So often these days, the Founding Fathers get held up as paragons, possessed of a singular, even freakish merit. Yet if you visit the John Adams homestead in Braintree, Massachusetts, you can picture America's second president as a mere boy in his milieu, decades before greatness, imbibing certain shared assumptions about the procedures of everyday public life. A tour guide will lead you into the snug parlor of a low-ceilinged saltbox, and after some remarks about what's original in the structure and how the chunky hearth once functioned as kitchen and winter furnace, he will point with unexpected pride to a straight-backed chair. A frequent sight for Adams while he was growing up would have been townsmen gathered around it for meetings led by his father, who was a deacon and selectman.

These people held meetings. Long before the first inkling of independence, they had developed the habits of volunteering, delegating, arguing toward the goal of joint problem solving. In On Revolution (1963), Hannah Arendt praised this early, confident relish for the public sphere, this "public happiness," which she thought might be America's luckiest inheritance. But she worried about the ways in which the country seemed inclined to squander it. Americans tended to confuse freedom with free enterprise, she fretted; we were suckers for positive PR; we allowed our leaders to drift from reality and rename their failure a success. This is just one of the strains of Arendt's thought that might, in theory, speak to us now—in what seem by general agreement to be darkish times. But if the wider range of her ideas could speak again, how much and what exactly would we hear? What would the pioneering anatomist of "total terror," who hated for words to be used like weapons in a fight, make of the rallying cry Islamofascist? Could a reading of Arendt point the way forward to any positive, concrete actions people might take to safeguard freedom while keeping safe? Or would she, if she were here, simply get to work describing the shape of a new abyss?

Arendt's conceptual daring has been the object of admiring awe, but also of intense pro-and-con partisanship, for over a half century. First, of course, came The Origins of Totalitarianism (1951). Having fled Germany in 1933 at the age of twenty-seven, and later Paris, after internment in southern France, Arendt arrived as a refugee in New York and spent eight years researching a book that would eventually, through much revision in dialogue with unfolding world events, yoke the regimes of Hitler and Stalin together to illuminate the ghastly new form of government they had in common. Today, scholars agree that Arendt wasn't the first to use the term totalitarian or to compare the two seemingly opposite systems. But her study's momentous flow of provocative assertions and its bewildering yet somehow literarily skillful juxtaposition of abstraction with the starkest facts fixed the idea in readers' memories. Thereafter, Arendt moved intermittently among New York intellectuals and continued to blur categories that had hitherto been seen as opposed. She was a philosopher who offered notes on the very latest world affairs; she was a sometimes-obscure, elitist champion of political freedom.

Thus was the reputation established. Over the years, more layers were added to it. First, with Eichmann in Jerusalem (1963), her report on the trial of mass-murdering Nazi bureaucrat Adolf Eichmann, Arendt opened up for exploration issues, such as the bearing of witness in the Holocaust and the immense difficulty of prosecuting crimes against humanity, that still feel raw and relevant today, while distressing critics who were able to identify a range of factual errors in her account and who believed she exaggerated the culpability of Jewish leaders in the Shoah. Controversy over this great judge's judgment extended until well after her death in 1976, with the slowly emerging understanding that she had had a youthful love affair with her teacher Martin Heidegger, the German philosopher of Being who rose to university chancellorship under the Nazis from 1933 to 1934 and afterward never adequately reckoned with his past.

In her later work, Arendt continued to surprise. Jonathan Schell relates in a new introduction to On Revolution how much Arendt was inspired to hope again by the example of the quashed 1956 Hungarian uprising. Here, once more, she went against the grain, finding possibility in what had seemed, politically speaking, an obvious cause for despair. But the democratic turn in the late 1980s of societies from the Philippines to South Africa, Poland, Chile, and Czechoslovakia seemed to bear out her prescience about the kind of affirmative, spontaneously arising power of self-organizing citizens that might be tyranny's Achilles' heel. The peerer into the twentieth-century void would over time become an inspiring framer of challenges for those engaged in rethinking political ethics and human rights and in thinking the young but burgeoning field of international law.

October 14 would have been the philosopher's hundredth birthday. Centenary conferences have been held at Yale and Bard and also in Berlin, where, close to the Brandenburg Gate and the Holocaust Memorial, a street has been named after her. Penguin Classics has put out new paperbacks of Eichmann in Jerusalem, On Revolution, and Between Past and Future (1961), with prefaces by, respectively, Amos Elon, Schell, and Jerome Kohn, Arendt's literary executor as well as the editor of several collections of her essays. But the most direct brief for Arendt's relevance comes from Elisabeth Young-Bruehl, a student of the philosopher at the New School starting in 1968 and later the author of the major biography Hannah Arendt: For Love of the World (1982). (She's also a psychoanalyst and a biographer of Anna Freud.) Now, for the general audience and addressing the post-globalization-triumphalist, post-9/11, post-Guantánamo mess, Young-Bruehl has written a sympathetic, deeply versed, yet highly accessible (if sometimes a bit too earnest) guide, Why Arendt Matters, in which she hopes to "show how Arendt thought and how she arrived at the judgments she made about her era, the era of totalitarianisms and their sequels, which she called 'the modern world.'"

But before she can get to the Arendt whom she wants to matter more, Young-Bruehl has to touch quickly on the two controversies that may have hit their peaks but still have life left in them. Arendt "lives on in newspeak through just four words," she notes on the first page. The media's promiscuous overuse of the phrase "the banality of evil," from Eichmann in Jerusalem, has turned it into an unhelpful cliché, she writes. Young-Bruehl directs us back to the philosophical problem of evil, a discussion begun two centuries earlier by Immanuel Kant that Arendt saw herself as extending. Arendt was not arguing, as many of her readers have concluded, that there is a bit of Eichmann in everyone. Instead, it had struck her as a significant and new phenomenon that at no point in his execution of grotesque policy did it enter his mind to "think through the question that [she] considered essential to moral experience, one that she (very provocatively) held was not at all a matter of following rules: ‘Could I live with myself if I did this deed?'"

This last point leads, in a roundabout way, to the second sore spot, Heidegger. Young-Bruehl believes that it may in fact have been Arendt's reaction to their affair, once it had ended, that prompted her to search for the "cure to her own youthful unworldliness." To think through things with a greater eye to their consequences in the world became Arendt's more conscious intent around the age of twenty-five, Young-Bruehl writes, a goal further supported by studies with the philosopher Karl Jaspers and through her marriage
to the independent-minded communist Heinrich Blücher.

Why Arendt Matters is of necessity a fast-moving and somewhat surface-skimming book: There are vast mountain ranges of philosophy, history, and hotly argued current events to survey in 240 pages. The book is divided into a discussion of three of Arendt's works: Origins; her 1958 philosophical inquiry The Human Condition, which Young-Bruehl calls a "primer on how to think about and evaluate the res publica; the public things"; and her last work, The Life of the Mind, in which Young-Bruehl locates Arendt's further turning away from Heidegger's philosophy—but also, more important for Young-Bruehl's purpose, Arendt's lasting statements about thinking and freedom.

Instead of a straight summary or a logically accumulating argument, Young-Bruehl has written something closer to the monologue of a personable teacher who darts around the room while she talks, letting associations flow. "We cannot use concepts from Before," she offers early on in the book as one of Arendt's major lessons, "inherited from a world that exists no longer, to explore the After." With the modernists, Arendt believed a fundamental gap had opened in human history. She was passionately on the hunt for obscuring clichés that failed to acknowledge the change. Much of her work is intended to correct the use of outdated terms to describe something recent, as well as the sloppy borrowing of terms from the wrong category. Authority is not the same thing as power, she explained, and power is not the same thing as violence. Young-Bruehl aptly points out that with her highly personal drive to perceive and communicate what is novel, Arendt tended to think in a way we usually associate with artists: "Hannah Arendt was that rare being: a thinker of poetic capacity and devotion who was not a poet but was, rather, an analyst, a practical-minded person who used distinction making to break things down into their component parts and show how they worked."

Young-Bruehl has distilled her long immersion in Arendt into an old, comfortable familiarity. She can discuss abstruse Arendtisms the way people can describe a hidden cubbyhole in the house they grew up in. Usefully, she reminds us of the less discussed "Imperialism" section of the Origins of Totalitarianism. It was part of Arendt's sometimes-eccentric method never to argue anything so simple as "x was the cause of y." But she did imply a kind of blowback factor whereby nineteenth-century racism and thoughtlessly engineered movements of populations had helped seed the ground upon which modern monsters walked, rebounding "on the imperialists as the colonialists transmitted back to the state their ethic of ruthlessness." This brings to mind the argument by some proponents of the War on Terror that you have to choose what to seek to understand—either imperialism or totalitarianism. Arendt didn't see it that way.

Young-Bruehl is also instructive on how often, and how often surprisingly, Arendt's thought evolved. But this very sensitivity of Arendt's to her present tense makes it hard at times to sort out how exactly to apply her thoughts to ours. We are in one historical moment; Arendt moved, in her long career, through several, and responded as her mood and the world's changed. Young-Bruehl demonstrates that Arendt was an amazingly prescient identifier of future problems: the plight of people without state protection; the difficult necessity of forgiveness in politics, manifested in South Africa by the Truth and Reconciliation Commission; the thoughtless drift of American civic life; the challenges Europe might face in moving toward a federation, which she nevertheless endorsed. Young-Bruehl wants us to learn from both Arendt's shrewd suspicions and her serene embrace of the world all at once.

At times, though, the flow of Young-Bruehl's text is so smoothed-out you could almost forget you're reading about the spikily challenging Arendt. And this makes a difference. As Young-Bruehl herself puts it:

Whenever I imagine to myself how Hannah Arendt—who was my teacher—might have judged some phenomenon and brought clarity to it for others, I hear her heavily German-accented voice carefully saying: "Vell, vell, on one hand . . . und den on another hand . . . Und, look here, consider it this way . . ." Then she pauses, and you can actually see in her face how much she is mentally enjoying what Kant referred to as the "enlarged mentality" of opinion sharing, consulting, paying calls on other points of view: "Aber sehen Sie mal! [But look sharp!] Here is the other side, another perspective."

Young-Bruehl's case could use a bit more of this "on the one hand . . . und den on the other." Given the nature of the task she has set herself, she doesn't have time here to tease out some of the odd blind spots, the bugaboos of dated sensibility, that can complicate the reader's experience of Arendt's work. By the same token, Young-Bruehl sometimes misses the chance to get across the sui generis fierceness of Arendt's voice. "Long before the horrible and the ridiculous had merged into the humanly incomprehensible mixture that
is the hallmark of our century, the ridiculous had lost its power to kill," Arendt wrote in The Origins of Totalitarianism. The mocking, hands-held-up-in-the-air irony of "ridiculous" is an important element in Arendt's power to disturb readers into thinking.

This is a useful, admirably fluent guide to Arendt's thought, and Young-Bruehl's concern about current world trends is more than justified. But it may be a testament to the lasting influence of the concepts Arendt left as her legacy that what the book has to say about today's marquee current event is not very surprising. Speaking speculatively on Arendt's behalf, Young-Bruehl puts forward a somewhat standard case against the Bush administration's actions in response to the events of September 11:

It seems to me that Hannah Arendt, had she been alive in 2001, would have gone straight to her writing table to protest that the World Trade Center was not Pearl Harbor and that "war on terror" was a meaningless phrase. Terror is not enemy, it is a method, a means. I can imagine her bringing to bear an argument that she made in both On Revolution and On Violence: to the right and to the left of the political spectrum, among people who have dedicated their lives to preventing revolution and among those who have put their hopes in it, violence has become so habitual and easily rationalized that politicians, revolutionaries, and now terrorists no longer even wonder whether the violence they want to undertake might do more harm than good, especially in cases where there is no identified, or even identifiable, enemy. Violence is what it takes to "make history."

One can nod in agreement with the basic points in this passage and still wonder how precise it is to collapse such different kinds of violence and how much the making of this case required Arendt. Many skeptics have made similar claims since September 11. Arendt did not like to engage in polemics, but she had a formidability about her that transformed debates. It might be useful, for instance, to bring her to bear even more directly on intellectuals who've lent their support to the Iraq war. Here it's interesting to revisit a speech Arendt delivered ca. 1948, at New York's Rand School, to an audience of anti-Stalinist intellectuals. She urged them not to resort to historical clichés in their understanding of the present: "Since they have no contact with and little lively interest in politics as the realm of the statesman, they have degenerated into armchair strategists who marshal the forces of the world for and against Stalin." Sound familiar?

And yet the challenges of understanding history while it's unfolding extend to all of us, not just indulgers in the least helpful clichés. There remains an element of confounding dilemma in Arendt's thought and in our current circumstances that could be more present in this book, which chooses instead to end on her late thoughts about politics and love. We don't lack for scholarly and policy experts who illuminate within their specialist ranges. We have polemical thinkers who do battle and aim to persuade. We have spectator-explainers, who report on what the specialists and the polemicists are up to. And we have contrarians, who tend to make the loudest claims for their own independence but whose thinking is often predirected by the priority they place on staking out unclaimed ground. We have plenty of controversial thinkers. But we have very few with the fortitude to stand in the eye of the conceptual storm, in the way that Arendt did, and report its path.

Sarah Kerr is a writer based in Washington, DC.