Watch. Think. Squirm.

It was the door slam that sent tremors throughout Europe, and eventually America too. Four days before Christmas 1879 in the Royal Theater in Copenhagen, the first audience for “A Doll’s House” watched Ibsen’s Nora take her leave of husband, home and hearth. And they were shocked.

Not only had they just seen a bourgeois wife do the unthinkable, they’d also borne witness to what has been called “the birth of modern drama.” As George Bernard Shaw wrote, “Nora’s revolt is the end of a chapter in human history.”

Although “A Doll’s House” still has the power to upset, it generally requires more than Nora’s exit to rattle an audience. Now it takes a successful, seemingly happily married man who is having a passionate affair with a goat, as in Edward Albee’s “The Goat, or Who Is Sylvia?” which opens at the Taper today.

“The Goat” premiered on Broadway in 2002 to equivocal reviews that reflected the ambivalence of some theatergoers. It went on to win the Tony for best new play. But as the initial reaction proved, more than a century after Nora took her leave, the theater still has the power to shock. And many of today’s leading playwrights continue to wrestle with the notion of unsettling their audiences.

Although Albee, the author of such works as “The American Dream,” “Who’s Afraid of Virginia Woolf?” and “Tiny Alice,” has been shocking people for decades, he insists it’s not his goal.

“I don’t sit down and say, ‘Now, how can I shock an audience?’ ” says the 76-year-old playwright. “I’m not out to be provocative for the sake of provocation only. I write my plays to find out why I’m writing them. Some of my concerns will be troubling.”

Albee isn’t the only one taking risks. In recent years, heated debate has been stirred by some of the serious mainstream theater’s most respected artists, including Terrence McNally, Tony Kushner and Suzan-Lori Parks. In addition, works by Paula Vogel, Eve Ensler, Patrick Marber, Christopher Shinn and others have tackled taboos, ranging from domestic abuse to incest as well as troubling behaviors and psychology.

Whether intended or not, plays can still inflame emotions, as happened with McNally’s “Corpus Christi.” In 1998, the Manhattan Theatre Club announced it was canceling its planned presentation of the play, which features a gay Christ-like figure, after receiving violent threats. The decision was quickly reversed, and the play drew fire from the Catholic League before opening amid protests in fall of that year. And the offstage drama didn’t stop there: As recently as 2001, a group of 21 Indiana legislators and 11 citizens filed suit to stop a student production of the play at Indiana University-Purdue University Fort Wayne.

“I certainly did not expect ‘Corpus Christi’ to arouse the kind of furor that it did,” McNally says. “I don’t think people were shocked that you could tell the story of Christ with gay men. I think they were whipped up into frenzy by political and social forces. You wonder how many fundamentalist Christians saw the piece, although they stood outside.”

Most often, people register their protests by walking out, as they did during the New York run of “The Goat.” “I was a little shocked by some of the outrage,” says Albee, who sees his play as an open-ended inquiry into contemporary values. “If you press certain buttons, people are going to do a knee-jerk reaction.

“If you write something easy, you can come up with answers. I have many more questions than I have answers. I think that’s my job.”

The eye of the beholder

Is it the proper province of the theater to shock? Says “Angels in America” author Kushner: “When art shocks because it dares to articulate that which is true but forbidden public expression, or when it shocks because it forces recognition of some truth we’ve repressed, or shocks because something new is being articulated and it freaks us out, it’s doing what it’s supposed to do.”

Clearly, “The Goat” is a play that dares. But the “truth” of the drama is subject to interpretation. “Shock is in the eye of the beholder,” says McNally. “You never know what’s going to shock an audience -- to ‘disturb’ is a better word.”

Like “A Doll’s House” and “Who’s Afraid of Virginia Woolf?” “The Goat” is a dissection of a marriage. Martin is a renowned architect who, just shy of his 50th birthday, has been awarded the Pritzker Prize and a major commission. He is married to Stevie, with whom he appears to have that “true marriage” of equals that eluded Nora. But it all falls apart when Martin confides to his best friend that he has fallen passionately in love with Sylvia, a goat.

As if the goat affair weren’t enough, there’s a scene in which the family’s openly gay son kisses the father. Albee notes, not without irony, that that was the point at which people tended to walk out -- not during the much earlier revelation about sex with the goat.

From the playwright’s point of view, the subject of his play is “the arbitrary limits of our tolerance.” Albee, a three-time Pulitzer Prize winner, argues that “we should really examine our values to see what we really believe. I’m convinced that the willingness to examine them will rid most of the problems in our values. In the case of ‘The Goat,’ I wanted them to imagine how they would respond if they themselves were in such a situation. And there are probably many worse things than having intercourse with an animal -- complacency, mendacity.”

Yet even in the hands of a masterful dramatist, trying to control an audience’s response is problematic. “A play that is just going to be shocking is not going to attract a thinking audience,” McNally says. “Was it Ibsen’s intention? My intention was not to shock but to maybe make people rethink something they probably have preconceived notions of.”

But there’s a thin line between stimulation and shock. “When an audience is shocked, maybe they’re not hearing what you’d like them to hear, because they’re in a place of indignation,” McNally suggests. “It’s hard to find the balance. What you want to do is keep an audience there with an open mind and heart.”

One play that drew large audiences despite having confrontational elements was “Angels in America.” “Some people are shocked by the sex scene in the park in Part 1,” Kushner says. “And some are just shocked to see so many homos on stage. But I didn’t write the play with the intention of shocking those too-easily-shocked people. Maybe the most shocking thing about ‘Angels’ is that it had such a big success.”

Still, playwrights like Kushner must strike an artful balance. “I like to be surprising, unexpected. I wouldn’t want people to see my plays and say, ‘Oh, not that again.’ But surprising people is a way of giving delight and pricking attention and making the familiar seem unfamiliar or vice versa -- that’s not the same as shocking people,” he says. “I’d rather feel that I had given people a complicated and rich and contradictory experience, large and provocative -- by which I mean generative of questions about difficult conundrums, generative of useful, fertile discussion, thought, vision, dreams.”

Theater that confronts

Did it start when Oedipus slept with his mother? Or when Medea killed her children? No matter where you pinpoint the origin, the sometimes disquieting examination of social structures and values has been an important function of theater at least since the Greeks.

Indeed, “The Goat” evokes the Greeks in several ways, including its subtitle: “Notes toward a definition of tragedy.” Moreover, the Greeks called their tragedies “goat songs,” because the animals were given as prizes or sacrificed there.

The Greeks, Shakespeare and Ibsen, among others, knew that didacticism alone was seldom convincing. “ ‘Oedipus Rex’ is unsettling, but you don’t feel you’re being lectured,” McNally says. “There are very shocking moments in Shakespeare; ‘King Lear’ is filled with shocking moments, and what it has to say about humanity is shocking and awesome.

“I think the perfect example is ‘A Doll’s House.’ It doesn’t seem to be a polemic and yet it still upsets people. Ibsen puts his finger on something very uncomfortable in the battle between the sexes. I think that play has a resonance for all people, whereas contemporary drama that may be shocking is more limited.”

American theater has no consistent history of confrontational theater, although it’s been more prevalent in times of heightened politicization, such as the 1930s and ‘60s. But even in conservative decades, a play will come along that is both a milestone and a shocker.

“In our time, I think ‘Death of a Salesman’ is the best play that upsets, provokes, shocks and yet is welcoming,” McNally says of the Arthur Miller classic given its premiere in 1949.

In the ‘50s, there was a great deal of provocative, often avant-garde theater in Europe, from Genet and Ionesco to Harold Pinter and Britain’s Angry Young Men.

It was not until the ‘60s that American theater saw a sudden upsurge in theater that shocked, from groups such as the Living Theatre and writers such as Albee.

When Albee’s “Who’s Afraid of Virginia Woolf?” premiered in 1962, its searing portrait of a marriage startled some theatergoers. “People would come up to me and say, ‘How dare you say such things onstage?’ ” the playwright recalls. “And they would tell me things that weren’t in the play -- not language, but ideas.”

In the late ‘60s, the revue “Oh! Calcutta!” the musical “Hair” and other shows shocked with their extensive use of nudity. Today, nudity seldom shocks. In fact, smaller shows such as “Naked Boys Singing” and “Puppetry of the Penis” use nudity merely as a gimmick.

Used with more serious artist intent, however, nudity can still provoke debate. “Of course we’ve been through the nudity wars. Why is it not shocking to see a nude in a museum, but a naked man live is? That’s one of the things I wrote about in ‘The Stendhal Syndrome,’ ” McNally says, referring to a pair of one-act works -- “Full Frontal Nudity” and “Prelude and Liebestod” -- presented at Primary Stages in New York last year.

In the decades since Nora’s first exit, sex and violence in TV and film have made it harder for the theater to shock. “Personally, I often find TV more shocking than theater,” says Kushner. But “maybe people remark more when a play shocks because people have sort of decided that theater has no effect whatsoever, most of the time, and they’re shocked to find it shocking.”

Cost and conviction

Ultimately, “The Goat” may be shocking simply because it dares to disturb -- a rare occurrence in today’s mainstream theater. “Maybe it’s gotten less dangerous, people seem to think that’s the case,” Kushner says. “Maybe it’s less interested in troublemaking than it used to be, though there’s a great deal of work being done that’s deeply serious, opposed to the political evils with which our democracy is currently afflicted, willing to say unpopular things, even if it risks shocking people.”

The majority of that serious work, however, is produced far from Broadway, in regional and smaller theaters.

Probably the most powerful factor mitigating in favor of the commercial theater’s conservative aesthetics is cost. It simply takes more -- in real dollars -- to produce a show today, and most don’t make money.

“It’s so preposterously expensive that people are reluctant to provoke,” Albee says. “Now you lose your shirt, so they’re more cautious.”

Then too, there is the audience.

“Most audiences don’t like to be upset,” Albee says. “I’ve never understood why people will pay $100 and have nothing happen to them, and I’m talking about the Broadway musicals now. People will pay anything for a waste of time.”

The greater issue is the proper role of theater in society. Should it confront and challenge, or is it there primarily to entertain?

“Too many people think that the arts should be a servant of the audience rather than the educator,” Albee says. “By giving the audience what they think it wants, they end up constantly lowering the common denominator of taste.

“I’m not saying it isn’t fun to upset people, but I never do it just for the fun of it. If you open your mouth, you take your chances.”

*

‘The Goat, or Who Is Sylvia?’

Where: Mark Taper Forum, 135 N. Grand Ave., Los Angeles

When: Opens 4 p.m. today. Runs 8 p.m. Tuesdays through Fridays, 2:30 and 8 p.m. Saturdays, 2:30 and 7:30 p.m. Sundays.

Ends: March 20

Price: $34 to $52

Contact: (213) 628-2772; www.MarkTaperForum.org