The critic Lee Siegel has embarked on an unenviable venture: challenging the pieties of contemporary Internet culture. In Mr. Siegel’s rendering, the Internet promotes a form of cultural obesity – its vastness, often heralded as an unparalleled good, now threatens our intellectual health. Journalists and critics who should approach this new medium with healthy skepticism instead kowtow to the latest online trend, aiding and abetting the public in its uncritical embrace of technology. With the controversialist’s eye for compelling anecdote and the polemicist’s art of generalization, Mr. Siegel makes a bracing case against the techno-triumphalism he sees rampant in our culture. “Things don’t have to be the way they are,” Mr. Siegel writes in “Against the Machine” (Spiegel & Grau, 192 pages, $22.95), and his book is an extended argument about the costs of elevating electronic convenience and control at the expense of critical judgment.

Although broad-ranging in his approach, Mr. Siegel frequently returns to three themes: the Internet’s relationship to democracy; the Internet’s erosion of standards and expertise, and the Internet’s role in the commodification of private life. “Criticize the Internet and you are accused of criticizing democracy,” Mr. Siegel writes. This is not entirely hyperbole: The largely unchallenged narrative about the Internet is that it fosters free speech and vigorous, if at times vitriolic, discussions among citizens of the Web — in other words, it encourages healthy democratic debate. Mr. Siegel sees something else. “Internet users generally … and bloggers especially inhabit an absolutely solitary space in which other people exist as stick figures filled out by the user’s or blogger’s conception of them,” he writes. “That’s why virulent hatred comes so easily.”

But if Mr. Siegel’s claims about the Internet’s antidemocratic tendencies are at times overblown (he coined the term “blogofascism”), he is correct that the blogosphere is as adept at drawing out the worst tendencies in a democracy as it is of fostering the good ones. His discussion of the blogosphere’s attitude towards the mainstream media illustrates the point; the ballyhoo about “citizen journalists” storming the Bastille of established journalistic institutions has not materialized. In fact, most Web logs are an extended commentary and conversation about the news produced by those institutions, not a qualitative challenge to them. “You really have to marvel at how the blogosphere has turned a quintessential product of democracy like the American newspaper into an obstruction of democracy,” Mr. Siegel writes.

Mr. Siegel is also an adamant defender of the need for expertise against the claims of bloggers who see it as a form of elitism or privilege. “Professions and trades require training,” Mr. Siegel writes, and this is no less true for journalists than for other professionals. No one, he reminds us, is eager to engage the services of “citizen heart surgeons.” Not surprisingly, Mr. Siegel is especially exorcised by the loss of authority of the cultural critic; like travel agents, critics have seen their business severely compromised by the Internet. Yet the passenger who conveniently purchased his ticket online is often dismayed to find that he has no reliable advocate to intervene with the airline when his flight is suddenly cancelled. So, too, our culture’s embrace of the everyman critic risks leaving us bereft of standards for measuring the quality of music, art, and literature — aside from the popularity demonstrated by page hits or Amazon rankings.

As the example of the online encyclopedia Wikipedia shows, amateur insights offer us enormous convenience and heterogeneity of opinion; but these often come at the expense of reliability and objectivity. Enthusiasts of Wikipedia claim they are “democratizing knowledge.” Mr. Siegel argues that in fact their work is an example of the broad confusion of information with knowledge — a confusion that characterizes much of online culture.

Similarly, Mr. Siegel finds little to savor in the melee of self-expression fostered by the participatory Web – often called Web 2.0. For Mr. Siegel, Web 2.0 — which includes social networking sites such as MySpace and video-sharing sites such as YouTube — is less a pageant of democratic genius than a vast experiment in self-marketing. “The Internet’s vision of ‘consumers’ as ‘producers’ has turned inner life into an advanced type of commodity,” he writes. In this environment, he wonders, “How do we keep an obsession with the bottom line from overwhelming our lives? How do we carve out a space for a life apart from the Internet, and apart from economics?” More important, by commodifying personal experience we risk losing the distinction between art and self-expression. Art, Mr. Siegel reminds us, “speaks to us even though it doesn’t know we’re there.”

As with any polemic, Mr. Siegel’s book raises many more questions than it answers. He notes that he is interested in exploring “patterns of behavior created by the Internet itself, problems spawned by the Internet’s everyday routines,” for example, yet he rarely goes further than describing some of the more extreme examples of these behavioral patterns. His argument would have benefited from acknowledging that there is still a great deal we don’t know about the Internet’s effect on behavior. The social science and behavioral research now being done will be critical for helping us understand how the Internet is changing us, for good and for ill – particularly for younger generations. Will a congenital digital credulousness be the hallmark of their worldview? Or will their early immersion in Internet culture have more positive effects?

“Against the Machine” is a necessary book; Mr. Siegel’s willingness to perform the difficult (and unpopular) work of cultural criticism on so vast and disparate an entity as the Internet is admirable. To be sure, he is not always a genial guide. He is merciless in his criticism of journalists whom he feels are too sympathetic to Internet culture, and impatient with writers who would see the Internet for its opportunities rather than its dangers. But impatience can be a virtue. Mr. Siegel’s animus toward the “electronic mob” and his excesses of tone are forgivable when viewed against the overheated techno-enthusiasm of contemporary culture. By reminding us of Spinoza’s insight — “All things excellent are both difficult and rare” — Mr. Siegel challenges us to consider the great costs to our culture and our humanity when we embrace a technology that instead makes everything merely easy and common.

Ms. Rosen is a fellow at the Ethics & Public Policy Center in Washington, D.C., and senior editor of the New Atlantis: A Journal of Technology & Society.