When a writer kicks up enough dust to invite attack from every direction, she must be doing something right. So argues Craig Seligman, at least, in his smart, engagingly written, provokingly partisan tribute to Pauline Kael and Susan Sontagówhich is fitting, since his subjects helped establish the proposition as a critical truism. It's a fascinating idea to pair these two women, who once seemed like opposites but who can be viewed, forty years after their dramatic arrival on the scene, as a kind of odd-couple tag team, introducing radically transformative definitions of joy and moral seriousness to American culture in the '60s and '70s. Sontag and Kael accomplished more than this, of course. Seligman's deferential use of their last names in his title, an honor usually (and unfairly) reserved for men, captures the unique reputation they still enjoy as Amazonsócritics who've stood taller, withstood more slings and arrows, and captured more prey than their peers or their successors.

Seligman gets good mileage simply by retracing the basic arcs of their careers, and comparing. Biographically, the similarities between the two are striking. Both were Jewish and hailed from the West (Kael was born on a chicken ranch north of San Francisco and grew up in the Bay Area; Sontag was born in New York but raised in Tucson and LA). In college, both majored in philosophy. Later, both partnered with a man, then split up and bravely raised a child alone. Perhaps acting out the challenge of being an outspoken woman just before feminism hit its stride, both also developed a persona of resolute toughness, not much given to introspection, and seemed at times to look down on anything that might be construed as soft.

Their differences, of course, were obvious. Seligman reminds us that Kael was older when she established herself: thirty-three when she published her first film review and nearing fifty when she landed at the New Yorker in 1967. Her zippy prose sounded youthful, but maturity and a skeptical temperament imbued her writing with a wry and healthy appreciation of life experience. Once she settled into them, her bullshit-slaying mission and her deceptively conversational tone (a hard-won literary effect, Seligman rightly points out) barely changed over the next three decades. Sontag, by contrast, sprang from the gates as a prodigy and neurotically devoted herself to improving, discarding, trying out different styles and theories, and reversing some of her most passionately argued political positions. She sympathized with the North Vietnamese in 1968 but with Poland's Solidarity Movement in 1982; her antinarrative fiction in the '60s has given way to great gushes of romantic prose in recent novels; she took humanism to task in Against Interpretation, but these days she tends to argue for humanism above all else. Their biggest differences were aesthetic, and enormous. Kael was hilarious, Sontag, to put it mildly, not. Sontag has tended to mistrust art that's vulgarly popular, arguing early on that it was sometimes the correct choice for an artist to bore the audience. Kael didn't exactly embrace vulgarity to the degree her critics charged, but she refused to praise art with high aspirations if it didn't first of all engage. "If art isn't entertainment, then what is it?" Seligman quotes her quipping in an interview. "Punishment?" (It's fun to hear that voice again.)

I revere Sontag. I love Kael," Seligman declares. He is forthcoming about his personal friendship with Kael, writes movingly of spending time with her in later years, and admits to forgiving her such peccadilloes as occasional unfairness and lapses in taste. On Sontag he is tougher. He shrewdly defends her prose against the charge of dryness, calling it "as colorless, as odorless, as tasteless, and as intoxicating as vodka." But he cringes at her squareness and at the "exclusionary malevolence" of her restless taste-making. As he neatly puts it, Sontag "came to resemble one of those travel insiders who's anxious to reach the pristine beach before the tourist hordes find out about it." Still, he argues that she has earned our admiration for her fearlessness and for trying so hard to be true.

Having presented his own rather nuanced views (full disclosure: I first learned he was a sharp reader when he edited my brief movie reviews several years ago in the New Yorker), Seligman gets to work defending Kael and Sontag from the complaints of others. This is quite a job. From her crushing put-down of Andrew Sarris's auteur theory to her iconoclastic thesis that Orson Welles took too much credit for the writing of Citizen Kane to her dismissive 1985 review of Shoah, Kael has been accused of a flippancy that lowered standards as well as unsavory bullyingómost famously by Renata Adler, in an unfair, half-mad, but still insightful 1980 attack in the New York Review of Books. Sontag's early essays on camp and the "new sensibility" struck some of her contemporaries as frivolous and irresponsible; later, with her famous activism around causes, the charge generally shifted to pretension and moral ambition. And, of course, she ticked off the Right with her hysterically denounced post­September 11 statement in the New Yorker, in which she called for a more grown-up response to the disaster and weirdly forgot to grieve. Seligman is wiseóangry but ambivalentówhen he defends both from charges of old-guard attitudes toward homosexuality. (He wishes Sontag had come more demonstratively out of the closet.) Writing on his own behalf, he also concedes that Sontag and Kael "enraged people. And they loved doing it, though neither one ever copped to (or, I suspect, recognized) the extent of her pleasure. While some of this anger can be written off to misogyny, that's a charge I hesitate to level indiscriminately. Their pugnacity, their self-assurance begged for a fight." If this is so, though, Seligman's response to those who've fought back over the years is not very sporting. He characterizes various detractors as "turf-guarding insiders" and finds others guilty of "raving," "malarkey," and "question-free, doubt-free boosterism." The volley of counteraccusations tends to make right-wing enforcers and PC complainers blur in our minds with those who have had legitimate intellectual bones to pickóand more in this last category probably won their quarrels than he allows.

Something is at work here: At a few points, Seligman seems to drop his fine-tuned critical apparatus and merge with the consciousness of his domineering heroines. In describing the intense experience of reading their prose, he borrows Sontagian and Kaelesque notions: "your intellect responds to their writing in a manner that's so overpowering, so encompassing, and so concentrated that it's like an erotic experience." At another point he makes the casually brilliant observation that "Kael is the rare (literary) example of the untroubled consciousness." How crucially true of her this seems. She wrote without a sense of guilt, as so few critics doóshe was uniquely free. But then he goes on: "Her sentences get their nervous agitation not from self-doubt, of which she had none, but from impatience, the arguer's impatience with those who don't get it." Those italics at the end raise the possibility, which Seligman doesn't seem to mind, that the burden of guilt hasn't disappearedóit just got transferred to readers who can't see the light.

This is a personal book, and it invites personal reactions. As delightfully as Seligman makes his affirmative case for Kael and Sontag's irreplaceability, by the end he got me thinking about ways in which a critic of today might not want to emulate them. Kael formed her sensibility at a time when Hollywood still churned out message pictures and patted itself on the back, and many of her colleagues could be relied on to praise their shallow civic worthiness. The smug consensus she fought against, and the vast mass culture that bubbled beneath it, have been replaced by the painful chaos of red versus blue; acrimony, not complacency, is the default cultural setting; and her groundbreaking celebration of beautiful throwaway moments in otherwise negligible works has been assimilated to the point of cliché. The milieu that lent urgency to Sontag's earliest writingówhich Seligman argues is her bestóis gone, too. Artists hardly seem ahead of everyone else, as Sontag could once (pretentiously but plausibly) claim, in giving form to people's experience of the world.

What to do, then? I confess to having few ideas beyond continuing to challenge, as Sontag and Kael did for their time, the accepted notions of what makes a great critic. Are combat and ravishing sex the best metaphors for what's needed? Is apostasy the right way to go? Might today's aspiring young critic spend a little less energy on impatience with those who fail to get it? That could be liberating, for startersóand thus another way of paying tribute.

Sarah Kerr is film critic for Vogue.