After I wrote my thumbnail sketch of positive discipline (which I'm going to abbreviate to PD, for ease - that's how it's generally referred to on the list I'm on), my sister followed up with a comment on the next post that raised a couple of excellent points - namely, that there is a place in discipline both for teaching specific behaviours (such as saying please and thank you) and for setting firm limits. I completely agree with both of those, so I'm glad she raised the points. (Do please keep any other queries coming, folks - I was trying to write a summary of how the PD approach differs from other approaches, not a complete explanation of everything in the theory, so there are inevitably some big gaps and some yes-but-what-abouts.)
PD is often mistaken for a philosophy of letting kids do just what they want, but, in fact, normally PD advocates absolutely do agree with setting firm limits where appropriate. (They may well set fewer limits simply because of a don't-sweat-the-small-stuff approach - sometimes we get worked up about a particular behaviour because society expects us to/we feel we should rather than because it's actually causing any harm, and PD encourages parents to think more flexibly about these sorts of issues - but the basic principle of settling limits where it is appropriate remains the same.) There's even a name for this - GOYB parenting, which stands for 'Get Off Your Butt' (and go and actually move the child away from whatever they're not supposed to be doing). The difference between PD and other forms of parenting lies in how you approach the situation after that.
So, for example, let's say one of your children launches into a fists-flying attack on another. I think everyone other than utterly neglectful or ineffectual parents can agree on what the immediate response needs to be to that: grab that child, pull him or her off the other one, and physically restrain him/her if necessary to stop the hitting. The question is - what do you do after that? (If you're the kind of exhausted drained wiped-out just-getting-through-the-day-please-god parent I was in my children's early years, the answer is admittedly "Tell them to stop doing that and then let it drop", but I'm talking parenting philosophies here.)
Traditional advice would be to smack the offender, to give them the message that they need to avoid that behaviour in future. More modern parenting experts point out the illogicality of hitting a child to teach them not to hit, and advise time-out instead - if this is a recurring problem, one of today's experts might also advise a reward scheme with some sort of goody given out for periods of time spent 'playing nicely' together (this is, indeed, the first example given in the chapter on rewards in the Webster-Stratton book.) But the PD approach would be to take this as an opportunity to guide the child through developing the skills needed to handle this situation better.
For example, you could start by acknowledging the child's feelings at the same time as clarifying the limit - "Oh, my goodness, you're so angry with Jimmy, aren't you? We don't hit people, even when we're angry - we need to find another way to sort this out." You could help the child to calm down, if needed. And then you could find out what set this off, and talk through better ways of handling the situation when it next comes up.
(Another prominent feature of PD, though not unique to it, is to look at what else may have been going on to predispose to that particular behaviour. Is the real underlying problem here that your child is hungry/tired/bored/stressed out over life changes? If so, that gives you things to work on to either improve the situation now or reduce the chances of the same thing happening in the future.)
You may well be wondering whether PD-practicing parents have to do this every single time we run into a discipline problem with our children, and of course we don't - life's too short, and you don't always have time to sit down and have this sort of conversation. That's OK. If the problem comes up again you can deal with it then, and if it doesn't then you don't have a problem anyway. But, in general, you look to use these times as a chance to teach your child something about how to handle life, rather than as a challenge to your authority or as a surface behaviour to be squelched.
And, yes, I also agree that sometimes the skill you need to teach the child in a particular situation is a simple behaviour ("Say please") rather than a detailed consideration of complex moral issues/social mores.