why they work--is VERY important for knowing how bass works with melody. Even people who haven't studied these rules yet who write great bass parts are using the rules many times just because they have good ears.
I think the no-3rds-in-the-upper-voices-of-a-first-inversion rule is a great sounding thing. I hardly ever break that one.
Yes, yes, I know this is all subjective. But the Bach rules are so persistent in music pedagogy because of their timeless beauty. Sure, break 'em (Jimi Hendrix + Jack Bruce = parallel octaves almost all the time), but know when to break 'em and why you are. I actually love the use of 2nd inversions; modern classical and film composers have used it to great effect to create instability. But you have to know that it's unstable. You have to know the tension you're creating and how to resolve it (or not) properly.
Being unable to "go meta" above the music you're playing can be limiting. Know as much as you can, learn as much as you can, listen as much as you can, then play what sounds good.
The stylistic considerations of common practice counterpoint are rules specifically designed to construct a particular aesthetic, and are not some how overarching rules designed to cover all styles of music. They simply don't apply in any meaningful way to the majority of contemporary music. More important are the overarching principles of counterpoint regardless of style which include...
*melodic contour
*control of intervallic dissonance
*independence of the voices
*registration
Etc.
The specifics change from style to style, but the underlying principles remain the same. Strict rules from the Baroque aesthetic are merely "considerations" in the big picture of counterpoint.
Jimi Hendrix was NOT breaking any rules of music when he was playing in octaves - he simply wasn't using counterpoint. Not using counterpoint isn't tantamount to heresy, it's just not using counterpoint. Parallel fifths aren't bad, so long as it fits within the aesthetic that has been chosen. To think that they were somehow "rebels," bucking the conventional thinking is rather ludicrous, they simply were using different musical techniques besides counterpoint that had been used for hundreds of years.
To ChrisK...
Parallel 5ths already appear in the late 18th century (the famous 'Mozart's 5th') and were used more and more widely ever since. But those composers knew what they did. They wrote their 5ths on purpose. They paved the road for composers and arrangers who obviously didn't know their stuff that well, or believed that forbidden parallels did not matter anymore.
Interestingly, there are a good number examples of Bach using parallel fifths and octaves (Fugue in E minor from WTC Book 1, for example), but there are always extremely good reasons for doing so. The reason why parallel perfect consonance is bad is because it can work to destroy the independence of the voices (one of the core principles of counterpoint). Sometimes, however, independence of the voices isn't desired, or if harmonic/melodic circumstances (Mozart 5ths) force their use in an otherwise polyphonic texture.
I disagree. The collective musical memory of people who grew up with western music still 'notices' violations of those ancient rules, in such a way that ordinary people who know nothing about music will like arragements better if they have been written by an arranger who generally applies those ancient rules. I noticed this on many occasions where I rewrote the work of others.
I both agree and disagree. I've worked with enough students new to part writing to know that it takes a little bit of training to really hear "incorrect" parallelisms, and at first they generally have to be told "this is the way it is, do it." To think that the untrained public will be especially adverse to the occasional parallel fifth in multiphonic texture where it isn't supposed might be putting too much faith in a public which hasn't grown up in the Baroque aesthetic. However, harmonization in imperfect consonance - which is more or less a Baroque ideal - can only be called a universal truth. It works well for practically any kind of music. This idea could hardly be called an "ancient rule," but rather, it relates to the control of dissonance, one of the primary concepts of counterpoint.