Sens. Bernie Sanders and Elizabeth Warren, leaders of the ascendant left wing of the Democratic Party, believe that socialism in some form is crucial for America's better future. Young people seem to be buying the message. According to a May 2016 Gallup poll, 55 percent of Americans under the age of 30 have a positive view of socialism.

So, this Labor Day, as leftists invite you to step along their pathway to a workers' utopia, let us consider what capitalism has already achieved for this country, and especially for its wage earners.

First, the economy has created social mobility on a level the world has known in no other time and in no other place. Not every member of the public will become wealthy or even enter the middle class, but doing so is a realistic aspiration for anyone. As the chart below indicates, 59.9 percent of this country's citizens are in the middle class.

That's just the start. Ordinary people in this country enjoy a standard of living that the wealthy of yesteryear, even kings and aristocrats, could not have dreamed of. This is largely thanks to the innovation of other Americans.

Instant communications and endless entertainment are at every worker's fingertips. Drugs exist to treat and cure ailments (both those that are deadly and those that are merely difficult and unpleasant) that were once incurable. Jet engines can move you at an affordable price from New York to Los Angeles or from Miami to Anchorage in a matter of hours. Computer software instantly handles problems today that took hours of toil in the past. America's innovators shape humanity's future.

Whether you want to measure American achievement by counting the Nobel Prize winners there are among our scientists and inventors — at 353, we're way ahead of anyone else — or by the tough effectiveness of our soldiers, it is dazzlingly clear that American know-how leads the world. Whether you want to measure it in the high rate of homeownership, the widespread access to endless entertainment and affordable vacations, the robust community spirit, or the relative freedom from government interference, the average American's ability to pursue happiness is unparalleled.

This is no accident but the legacy of a political system that is flexible enough to change and right historic wrongs, yet rigid and scrupulous in its respect for freedom. The American way has achieved a more comfortable and dignified life for workers than any other.

Let us look at the socialist alternative favored by Sanders and Warren. The miseries, deprivations, and backwardness it has inflicted on populations wherever and whenever it has been tried are boundless. They amount to the biggest empirical data set of political and economic failure in the history of humankind. In Venezuela, to take only the latest unfortunate experiment, it has meant the world's largest oil reserves being wasted and stolen while children starve on the streets. The historical legacy of Soviet socialism, National Socialism, and Maoist Communism, to cite the most egregious versions of this poisonous left-wing political ideology, is so well known that it does not need to be rehearsed here.

Even those countries that experienced the more gentle "democratic socialism," such as modern South Africa and Brazil, socialism has allowed corrupt politicians to pilfer state industries while the poor live and die young in slums. Even in the socialized utopias of Europe, it has meant destructive youth unemployment rates, a dearth of innovation, and death panels in hospitals.

To the extent that these nations have succeeded, it is mostly because they have come to imitate us. It is in spite of, not because of, their sympathy for ideas that turned Cuba and North Korea into the world's two largest prisons.

America is not perfect. Its health care system is absurdly expensive (although also the world's most effective). Its extortionate higher education system increasingly resembles a fraudulent pyramid scheme. Its ballooning entitlement state robs the young and gives to the old, with such generosity that today's Medicare recipients receive three times more in benefits than what they paid in. And far too many Americans are victims of crime, gangs, and collapsing families.

But every society has problems, and ours could be so much worse. Just look at those run under the system that leading lights of the Democratic Party regard as an ideal.