True lovers of comedy revere irreverence. Just as melodrama was the natural voice of the 19th century, so comedy was the natural voice of the 20th. It was the age of screwball comedy and the sitcom, the Three Stooges and Didi and Gogo. It was also the age of the iconoclastic George Bernard Shaw. What else but a healthy dose of irony could have gotten us through a time defined by the undermining and shattering of revealed truths? Comedy dares to speak truth to power even when the emperor is naked - actually, especially when the emperor is naked.

The Shaw Festival's 2010 season focuses on comedies written between 1895 and 1944. Even a Canadian play from 2007 derives from a late Victorian novel by George Gissing. The plays almost dare you not to laugh this summer, while facing the fact that the truest comedy faces down the darkest truth. It hurts so much that only laughter can help. Those characters who are as naked as the emperor include most of the men and at least some of the women, but we're expected to take the women's side most of the time.

Many of the familiar names are on the list: Shaw, Oscar Wilde, Anton Chekhov, even J.M. Barrie. But the festival's coffers have to hope that a popular comedy like Mary Chase's "Harvey" will be the blockbuster that last season's "Born Yesterday" was. This gentle play about Elwood P. Dowd and the human-sized rabbit friend only he can see and hear asks little of an audience while offering the reassurance that what looks like madness is really only sweet innocence spiced with a pinch of shrewdness. When the comedy is sharp enough to cut through some of the sentimental malarkey, it can be endearing enough to make audiences happily suspend not merely disbelief, but any whiff of skepticism.

Wilde's "An Ideal Husband," back for the third revival at Shaw that I can remember, is the toughest of Wilde's four comedies. Its dialogue snaps with the playwright's characteristic bon mots, but its darker themes concern political integrity and compromise, as well as the claims of husbands and wives on one another within the sometimes-sacred bonds of marriage. This husband turns out to be imperfect - imperfection is always comedy's great lesson - and this wife has an opportunity to become less priggish than she sounds.

"Harvey" is pretty much a free ride for audiences, but "An Ideal Husband" challenges convention at most opportunities. So do Shaw's "The Doctor's Dilemma" and "John Bull's Other Island," along with Clare Booth Luce's acidic comedy of manners, "The Women," and Anton Chekhov's "The Cherry Orchard." "The Doctor's Dilemma" raises one of those moral conundrums in which Shaw always finds the human comedy at work. Who gets a life-saving cure, a kind physician who works with the poor or a talented but unscrupulous artist with a hot wife? Does the practice of medicine come with an overriding moral requirement, and is art ultimately worth anything when lives are at stake? Having raised the questions, Mr. Shaw gets busy.

The second play by Shaw (the festival seems determined to reduce the number of his plays to two after years of doing three) is one of my least favorite of his. Last year, I found the production of one of his funniest plays, "In Good King Charles' Golden Days," to be dishearteningly unfunny during one of the worst festival seasons I can remember. If the festival is back on track, I hope it can change my mind about "John Bull" and its Shavian take on the Irish.

So you expect Shaw to upend convention, but Chekhov does much the same thing with characteristic restraint and ambiguity as "The Cherry Orchard" watches over an aristocratic family whose way of life is disappearing. Will they have the gumption to survive, or have they so declined into passivity that they can only watch themselves evanesce? Irish playwright Tom Murphy has adapted the play and added what the festival calls an Irish twist. Certainly worth seeing, but with an arched eyebrow: if it ain't broke....

Meanwhile, "The Women" is everything "The Cherry Orchard" is not - sardonic, manipulative, and tough-minded. Not one of the women's promises is worth a damn, their claws are out, and every one of them has a scheme for getting, discarding, or stealing a nearby male. It's a very American play from 1936, one of the first to take this sharp-eyed a look at the 20th century's version of the war between the sexes, especially from the women's perspectives.

Finally, Kurt Weill's American musicals always deserve attention; they aren't revived all that often. His music is demanding and he was drawn to subjects that were difficult for musical comedy audiences to embrace. Once he had fled the Nazis in 1935, he had to learn how to write American; instead of Berthold Brecht, his collaborators now included Ira Gershwin and light verse master Ogden Nash. With Nash and librettist S.J. Perelman, he wrote "One Touch of Venus," based loosely on the story of Pygmalion and Galatea, but set in up-to-date Manhattan, circa 1943. It will be interesting to see if the book works a half-century later, but the songs are worth the price of admission - the standards "Speak Low" and "I'm a Stranger Here Myself," and my own favorite, "That's Him."

The rest of the plays: J.M. Barrie (of "Peter Pan" fame) provides the lunchtime fare of "Half an Hour," about another woman whose life is changing as everything whirls around her, and Linda Griffith's recent "Age of Arousal" is about three secretarial students in 1885 who confront what it means to be free of Victorian restraints. Only current playwright Caryl Churchill's "Serious Money" ignores the Shaw Festival's normal limits to go after the corporate raiders of the London stock market in the 1980's.