It’s only natural for a decadent age to produce nostalgic entertainments invoking a world of lost innocence. But what does it say about the current state of our current pop culture when one of the biggest Hollywood studios (Twentieth Century Fox) invests a bundle for a glossy, nostalgic comedy paying tribute to a long ago world of false innocence?

“Down With Love,” the heavily hyped new star vehicle for Renée Zellweger and Ewan McGregor, is supposed to take us back to the carefree universe of Rock Hudson-Doris Day romantic comedies of the late ‘50’s and early ‘60’s, including “Pillow Talk,” “Lover Come Back,” and “Send Me No Flowers.” At the time, these silly but successful films carried a reputation as sophisticated, racy, even naughty -- full of sly references to sex and pursuit, even though the heroines never surrendered their virginity outside of marriage. I specifically remember wanting to see “Pillow Talk” when it came out in 1959, but my late mother wisely vetoed that idea -- insisting that such an “adult” farce would be completely inappropriate for a ten year old. If anything, the intervening years have only diminished the highly polished, Technicolor luster of the Hudson-Day comedies. First, Doris Day went public with the depressing details of her life off-screen -- indicating that Hollywood’s perky and perennial virgin actually went through a long series of irresponsible, abusive and profoundly painful sexual relationships. Then, of course, Rock Hudson died of AIDS, with attendant attention to his long-standing and aggressive homosexuality.

In this context, the Hudson-Day comedies look more like painfully dated cultural curiosities today, rather than the “classics of a golden age” – as heralded in the promotional materials for “Down With Love.” In fact, one of the most surprising aspects of this new project is that savvy producers (including the creators of the Oscar-winning “American Beauty”) decided to make it at all. The other shock is that the fluffy, ridiculous result, despite decidedly questionable casting, proves oddly enjoyable in its amiable and unapologetic artificiality.

Renée Zellweger plays an implausibly fashionable country girl from Maine who’s come to New York City in 1962 for the publication of her first book, “Down With Love.” That literary endeavor, complete with a provocative pink pastel cover, urges women to concentrate on careers rather than marriage, and to follow the male example of indulging in casual sex without commitment. The stuffy, all-male executives at the publishing house (complete with horned-rim glasses, pensive pipes and narrow ties) don’t understand the appeal of the book, but Zellweger’s spunky editor (Sarah Paulson) fights to place the controversial title on the bestseller list.

Suddenly, “Down With Love” girls turn up everywhere, declaring their independence of domineering males, so that the sexist establishment must counterattack. Leading that effort to restore order and traditionalism is the famous investigative reporter, Catcher Block (Ewan Macgregor), a dashing James Bond type (complete with tuxedos and British accent) who will go to elaborate lengths to force the best-selling author to violate her own principles by falling  in love with him. To accomplish this purpose, he impersonates an astronaut, and puts on a Texas accent that makes him sound eerily like Matthew McConaughey. Meanwhile, the star journalist’s magazine publisher, David Hyde Pierce, nurses a desperate crush on Zellweger’s editor, but can’t betray the secret agenda of his most important reporter.