Next time you decided to sit down and read Major Barbara, Man and Superman, Pygmalion, or any play by George Bernard Shaw, take the extra time to sit down and read the prologues. While not theatrical in nature and usually a little more than politically minded, you will find no better written example of how to pose an argument. Written to appeal to the intellect, the pieces are declarative and persuasive.
But if you sit down and not only read the prologues, but read them out loud as a sort of debate or oratory and really put in the effort to make the text work, you start to find something extraordinary. Nor only are they exceptionally wells suited to be read aloud, but they sound very similar to the dialogue of his plays.
For his plays themselves are arguments. He is calling for changes to everyday life or at the very lest, for people to think about what is going on around them. Shaw chooses to write in comedy because the laughter at the end of the line is the audience "getting" the idea that the play is trying to convey, recognizing the inherent silliness expressed, and identifying with the humor. There is no better way to know for sure if you audience is following your work than listening to whether they are laughing or not.
So take some time to actually do this; especially you actors out there. It is an excellent exercises that will improve your performance in not only the language based playwrights like Shakespeare, Coward, and Stoppard but any other playwright you come across. Shaw makes you think about what you are saying and work very hard to make sure that your partner and audience understand it too. And that is what line delivery is all about, isn't it?