When Representative John Lewis said recently that "Barack Obama is what comes at the end of that bridge in Selma," he was conveying an important truth: America is a protest nation. From the Declaration of Independence to the historic 2008 presidential election, our politics and culture have been profoundly changed by small acts of protest and mass mobilizations. Such dissent has come in a wide variety of forms—conservative and progressive, sweeping and incremental, violent and peaceful, individual and collective. Often, American radicalism has drawn its inspiration from the nation’s revolutionary founding claims of liberty, equality and the rights of citizenship.

Still, to refer to someone as radical is to risk offense. Though the word can reasonably be defined as "going to the root of things," it is more commonly interpreted as "drastic" or "extreme." Radicals are those who decry the status quo, demand fundamental change. These kinds of people almost always make others nervous—especially those in power. Without them, however, real change is much harder to achieve.

The past generation or so has been a fascinating period for historians of American radicalism. Reckless Reaganomics paved the way for a disappointing decade of Clintonian compromise, flanked as it was by two Bush presidencies, the second much more awful than the first. Even in our most cynical imaginations, we could not have predicted that the terrorist attacks of 9/11 would be followed by two botched wars (one justified by lies), Guantánamo Bay, legalized torture, Hurricane Katrina and the worst economic crisis since the Great Depression.

And yet somehow the tragedies of the Bush era failed to produce a countervailing progressive social movement of the type that roiled America in the 1960s. The most conspicuous expression of radicalism right now, the Tea Party movement, comes not from the left but from the far right. Inspired by the noisy rhetoric of media elites like Rush Limbaugh and his allies at Fox News, its rank and file embody a peculiar blend of nationalism and antigovernment conspiracy theories, evangelical fervor and xenophobic bigotry. They see an America that is changing rapidly—one where straight white men must learn to share power and social status with women, minorities and gays, and where the Oval Office is occupied by a man who is not only African-American but also cosmopolitan, intellectual, stylish and sophisticated. Frightened by these new realities, they carry signs that say, We Want Our Country Back.

But the rest of us deserve to have our history back. Though some of these right-wing populists claim to be working in the tradition of Thomas Paine, they would be hard-pressed to identify any specific commonalities between themselves and the eighteenth-century deist, who is far more accurately embraced as a forerunner of left-wing radicals. Others have sought to link President Obama to socialism, communism, Nazism, Fascism and the Vietnam-era antiwar movement. Even the most general student of history should be able to recognize how muddle-headed these designations are when directed simultaneously at a single person.

In the face of all this, it is certainly easy to be pessimistic about the role that progressive radicalism might play in modern America. Look more carefully, though, and one can find evidence of a widening recognition and acceptance of the place of such radicalism. In this respect, the 2008 election—so full of historic firsts—may have been a turning point, a profound cultural shift as well as a generational passing of the torch. Throughout the long campaign, Obama’s opponents tried to portray him as different, foreign or unacceptable in a host of ways. And while this smear campaign took on a predictable racial gloss, it was also an attempt to make him appear too radical by calling attention to his tenuous associations with an "angry" black minister, an "anti-American" education professor and "foreign-born" Muslims. Even his impressive and likable wife was called unpatriotic. That Obama’s candidacy survived these attacks says a great deal about his political skill, but it may also exemplify shifting perceptions of radicalism in our culture—our evolving ability to discern real threats from imagined ones.

The two of us have just published an anthology, Protest Nation, in which we present famous speeches, essays and manifestos by Upton Sinclair, Eugene Debs, Betty Friedan, Martin Luther King Jr., Rachel Carson, Noam Chomsky, Angela Davis, Harvey Milk and many others in order to illuminate the important role radicals have played in American history. It is our hope that the book will function as a field manual of sorts for progressive activists.

Surrounded by tea baggers and terrorists, we also wanted to bring about a more charitable perception of radicalism by listing some of the things progressive activists have achieved. They include: the American Revolution, the abolition of slavery, universal suffrage, public education, public parks, wildlife reserves, integration, coeducation, the eight-hour workday, collective bargaining, health and safety standards, child- and prison labor laws, reproductive choice, same-sex partner benefits, public health clinics and multicultural studies. It’s an impressive (albeit incomplete) list, and it underscores the fact that America would be a far less decent and less democratic place if not for the work of activists who have struggled to make real the country’s founding promises of freedom and equality.

As we begin the next American century, it is worth remembering how many of the things we take for granted have radical roots. It is also important to observe that radical thinking and action can be valuable regardless of their degree of influence. In times of great crisis and repression, citizens may find it worthwhile simply to speak their minds, demand their rights and dream of a better world. As Margaret Mead exhorted us: "Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has."

Democracy is not inevitable. It cannot be imposed from on high or from afar; it must be generated from below. In these precarious times, we need to remember that liberty and equality have never been given freely or distributed equally—in the United States or anywhere else.