Dramaturgy is one of the best-kept secrets in professional theatre. The secrecy is unintentional, of course. Like all well-kept secrets, the reason no one talks about it is because they think that it is boring, redundant, or otherwise unnecessary -- until they need it, that is.
"Dramaturgy" means "research and/or theory for and about theatrical plays in performance." Dramaturgs (or "dramaturges," if you're a Brit), do all kinds of odd jobs such as looking up difficult words or obscure references in the play's text, answering questions for the director, designers, and actors about the meaning or context of elements found in the play, and often, if the play is being devised or is not under copyright, we're the ones who make alterations to the script itself. We cut, add, copy and paste, substitute, re-gender, or make whatever modifications are necessary if the director wants to set the play in a different place or time.
Sacrilege? Meh. If you say so. But please keep in mind that there was never just one version of any Shakespeare play, and that the original typesetters, as well as Shakespeare himself, made alterations all the time out of fancy, error, or convenience, and modern editors of those precious "full texts" are no different. If you compare a facsimile of the 1623 First Folio with that "Complete Works of William Shakespeare" sitting on your shelf, you will discover that we have to interpret and intervene all the time in order to take the spellings that we find in the 400-year-old print editions and transliterate them into the more readable "modern" text that you will find in such books as the Norton or Riverside Complete Works.
Dramaturgs are also the (often self-appointed) experts on the text of the play, as well as the Keepers of the Concept. If the director's goal is to use Twelfth Night to interrogate sexism in 1922 New York City, then the dramaturg is the director's eye in the sky, helping to make sure that there are no unintentional anachronisms, watching rehearsals and asking the difficult and frustrating questions that no one wants to hear, such as "does this scene really interrogate sexism, or does it encourage sexism?" and "how does the audience find out that Malvolio's sexist behavior is meant ironically?"
Inconvenient and abstract questions such as these, even when posed diplomatically, tend to make dramaturgs unpopular. Many directors would rather do without us and let the chips fall where they may. Who cares what the audience gets out of the play? The point is intention, not effect, right?
Er, WRONG. While it is perfectly fine for a director to take on the job of dramaturg (just like it is perfectly fine for a director to also be the lighting designer), SOMEONE has to think about the audience's response. Dramaturgs are sometimes separated into categories, such as "research dramaturg" and "production dramaturg." The first focuses on answering concrete questions about the text, while the second is more steeped in the abstract effects of theory and concept, but I would argue that both have to keep the audience in mind constantly. Whether I am deciding which lines we need and which lines we can cut, or if I am explaining my prediction that dimming the lights between scenes suggests a longer passage of time than leaving the lights on, those choices and suggestions always stem from my professional habit of putting myself in the audience's shoes. If I think we can't cut a certain line, it is because I think the audience needs the information, the wording, the characterization, the foreshadowing, or other ideas that this particular sentence conveys. One director's concept might need that line, while another director's concept might absolutely hinge on cutting that line out -- but only because of what that line would give to the audience, and how the director and I think that the audience will receive it. One interpretation of the play may need blackouts between scenes. Perhaps it could be a happy accident: we start out with blackouts as a purely utilitarian choice because we want to change the set between scenes, and then I (as the Eye in the Sky, watching the rehearsals) realize that the effect of increasing the apparent passage of time between scenes creates a tension that wasn't there before, such as the audience's awareness of just how long Orsino and Viola have had to become attached to one another. This passage of time could increase the audience's anticipation, their internal demand of "Oh, for goodness sake, just KISS her already!"
It is my personal opinion -- and I am aware that it is a controversial one -- that the difference between the professional artist and the amateur is that professional artists use their art to create a visible or otherwise demonstrable effect in their audiences. Art is Argument. Art is Activism. Art can start as self-expression (indeed, I think it should), but the difference lies in what happens next. Do you just speak your truth and leave it at that, or does it matter if anyone hears you? Does it matter how they respond? If they misunderstand, (such as the thousands of readers each year who think that Jonathan Swift really was arguing for institutionalized cannibalism in A Modest Proposal), does that misunderstanding aid your goals, or is it none of your concern?
I would like to fight back against the romantic image of the starving and misunderstood artist. I have known many artists who seemed to believe that the fewer people who "get" them, the better they are -- just like the complete myth that the fewer people who have heard of a band, the more esoteric those few audience members are. Over the decades, many artists and audience members have been complicit in creating and perpetuating a false dichotomy, a single spectrum upon which one end states: "Lost, Alone, Destitute, Unloved, Forgotten, and Disliked = Brilliant/Artistic/Talented" and the other end states: "Popular, Self-Sustaining, Wealthy, Famous, and Beloved = Sellout/Unartistic/Poser."
It doesn't take a psychologist to notice that this oversimplified notion (dismissing the audience's response) only really serves to satisfy unpopular artists that their ill-treatment by the masses is concrete evidence of their obvious genius.