The "Left" does not simply consist of people who are more extreme than garden variety liberals and progressives; it consists of several quite different groups. And many are quite overtly distant or even disdainful of liberals and "liberalism", although most embrace "progressivism" even if there is little consensus about what that is.

The most familiar are various socialists and communists, who argue that social institutions -- often the government -- should distribute obligations and resources rationally and equitably. Major leftists of this category include Karl Marx and Jean Jaurès. While socialists and communists in the Twentieth Century influenced liberal and progressive (social democratic) politicians, they also provided bonapartists like Joseph Stalin and Mao Zedong with rationales for their regimes.

On the other hand, anarchists argue that such institutions (particularly the government) are themselves the primary source of human misery; major anarchists include Pierre-Joseph Proudhon and Mikhail Bakunin.

There is also a "Romantic Left", which traces its ancestry through figures like Jean-Jacques Rousseau, Henry Thoreau, and Leo Tolstoy, and much of the modern environmental movement from Rachel Carson on.

The Romantic Left has has influenced innovators who developed machinery for influencing western liberal democracies, such as Saul Alinsky, Mohandas Gandhi, and Martin L. King, Jr..

While radicals and revolutionaries are as ancient as John the Baptist and Wat Tyler, it was Mr. Gutenberg that made mass radical dissent more than, say, chronic complaining and occasional explosions.

Major media organs tend to be concerned with being responsible members of society, or responsibly providing a reasonable return to their investors, and tend to be wary of the Left. That leaves the field to a vast and diverse array of newspapers, magazines, websites, and other organs collectively if misleadingly called the Left Wing Press.

• AlterNet is a news service.
• Counterpunch is co-edited by one of the Left's most notorious curmudgeons.
• The Daily Kos is a sort of blog-world for American progressives.
• Democracy Now is a radio system with a growing web presence.
• In These Times was founded to "identify and clarify the struggles against corporate power now multiplying in American society."
• Mother Jones is the American Left's glitziest outlet.
• The Nation is the American Left's leading daily.
• The Guardian called the British-based New Left Review the "flagship of the Western intellectual Left."
• A British socialist magazine founded by members of the Fabian Society, the New Statesman is one of the great survivors.
• Pacifica is a small radio network.
• The Progressive is one of the American Left's honest gloomy Puritans.
• The Real News Network covers "the critical issues of our times."
• The Utne Reader trolls through the Left, presenting to its readers the bright, glittery loot it finds.

There are also many weekly tabloids making up an Alternative Press of independent media outlets (along with small radio stations and other groups).

• It is almost a contradiction in terms, but there are alternative newspaper chains, including the Phoenix and Creative Loafing, which has a tabloid in Tampa. Such chains sometimes focus on being entertainment tabs, with a little left-wing politics on the side.
• For more entertainment + left wing politics see the Aquarian, the Austin Chronicle, the Buffalo Beast, the Chicago Reader, the L. A. Weekly, the Metro Times, the Miami New Times, the Philadelphia City Paper, the Sacramento News & Review, the San Francisco Bay Guardian, the San Francisco Weekly, the Shepherd Express, and the Stranger.

• New areas of study -- including specialties devoted to particular groups (like Women's Studies) -- appeared, but perhaps the biggest impact has been the development of more systematic views of how power affects perception, one of the major issues in Critical Theory and Culture Studies. But the old Frankfurt School -- now the Institute for Social Research at the J. W. Goethe University in Frankfurt -- is not what it was, and it is not clear what impact this endeavor has.
• Part of the legacy of the Cold War -- fought between American and Russia, so the quip goes, and won by Germany and Japan -- was "peace studies" as an academic field of study. Institutions devoted to peace research and conflict resolution include the United Nations University, and the International Peace Research Association maintains an online Directory of academic organizations devoted to peace research, like the Albert Einstein Institute.
• And there are organizations with broader mandates, such as the Institute for Policy Studies, which arose from the Vietnam era.

• Greenpeace, the People for the Ethical Treatment of Animals and the Sea Shepherds speak for other organisms and ecosystems.
• The National Gay Bisexual Lesbian Transgender Task Force defends the rights of people with a variety of sexual orientations.

And then there are the more direct descendents of the German & British movement associated with Karl Marx and Friedrich Engels.

• The Old Left ranged from those who had never liked the communists to those who were disillusioned. (By the time Nikita Khrushchev condemned Stalin (but not mentioning his own misconduct) in 1956, most Leftists were familiar with Leon Trotsky's similar venture of kettle-calling-pot-black, and much of the Old Left was toying with ideas like communism is a form state capitalism, or a form of hero worship, or even a rationale for a new exploitative class of bureaucrats.) Some Old Leftists are still around, along with some New Leftists.
  • The Green Party of the United States was very influential a decade or so ago, but its future is uncertain. The Democratic Socialists of America is fairly ineffectual.
  • And some are (reformed and perhaps a little lite) Trotskyite, like the Committee for a Workers' International, the Fourth International, the International Marxist Tendency, and Solidarity (not to be confused with the Polish Solidarnosc labor union organization) (but with a special relationship with the International Socialist Organization.
• And of course, there were the Communists. No list of Left wing groups would be complete without the Communist Party USA: "Radical Ideas. Real Politics." Alas, the Daily Worker is no more, but there is a successor, the People's World, and the British Morning Star is still around.

Liberals believe that people are and should be rational and good, and that government should be rational and rely on the goodness of people in working for the public interest. Progressives believe that government and society should actively promote the public welfare. These two goals are not particularly compatible, hence frequent food fights.

Modern liberalism goes back to Age of Reason and Enlightenment philosophers like Benedict Spinoza, John Locke, Baron de Montesquieu and Immanuel Kant, and more recently John Stuart Mill and John Dewey. Perhaps the gratest accomplishment of liberalism -- yes, of liberalism -- is liberal democracy (sometimes called western democracy). Major liberal politicians include Thomas Jefferson. William Gladstone, and Earl Warren.

Since liberty and justice were in the public interest, many liberals came to believe that government should advance liberty and justice: in America, the progressives (like Theodore Roosevelt), and in Europe the social democrats (like Eduard Bernstein) pushed for socialist reforms -- essentially industrial and commercial regulation and support for public infrastructure and welfare -- within the framework of liberal democracy. Major progressives include Franklin Roosevelt, Lyndon Johnson, and Robert F. Kennedy. The traditional tension in liberalism -- which progressives try to answer -- is the conflict between liberty and justice.

• The Daily Beast recently purchased Time magazine's old Democratic foil, Newsweek magazine -- which is prone to emulate Time at times.
• The U. K. Guardian is probably the world's pre-eminent liberal newspaper.
• MSNBC is the most prominent progressive outlet in America.
• Salon is a creature of the new San Francisco bay area.
• The Village Voice could be regarded as America's pre-eminent progressive alternative newspaper.

• The two liberal-to-center metropolitan newspapers I am most familiar with are the Sacramento Bee, serving northern California, and the Tampa Bay Times, serving west central Florida.

• The Atlantic published those Nineteenth century writers you studied in school.
• The Atlantic may have published Emerson's essays, but Harper's ran Nast's cartoons.
• The New Yorker is the great American phoenix that every American writer aspires to publish in -- if only as an item in The Mail.

• The American Prospect has become more than just a reaction to the Reagan revolution.
• Commonweal is a catholic Catholic publication.
• Not as popular as it once was, Ms. is a special interest publication that makes 50 % of the population its special interest, albeit with a leftish tilt.
• As the voice of responsible liberalism, the New Republic embodies the Washington limousine liberal beltway that the Left and Right can't abide.
• Tilting at windmills, the Washington Monthly remains faithful to the mainstream that runs from FDR to LBJ.

• The Huffington Post is a sort of uber-blog for progressives and liberals.
• Literature and Economics may swing between Left and Right as fashion dictates, but the Nobel Peace Prize committee maintains one of the most powerful wurlitzers in progressive politics.

The Enlightenment was more liberal than progressive, but it provided wind for both sets of sails. But liberals and progressives agreed that human beings were fundamentally good, and that the social systems that governed them could and should be rational as well as just. One of the primary notions was that of the Social Contract, the idea that government is the result of a contract held in common by the people, either literally or metaphorically, and this has formed the basis for liberal prescriptions from John Locke to Baron Montesquieu (both of whom inspired our Founding Fathers), to John Rawls. This alleged goodness and rationality is the core of the basic disagreement between liberals and progressives versus conservatives.

It is a particularly liberal belief that if a think tank provides factual support for a policy, that policy will be implemented. But liberal think tanks tend to lack the resources to compete effectively with their competitors across the aisle.

• The Alan Guttmacher Institute is a single issue (birth control, including abortion) institute. The Center for American Progress develops "progressive ideas for a strong, just, and free America," and has a super-blog Think Progress and a student outreach Campus Progress. The Center for Progressive Reform consists of university professors conducting studies on consumer issues, the environment, workplace conditions, etc. The Center on Budget and Policy Priorities focuses on the federal budget. Citizens for Tax Justice pushes tax reform. The Economic Policy Institute focuses on low- and middle-income Americans. The Pacific Institute is largely concerned with environment and sustainability. The Progressive Policy Institute is a creation of the essentially centrist Democratic Leadership Council; and is "a place for pragmatic progressives." The Urban Institute engages in "nonpartisan economic and social policy research". The World Policy Institute is one of the old (post-WW2) internationalist organizations. The World Resources Institute is an environmentalist think tank.

• The American Labor Studies Center, the Harry Bridges Center for Labor Studies, the Higgins Labor Studies Program, the Indiana University Labor Studies Program, the (German) Institute for the Study of Labor (IZA), the Pennsylvania State Labor Studies & Employment program, and the UCLA Labor Center.

• The National Baptist Convention has a plurality of African Americans among its members.
• The Religious Society of Friends (the Quakers).
• The United Church of Christ.
• And of course, the Unitarian Universalist church, which as it name makes clear, holds that there is exactly one God -- revered by all religions.

• The American Federation of Labor / Congress of Industrial Organizations is the somewhat centrist umbrella that includes affiliated unions like the American Federation of Teachers.
• The three great independents are the National Education Association, the Service Employees International Union, and the United Autoworkers Union, although the United Farmworkers Union is the sentimental favorite.

Political action is the perennial dream, and effective action requires political organization.

• There are political parties. The Democratic Party is actually centrist, but it pretends to be leftish in its fundraising literature.
• Being in a party requires either compromise or delusion, and uncompromising realists prefer to form pressure groups. Norman Lear's People for the American Way was and is largely a reaction to the Right. Common Cause claims to hold power accountable; they maintain a somewhat entertaining Right Wing Watch of people and organizations who would not be so amusing if they actually got real power.
• Lawyers have long formed activist groups to advance their causes by legal education and litigation. Liberal and progressive legal groups include the Brennan Center for Justice (named after the late U. S. Supreme Court Associate Justice William Brennan). George Soros's Open Society Foundations supports efforts to spread democracy and advance progressive goals throughout the world.
• Some political organizations have narrower agendas. The American Civil Liberties Union defends our constitutional rights, and celebrates Christmas with its annual suit to ban creches from government property (these suits being a particularly American tradition). The Center for Science in the Public Interest is a consumer advocacy organization. The National Association for the Advancement of Colored People and the National Urban League are the pre-eminent civil rights organizations. The National Organization for Women is the nation's pre-eminent feminist organization. United for a Fair Economy focuses on the inequitable distribution of wealth. The Council on American–Islamic Relations and the Anti-Defamation League (of B'nai B'rith) defend Muslims and Jews in America -- when they aren't hurling brickbats at each others' constituencies. The Brady Campaign to Prevent Gun Violence advocates regulation of guns. The National Taxpayer's Union is one of those petit bourgeois, classically liberal, anti-progressive organizations that gets the Left foaming at the mouth; the Tax Justice Network pushes for transparent and equitable taxation.
• So many things depend on the environment, from our spiritual health to our food supply, that a number of organizations are devoted to it. This includes Mikhail Gorbachev's Green Cross International, arising in part from a need for a "international Green Cross that offers its assistance to States in ecological trouble." Also, nature organizations like the Audubon Society, the Sierra Club, and the World Wildlife Fund.
• Abortion is one of the most divisive issues in America, and on the Left as well (in fact, the assertion that it is divisive on the Left is controversial). So abortion gets a remarkable -- some might even say inordinate -- amount of attention. Emily's List and the organization that recently called itself the National Abortion and Reproductive Rights Action League (NARAL) are pro-choice while Feminists for Life is pro-life. (Of course, the most effective way to bring abortion rates down would be to make contraception free and widely available ... this is no secret, and that's enough to show how much the abortion debate is actually about abortion ...)

Aristotle argued for moderate government by men of moderate means acting moderately in their public and private lives. Since then, stirred by (the liberal) Gary Trudeau's rallying cry, "The World Needs Grown-ups," centrists have advocated grown up virtues.

But moderation is a controversial subject: Tom Paine claimed that moderation in principle is always a vice, while Barry Goldwater claimed that moderation in the pursuit of justice is no virtue. Moderates argued that they were the advocates of sanity and common sense.

During the Eighteenth century, the notion of a balance of power (originally in foreign affairs) emerged at the same time modern political parties (such as the Whigs and the Tories of Great Britain). The moderate George Washington made the typical argument in his Farewell Address that a faction (party) will try "... to make the public administration the mirror of the ill-concerted and incongruous projects ... rather than the organ of consistent and wholesome plans digested by common counsels, and modified by mutual interests."

Since then, extreme partisanship has just as often led to paralysis -- perhaps the most notorious example being the Weimer Regime (whose collapse led to the ascendancy of the Nazi Party). But moderation -- now called bipartisanship -- remains controversial.

The centrists in the media are often centrists because they value moderation itself as a virtue, often regarding moderation as an attribute of maturity (one of the stereotypes of adolescence is extremism). Others may position themselves in the center strategically, although the center may not be the best place to be (Leftist commentator Jim Hightower has quipped that where he comes from -- Texas -- the only things in the middle of the road are yellow lines and dead armadillos). Even others are "centrist" because if you viewed the their positions (often extreme) on a large number of issues, the average would be close to center (these may be what Pogo cartoonist Walt Kelly called the extreme middle). However vanilla it may appear to be, the Center is no more monochromatic than anyplace else on the political spectrum.

The Left calls them the Corporate Media while the Right calls them the Mainstream Media. Criticized by both sides, they tend to regard themselves as the responsible center, but media watchdogs may be correct in pegging them leftish on social issues and private morality, and rightish on economic and public policy, and not particularly moderate in either. The main actors are:

• Mismanaged, unreliable in science issues, and prone to pander to the defense establishment, The New York Times calls itself "The Newspaper of Record," although everyone else calls it the Old Gray Lady.
• The Times' pre-eminent competitor is probably The Washington Post, which is sort of a small-town newspaper whose small town is the capitol. Of course, the Los Angeles Times would object to following the Post.
• It may not have the highest ratings, but whenever there's an emergency, people turn to the Cable News Network.

• Not venerable at all, USA Today aims to please, and is available in hotels across the country.
• The Associated Press and Reuters have a compelling business reason to be more moderate: they make their money by selling stories to other outlets, which they don't want to antagonize.
• The great news popularity contest is Google News; Google has software robots called "spiders" that select news based on various measurable popularity metrics. Yes, Google does have competitors, notably Yahoo News, which may be the most visited news site on the web. Such sites will tell you what everybody else is reading.
• And then there are new outlets like Slate that package commentary as news.

In many civilizations, there are a few thoughtful people who support moderation, either as an ideal in itself, or at least as a necessary ingredient for good governance and sane living. The resulting philosophy is often more grown up, and therefore usually less entertaining. However, from its central vantage point, one can see things from the Center that one might miss elsewhere. Take a long look at this picture, and remember that (the somewhat liberal) John Tenniel drew it for (the somewhat conservative) Lewis Carroll's Looking Glass ...

Think tanks need resources to support scholars, and a think tank that desires a broad and stable base will tend to be sort of centrist. The bigger respectable think tanks tend to be centrist, while the bigger disreputable ones -- which rely on a few sugar daddies -- tend to be more right wing.

• The story is that the Aspen Institute was inspired by Mortimer Adler's Great Books and Great Ideas movements.
• In 2007, some senior politicians -- largely veterans of Congress -- from both parties founded the Bipartisan Policy Center.
• The Brookings Institution is your father's Oldsmobile. Brookings and the progressive Urban Institute sponsor the Tax Policy Center.
• Andrew Carnegie charged his Carnegie Endowment for International Peace to "hasten the abolition of war, the foulest blot upon our civilization."
• The Council on Foreign Relations publishes Foreign Affairs.
• The Kaiser Family Foundation concentrates on health issues.
• The New America Foundation is the biggest new boy on the block.
• The Peterson Institute for International Economics is a rather establishmentarian creature.
• The RAND corporation earned a reputation for cold -- some would claim cold-blooded -- objectivity.
• The Woodrow Wilson International Center for Scholars publishes the Wilson Quarterly.

• Ferociously liberal, ferociously anti-progressive, radically anti-conservative, prone to sympathy for the romantic Right, the Reason Foundation seems to exist largely to confound the pigeonholes.
• Small Business Majority conducts studies and makes reports on issues facing small businesses.

The way that the U. S. Constitution is supposed to work is that the branches of the U. S. government are forced to the center by checking and balancing each other. Those branches are the Executive, with the White House on top; the Legislative, divided into an upper house, the Senate, and the lower house, the HOuse of Representatives; and the Judicial, with the Supreme Court. All these bodies float on top of a massive administrative superstructure of executive agencies, regulatory agencies, and courts.

Some centrist organizations are self-consciously centrist, pushing centrist policies.

• The Democratic Leadership Council proposes to rescue the Democratic Party from its disintegrating base by seeking a less progressive and well-heeled clientele willing and able to pay for lots of television.
• A group of grumpy independents launched a bipartisan on-line non-party, Americans Elect, but its failure to select a candidate for the 2012 election makes its future uncertain.
• The International Brotherhood of Teamsters has a ... colorful ... history, and after a long dalliance with shady conservatives, it is more receptive to progressive notions.

• Agencies like the Civil Rights Commission, the Federal Elections Commission, the National Labor Relations Board, and the Securities and Exchange Commission are supposed to be centrist, but they are occasionally not as independent as they ought.
• The Organisation for Economic Co-operation and Development arose out of the Marshall Plan era and continues to push economic development and liberal democracy. The world Bank aims to help the Third World.

• The Sikh Coalition is a volunteer organization seeking to build friendly relations between Sikhs and other Americans.
• The Education Trust supports a number of moderate reforms.

And there are centrist religious organizations. Religion is not beige, and a religious organization is often centrist simply because, on average, it isn't anything else. But such an organization will have many diverse points of view, especially if it is part of an ecumenical, interfaith, or (parental guidance warning here) movement. Such organizations include the Council for a Parliament of the World's Religions and the World Council of Churches.