If the movies are any indication, being single has some pretty nasty side effects these days. In women, as Bridget Jones can attest, it's been known to cause bloating, moodiness, inability to put on a matching outfit, inability to properly apply makeup and, should a relationship ever occur, full blown dementia. In men, judging by Jude Law's uber cad in Alfie and the nearly deranged buddies Jack and Miles in Sideways, singleness appears to be a study in chain smoking, alcoholism, and pathological lying.

What is less expected, though, is that the book, written by Greg Behrendt and Liz Tuccillo, a former consultant and writer, respectively, on Sex and the City, turns out to be not just another guerilla dating guide but a surprisingly fascinating addition to the cultural canon of single, urban life. Post-feminist alarmism over single women's prospects began, arguably, with the now-debunked 1986 Harvard-Yale study asserting that a woman over 40 had a greater chance of being killed by a terrorist than of getting married, and reared up again in 1995 with the shrill husband-finding guide The Rules. But the genre found livelier footing on Sex and the City and He’s Just Not That Into You, which takes its premise from an episode of that program, has emerged as a new testament for the romantically unattached.

The book's popularity is less a function of its literary value--it's essentially an extended women's magazine article--than of the big, complicated question it poses (albeit indirectly) to single women: namely, in a world in which "there aren't that many good men around" –-in which Renee Zellweger's self-loathing Bridget Jones is the emblematic single woman—how does one find love while maintaining her dignity? To get at the answer, He's Just Not That Into You poses a series of more prosaic questions, along the lines of "why don't guys call when they say they will?" Contrary to popular female opinion (read: hopefulness), men who demonstrate less than total willingness to call constantly, ask for dates, discuss the future, and have frequent sex do so not because they're busy/shy/cautious/impotent but because they're "just not that into you." According to Behrendt, a self-described former cad who changed his ways only when he met the woman of his dreams, whom he married, "men would rather lose an arm out a city bus window than tell you "You're not the one."

An overstatement, perhaps, but brilliant in its simplicity. He's Just Not That Into You does for today's professional, urban women what The Rules did for marriage obsessed shrews (many of whom were also professional, urban women.) By reminding women how much men love a challenge—“we like not knowing if we can catch you,” writes Behrendt—it reconfigures passivity into empowerment. That may be an age-old romantic principle, but for the millions of women who, as Tuccillo writes, were "brought up to believe that hard work and good planning are the keys to making your dreams come true," sitting around and waiting to be asked out is hardly a natural inclination. After thirty years of automatically applying a hard driving, "you go, girl" edict to everything from corporate ladder climbing to dating, the collective release offered by He's Just Not That Into You may be the most exciting idea in years. Even Oprah Winfrey, whose September 28 segment on the book created such a sensation that it was largely unavailable for the ensuing weeks while the publisher rushed to print more copies, proclaimed it a tool of liberation.

Behrendt positions himself as a well-meaning older brother-"I'm a guy, I know how a guy thinks, feels, and acts, and it's my responsibility to tell you who we really are." But with his proselytizing braggadocio (funny the first 17 times, less funny the next 100) he's really more of faith healer ministering to the sufferings of women who cannot find Mr. Right because they continue to pursue men whose indifference, maltreatment, addictions or random excuses betray the fact that they're simply not interested in a serious relationship. The 41-year-old attractive, intelligent and never married Tuccillo functions as spiritual witness in Behrendt's camp meeting; thanks to his laying of hands, she's a hysteric miraculously made sane, a cripple who, in a moment of rapture, can suddenly walk (in Jimmy Choos, no less!) Amid Behrendt's take-no-prisoners didactisms—“the word ‘busy’ is a load of crap,” “if you have to be the aggressor, if you have to pursue, then nine time out of ten, he's just not that into you"—Tuccillo placates shell-shocked readers with sisterly testimonials. "Since I've been implementing Greg's handy-dandy 'he's just not that into you' philosophy I've been feeling surprisingly more powerful," she writes. "Because if men are asking you out . . . then you are the one in control."

That point is more a Homer Simpson-esque d'oh than an Oprah aha moment. The truth is, most women know deep down that asking out a guy is pretty much the equivalent of auditioning to be the understudy; you may get to play the part a few times but he probably has someone else in mind for the starring role. Most women also know that cheating is, like, a bad sign. But Behrendt and Tuccillo may have written the literary equivalent of bottled water. If nothing else, He's Just Not That Into You is an ingenious packaging strategy for an ostensibly abundant resource (basic human logic) whose purity has suddenly been called into question. And like a ubiquitous bottle of Arrowhead, the book seems to be in everyone's gym bag—let's just hope it doesn't spill out if Jude Law happens to walk by.

Handy-dandy philosophies aside, what's most telling about Behrendt and Tuccillo's concept is just how much its take on the single life reflects that of the rest of the culture. If the dazzling Sideways and the jaw droppingly formulaic Alfie have anything in common, it's their awareness that the mind and the heart are often destructively at odds. In these films, as in the Bridget Jones movies, we see men behaving badly and women getting hurt as a result. For both sexes, singleness is a club that seems to require no end of angst and hearthbreak in order to maintain active membership. Like Jack and Alfie and especially like Bridget, the single person is depicted as a chaotic person who drinks too much wine, eats too much ice cream, and, due to self-sabotaging romanticism, doesn't know what's good for him or her.

But regardless of how long He's Just Not Into You can maintain its yoga-like popularity ("please consider the glorious thought that he might just not be that into you. And then free yourself to go find the one that is," Tuccillo intones) it's possible that single people might be inching toward some kind of collective pride, albeit in exceedingly cheesy packaging. Even Bridget Jones, despite her usual string of humiliations, manages in her latest film to dispatch with the toxic Daniel Cleaver. And most of Alfie's women, for their parts, break up with him before suffering too many indignities. It's as if these characters have begun to absorb Behrendt and Tuccillo's overarching point, which is that it's better to be alone (possibly even forever) than stuck in a bad relationship. "My only job is to be as happy as I can be about my life . . . and to lead as full and eventful a life as I can," Tuccillo writes.

That's a pretty revolutionary statement in a society so deeply rooted in monogamous couplehood and nuclear families. And therein lies the undercurrent of radicalism beneath the bright pink jacket and quippy one-liners. He's Just Not That Into You is dark at times, and it may be this startling honesty, this overdue recognition of the unfairness of life and the mysterious, illogical ways of the heart, that draws so many women to the book. "I think some of those people who are single and ready to have love in their lives are going to get cancer and die," admits Tuccillo, "or get hit by a car, or just never find love with a good man and maybe just settle." (Behrendt on this issue: "I believe life is a speedy and awesome gift, so don't waste the pretty.")

Uh, okay. Whatever there is to be made of this, the delicious irony of He's Just Not That Into You is the fact that most of what's smart about it seems to be purely accidental. Despite its guise as a dating manual and its earnest attempt to help women find men who are into them, the book is ultimately a sneak attack against the conventional tactics of modern dating, a disavowal of the snare-a-guy-at-any-cost mentality generated by decades of "man shortage" hyperbole. That might not sound like a formula for selling millions of copies until you consider that U.S. Census figures released last week show that nearly a quarter of women and a third of men remain never married by the age of 34, a four-fold increase from 1970. So it makes sense that the best dating guide for this population is an anti-dating guide. At the very least, it gives women something new to overanalyze over Martinis and spring rolls. Men, for their part, can thank Behrendt for doing the dirty work that might otherwise cost them their arms out of city bus windows. We can all be grateful for that.