Democratic presidential candidate Bernie Sanders speaks to his supporters during a rally at the Covelli Centre on March 14 in Youngstown, Ohio. (Ricky Carioti/The Washington Post)

Each week, In Theory takes on a big idea in the news and explores it from a range of perspectives. This week, we’re talking about the rise of socialism.

John Bellamy Foster is editor of Monthly Review, an independent socialist magazine, and co-author with Robert W. McChesney of “The Endless Crisis: How Monopoly-Finance Capital Produces Stagnation and Upheaval from the USA to China.”

National income can be likened to a pie. If between one year and the next the pie gets bigger, everyone can have a bigger slice. But if, instead, the size of the pie stays the same, a bigger slice for some can only mean a smaller slice for others.

This helps us understand the present dismal state of the U.S. economy and the impetus behind Bernie Sanders’s electoral campaign, which is aimed at the needs of workers and working families. For decades, U.S. economic growth has stagnated, with each succeeding decade experiencing a lower rate of growth. Under these circumstances, the rapidly increasing income of those at the top — or what Sanders likes to call the “billionaire class” — is at the expense of the income shares (slices of the pie) of those at the bottom.

The 400 richest billionaires in the country now have more wealth than the bottom half of income earners, representing some 150 million people. The share of wages in national income has been falling while property income has been increasing. Jobs are more precarious. Vast numbers of people have dropped out of the labor force. Although official unemployment has decreased in the past few years, good jobs paying livable wages remain extremely hard to come by. More people are falling into poverty. A majority of students in public schools are now classified as poor or near-poor.

The political establishment, consisting of the duopoly of the Democratic and Republican parties, has been largely oblivious to the deteriorating conditions of the majority of people. Since the poor, including the working poor, are much less likely to vote and have little financial clout, they are easily discounted. Money dominates U.S. politics at every level. The Supreme Court’s 2010 Citizens United decision, which opened the floodgates to unrestricted large donations from the corporate rich, has enormously tarnished the image of American democracy. It is now common to hear that the United States is, to quote the memorable phrase of economists Paul Baran and Paul Sweezy in 1966, “democratic in form and plutocratic in content.”

It is this worsening condition of the U.S. body politic that accounts for the extraordinary phenomenon of Bernie Sanders’s campaign for president. Sanders portrays himself as a democratic socialist in the mold of the most radical phase of the Franklin D. Roosevelt administration, which proposed an Economic Bill of Rights to guaranteed full employment and economic security for all Americans.

In advocating democratic socialism, Sanders has promoted a pragmatic politics of the left. His proposals include a sharp increase in taxes on the billionaire class, free college tuition and single-payer health insurance, guaranteeing health insurance to the entire population regardless of jobs and income. He advocates job programs in the tradition of the New Deal. All of these proposals represent things that have been accomplished in other countries, particularly the Scandinavian social democracies, where the populations are better off according to every social indicator. By portraying them as possible here, Sanders has brought the idea of socialism — even a moderate kind — from the margins into the center of U.S. political culture.

What is most remarkable about the Sanders phenomenon is that despite unrelenting hostility from the media gatekeepers of the status quo — for example, Adam Johnson at FAIR.org documented that The Washington Post ran 16 negative stories about Bernie Sanders within 16 hours on March 8 — he has continued to draw record crowds. He has also obtained more votes from those under age 30 than Clinton and Trump combined, pointing to a weakening of the power of the corporate media over political information in U.S. society and the growing influence of social media, at least amongst youth. As David Auerbach of Slate reported, “Online social networking has allowed Sanders supporters to reinforce one another’s beliefs, so that the general shutout of Sanders by the mainstream media — and even a good deal of the leftist media — has allowed Sanders to survive where he would have suffocated even in 2008.”

If there is any larger lesson here it is the resilience and widespread appeal of socialism with its root egalitarian values. Socialism has always been part of American culture. It would no doubt disturb today’s Republican Party to learn that one of Lincoln’s favorite political writers was Karl Marx, European columnist for Horace Greeley’s paper, the New York Tribune.

In Sanders’s vision of democratic socialism, a society lacking basic equality and fairness for every individual cannot be considered a democratic society in any meaningful sense. Real, live democracy leads in the direction of socialism. For millions of Americans today, what Sanders is expressing in his idea of democratic socialism is nothing less than the American Dream.

Explore these other perspectives:

Christine Emba: Our socialist youth: Why millennials are embracing a bad, old term

Stanley Kurtz: How socialists from the ’60s primed millennials to Feel the Bern

Sean McElwee: Millennials are significantly more progressive than their parents