The First Amendment to the Constitution of the United States declares that "Congress shall make no law ... abridging the freedom of speech." What does and should this mean? Justice Oliver Wendell Holmes, in his famous Abrams v. United States (1919) dissenting opinion, began what may be the single most poetic paragraph ever written by a Supreme Court justice on the meaning of freedom of speech. Here is that improbable opening line: "Persecution for the expression of opinions seems to me perfectly logical." What could Holmes have been thinking?

Perhaps Holmes was expressing the view that all of us, individually and collectively, have within us a kind of censorship-impulse. Governments are especially prone to censor. As Holmes went on to put it: "If you have no doubt of your premises or your power and want a certain result with all your heart you naturally express your wishes in law and sweep away all opposition." Censorship is thus a kind of social instinct. As caring and responsible citizens of society, especially good and decent citizens of a good and decent society, we are likely to want many results with all our hearts. We want security, we want freedom from fear, we want order, civility, racial and religious tolerance, we want the well-being of our children. We want these things with all our hearts, and when others express opinions that seem to threaten these aspirations, who can blame us for being tempted to express our wishes in law and sweep away the opposition? It is perfectly logical. And that is what, at bottom, freedom of speech is all about.

Over the course of roughly the last 50 years the U.S. Supreme Court has set our nation on a remarkable experiment, often construing the First Amendment in a manner that strenuously defies the natural and logical impulse to censor. In scores of decisions, the Supreme Court has interpreted the First Amendment in a manner that to most of the world seems positively radical. Those decisions are numerous and cover a vast and various terrain, but consider some highlights. Americans have the right to:

• Desecrate the national flag as a symbol of protest.
• Burn the cross as an expression of racial bigotry and hatred.
• Espouse the violent overthrow of the government as long as it is mere abstract advocacy and not an immediate incitement to violence.
• Traffic in sexually explicit erotica as long as it does not meet a rigorous definition of "hard core" obscenity.
• Defame public officials and public figures with falsehoods provided they are not published with knowledge of their falsity or reckless disregard for the truth.
• Disseminate information invading personal privacy if the revelation is deemed "newsworthy."
• Engage in countless other forms of expression that would be outlawed in many nations but are regarded as constitutionally protected here.

Such First Amendment decisions reject the impulse to censor; they are therefore striking as legal doctrines. Perhaps more striking, however, is that these decisions have gained widespread currency within American culture as a whole. The Supreme Court is not alone in its commitment to the free-speech project. While undoubtedly any one decision will often be controversial with the public, which may be deeply divided on topics such as flag-burning or sex on the Internet, on balance what is extraordinary about the evolution of freedom of speech in America over the last 50 years is that it has taken such a strong hold on the American consciousness, a hold that seems to cut across party labels such as "Democrat" or "Republican" or ideological labels such as "liberal" or "conservative." On the Supreme Court itself, for example, justices with hardy conservative credentials such as Antonin Scalia or Clarence Thomas have often been as committed to expansive protection for freedom of speech as justices famous for their liberal views, such as William Brennan or Thurgood Marshall. Appointees of Republican presidents, such as Anthony Kennedy or David Souter, have been as stalwart as appointees of Democratic presidents, such as Stephen Breyer or Ruth Bader Ginsburg, in their articulation of strong free-speech doctrines. So too, in the political arena, views on free-speech issues often do not track along traditional party lines or classic ideological divisions.

This is not to say that in some simplistic sense everybody in America believes in freedom of speech, and certainly it is not to say that everybody in America believes that freedom of speech means the same thing. But it is to say that in a sense both deep and wide, "freedom of speech" is a value that has become powerfully internalized by the American polity. Freedom of speech is a core American belief, almost a kind of secular religious tenet, an article of constitutional faith.

How do we account for the modern American reverence for freedom of speech? Why is this value so solidly entrenched in our constitutional law, and why is it so widely embraced by the general public? Over the years many philosophers, historians, legal scholars and judges have offered theoretical justifications for strong protection of freedom of speech, and in these justifications we may also find explanatory clues.

An obvious starting point is the direct link between freedom of speech and vibrant democracy. Free speech is an indispensable tool of self-governance in a democratic society. Concurring in Whitney v. California (1927), Justice Louis Brandeis wrote that "freedom to think as you will and to speak as you think are means indispensable to the discovery and spread of political truth."

On a communal level, free speech facilitates majority rule. It is through talking that we encourage consensus, that we form a collective will. Whether the answers we reach are wise or foolish, free speech helps us ensure that the answers usually conform to what most people think. Americans who are optimists (and optimism is a quintessentially American characteristic) additionally believe that, over the long run, free speech actually improves our political decision-making. Just as Americans generally believe in free markets in economic matters, they generally believe in free markets when it comes to ideas, and this includes politics. In the long run the best test of intelligent political policy is its power to gain acceptance at the ballot box.

On an individual level, speech is a means of participation, the vehicle through which individuals debate the issues of the day, cast their votes, and actively join in the processes of decision-making that shape the polity. Free speech serves the individual’s right to join the political fray, to stand up and be counted, to be an active player in the democracy, not a passive spectator.

Freedom of speech is also an essential contributor to the American belief in government confined by a system of checks and balances, operating as a restraint on tyranny, corruption and ineptitude. For much of the world’s history, governments, following the impulse described by Justice Holmes, have presumed to play the role of benevolent but firm censor, on the theory that the wise governance of men proceeds from the wise governance of their opinions. But the United States was founded on the more cantankerous revolutionary principles of John Locke, who taught that under the social compact sovereignty always rests with the people, who never surrender their natural right to protest, or even revolt, when the state exceeds the limits of legitimate authority. Speech is thus a means of "people-power," through which the people may ferret out corruption and discourage tyrannical excesses.

Counter-intuitively, influential American voices have also often argued that robust protection of freedom of speech, including speech advocating crime and revolution, actually works to make the country more stable, increasing rather than decreasing our ability to maintain law and order. Again the words of Justice Brandeis in Whitney v. California are especially resonant, with his admonition that the framers of the Constitution "knew that order cannot be secured merely through fear of punishment for its infraction; that it is hazardous to discourage thought, hope and imagination; that fear breeds repression; that repression breeds hate; that hate menaces stable government; that the path of safety lies in the opportunity to discuss freely supposed grievances and proposed remedies; and that the fitting remedy for evil counsels is good ones." If a society as wide-open and pluralistic as America is not to explode from festering tensions and conflicts, there must be valves through which citizens with discontent may blow off steam. In America we have come to accept the wisdom that openness fosters resiliency, that peaceful protest displaces more violence than it triggers, and that free debate dissipates more hate than it stirs.

The link between speech and democracy certainly provides some explanation for the American veneration of free speech, but not an entirely satisfying or complete one. For there are many flourishing democracies in the world, but few of them have adopted either the constitutional law or the cultural traditions that support free speech as expansively as America does. Moreover, much of the vast protection we provide to expression in America seems to bear no obvious connection to politics or the democratic process at all. Additional explanation is required.

Probably the most celebrated attempt at explanation is the "marketplace of ideas" metaphor, a notion that is most famously associated with Holmes' great dissent in Abrams, in which he argued that "the best test of truth is the power of the thought to get itself accepted in the competition of the market." The marketplace of ideas metaphor does not posit that truth will emerge from the free trade in ideas, at least not instantly. That would be asking too much. It merely posits that free trade in ideas is the best test of truth, in much the same way that those who believe in laissez-faire economic theory argue that over the long haul free economic markets are superior to command-and-control economies. The American love of the marketplace of ideas metaphor stems in no small part from our irrepressible national optimism, the American "constitutional faith" that, given long enough, good will conquer evil. As long as this optimism is not blind naiveté, but is rather a motive force that encourages us to keep the faith in the long view of history, it can be a self-fulfilling prophecy. Just as we often have nothing to fear but fear, hope is often our best hope. Humanity may be fallible, and truth illusive, but the hope of humanity lies in its faith in progress. The marketplace metaphor reminds us to take the long view. Americans like to believe, and largely do believe, that truth has a stubborn and incorrigible persistence. Cut down again and again, truth will still not be extinguished. Truth will out, it will be rediscovered and rejuvenated. It will prevail.

The connection of freedom of speech to self-governance and the appeal of the marketplace of ideas metaphor still, however, do not tell it all. Freedom of speech is linked not merely to such grandiose ends as the service of the democracy or the search for truth. Freedom of speech has value on a more personal and individual level. Freedom of speech is part of the human personality itself, a value intimately intertwined with human autonomy and dignity. In the words of Justice Thurgood Marshall in the 1974 case Procunier v. Martinez, "The First Amendment serves not only the needs of the polity but also those of the human spirit — a spirit that demands self-expression."

Many Americans embrace freedom of speech for the same reasons they embrace other aspects of individualism. Freedom of speech is the right to defiantly, robustly and irreverently speak one’s mind just because it is one’s mind. Freedom of speech is thus bonded in special and unique ways to the human capacity to think, imagine and create. Conscience and consciousness are the sacred precincts of mind and soul. Freedom of speech is intimately linked to freedom of thought, to that central capacity to reason and wonder, hope and believe, that largely defines our humanity.

If these various elements of our culture do in combination provide some insight into why freedom of speech exerts such a dominating presence on the American legal and cultural landscape, they do not by any means come close to explaining the intense and seemingly never-ending legal and cultural debates over the limits on freedom of speech.

There are limits. The major labor of modern First Amendment law is to articulate the points at which those limits are reached. This ongoing process is often contentious and difficult, and no one simple legal formula or philosophical principle has yet been discovered that is up to the trick of making the job easy. Americans thus continue to debate in political forums and litigate in legal forums such issues as the power of society to censor offensive speech to protect children, the power to arrest speakers spreading violent or hateful propaganda for fear that it will foment crime or terrorism, the permissibility of banning speech that defeats protection of intellectual property, the propriety of curbing speech to shelter personal reputation and privacy, the right to restrict political contributions and expenditures to reduce the influence of money on the political process, and countless other free-speech conflicts.

Yet while the country continues to struggle mightily to define the limits and continues to debate vigorously the details, there is surprisingly little struggle and debate over the core of the faith. Americans truly do embrace the central belief that freedom of thought, conscience and expression are numinous values, linked to our defining characteristics as human beings. While limits must exist, American culture and law approach such limits with abiding caution and skepticism, embracing freedom of speech as a value of transcendent constitutional importance.